JP2008071832A - Group iii nitride semiconductor element and method for manufacturing the same - Google Patents

Group iii nitride semiconductor element and method for manufacturing the same Download PDF

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JP2008071832A
JP2008071832A JP2006247232A JP2006247232A JP2008071832A JP 2008071832 A JP2008071832 A JP 2008071832A JP 2006247232 A JP2006247232 A JP 2006247232A JP 2006247232 A JP2006247232 A JP 2006247232A JP 2008071832 A JP2008071832 A JP 2008071832A
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Yoshitaka Taniyasu
芳孝 谷保
Makoto Kakazu
誠 嘉数
Toshiki Makimoto
俊樹 牧本
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Nippon Telegraph and Telephone Corp
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<P>PROBLEM TO BE SOLVED: To provide a structure for obtaining conductivity in the vertical direction without causing the generation of a crack in a vertical type semiconductor element structure using an AlN and high Al composition AlGaN on a conductive SiC substrate. <P>SOLUTION: An Si-doped n-type Al<SB>0.8</SB>Ga<SB>0.15</SB>In<SB>0.05</SB>N (film thickness: 3 nm, Si concentration: 3×10<SP>19</SP>cm<SP>-3</SP>)/Al<SB>0.5</SB>Ga<SB>0.45</SB>In<SB>0.05</SB>N (thickness: 3 nm, Si concentration: 3×10<SP>19</SP>cm<SP>-3</SP>) super-lattice 304 is epitaxially grown first from the layer having a higher Al composition for 100 periods and then the Si-doped n-type Al<SB>0.4</SB>Ga<SB>0.55</SB>In<SB>0.05</SB>N (thickness: 0.5 μm, Si concentration: 5×10<SP>18</SP>cm<SP>-3</SP>) layer 303 is also epitaxially grown on an n-type 4H-SiC(0001) substrate 305 by an MOCVD method. In order to obtain favorable n-type conductivity, a residual oxygen concentration in the group III nitride semiconductor layer is reduced to 5×10<SP>16</SP>cm<SP>-3</SP>or lower. Subsequently, a Ti/Al/Ti/Au electrode 301 is formed and a Ni/Au electrode 302 is formed on the entire surface of the rear surface of the substrate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明はIII族窒化物半導体素子およびその作製方法に関し、より詳細には、発光波長が200nmから300nmの遠紫外領域であるIII族窒化物半導体素子およびその作製方法に関する。   The present invention relates to a group III nitride semiconductor device and a method for manufacturing the same, and more particularly to a group III nitride semiconductor device having an emission wavelength in the far ultraviolet region of 200 to 300 nm and a method for manufacturing the same.

III族窒化物半導体である窒化アルミニウムガリウムインジウム(Al1-x-yGaxInyN)系半導体素子には、炭化ケイ素(SiC)基板やサファイア(Al2O3)基板が広く用いられている。特に、表1に示すように、SiC基板は、III族窒化物半導体であるGaNやAlNと格子定数が近いため転位等の欠陥生成を抑制することができ、かつ、熱伝導率が高いため高出力動作時に素子の温度上昇も抑制することできる。 A silicon carbide (SiC) substrate or a sapphire (Al 2 O 3 ) substrate is widely used for an aluminum gallium indium nitride (Al 1 -xy Ga x In y N) semiconductor element which is a group III nitride semiconductor. In particular, as shown in Table 1, the SiC substrate has a lattice constant close to that of GaN or AlN, which is a group III nitride semiconductor, so that it can suppress the generation of defects such as dislocations and has high thermal conductivity. It is possible to suppress the temperature rise of the element during the output operation.

Figure 2008071832
Figure 2008071832

一方、SiCはn型およびp型伝導性制御が可能である。例えば、発光ダイオード等のpn接合型素子を作製する場合を考える。図1(A)に、縦型素子構造とその電流分布を示し、図1(B)に、横型素子構造とその電流分布を示す。   On the other hand, SiC can control n-type and p-type conductivity. For example, consider the case of manufacturing a pn junction type element such as a light emitting diode. FIG. 1A shows a vertical element structure and its current distribution, and FIG. 1B shows a horizontal element structure and its current distribution.

図1(A)に示す縦型素子構造は、導電性基板105上にn型層104、p型層103が積層され、p型層103にp型電極101、および導電性基板105にn型電極102が形成された構造となっている。この場合、各層間の界面に垂直な方向を縦方向とすると、電流は導電性基板105、n型層104、p型層103内を縦方向にのみ流れる。   In the vertical element structure shown in FIG. 1A, an n-type layer 104 and a p-type layer 103 are stacked over a conductive substrate 105, a p-type electrode 101 is formed on the p-type layer 103, and an n-type layer is formed on the conductive substrate 105. The electrode 102 is formed. In this case, assuming that the direction perpendicular to the interface between the layers is the vertical direction, current flows only in the vertical direction in the conductive substrate 105, the n-type layer 104, and the p-type layer 103.

図1(B)に示す横型素子構造は、サファイア等の絶縁性基板上に素子を作製する場合にとる構造である。絶縁性基板106上にn型層104、p型層103が積層され、p型層103にp型電極101、およびドライエッチング等により露出されたn型層104にn型電極102が形成された構造となっている。この場合、各層間の界面と水平な方向を横方向とすると、電流がn型層104中を横方向に流れるため素子抵抗が増加し、かつ、電界がn型電極102側に集中して電流分布が不均一になる。特に、デバイス端面に電流が集中するため、素子が破壊され易くなる。   The horizontal element structure shown in FIG. 1B is a structure taken when an element is formed over an insulating substrate such as sapphire. An n-type layer 104 and a p-type layer 103 are stacked on an insulating substrate 106, a p-type electrode 101 is formed on the p-type layer 103, and an n-type electrode 102 is formed on the n-type layer 104 exposed by dry etching or the like. It has a structure. In this case, if the horizontal direction with respect to the interface between the layers is the horizontal direction, the current flows in the n-type layer 104 in the horizontal direction, so that the element resistance increases, and the electric field concentrates on the n-type electrode 102 side and the current flows. Distribution becomes uneven. In particular, since the current concentrates on the device end face, the element is easily destroyed.

一方、導電性のn型SiC基板を用いる場合、n型電極102を基板裏面に形成する縦型構造をとることができるため、素子作製プロセスを簡略化でき、かつ、均一な電流分布が得られる等の利点がある。   On the other hand, when a conductive n-type SiC substrate is used, a vertical structure in which the n-type electrode 102 is formed on the back surface of the substrate can be taken, so that the device manufacturing process can be simplified and a uniform current distribution can be obtained. There are advantages such as.

V.Adivarahan, et al., “250nm AlGaN light-emitting diodes”, App. Phys. Letter, Vol. 85, No.12, September 20, 2004, pp.2175-2177V. Adivarahan, et al., “250nm AlGaN light-emitting diodes”, App. Phys. Letter, Vol. 85, No. 12, September 20, 2004, pp.2175-2177 Akito Kuramata, et al., “Room-Temperature Continuous Wave Operation of InGaN Laser Diodes with Vertical Conducting Structure on SiC Substrate”, Jpn. J. Appl. Phys, Vol. 37, Pt. 2, No. 11B, November 15, 1998, pp.L1373-1375Akito Kuramata, et al., “Room-Temperature Continuous Wave Operation of InGaN Laser Diodes with Vertical Conducting Structure on SiC Substrate”, Jpn. J. Appl. Phys, Vol. 37, Pt. 2, No. 11B, November 15, 1998, pp.L1373-1375 S. Elnfeldt, et al., “Strain relaxation in AlGaN under tensile plane stress”, J. Appl. Phys., Vol. 88, No. 12, December 15, 2000, pp.7029-7036S. Elnfeldt, et al., “Strain relaxation in AlGaN under tensile plane stress”, J. Appl. Phys., Vol. 88, No. 12, December 15, 2000, pp.7029-7036

SiC基板上にIII族窒化物半導体を用いた縦型構造を形成する場合、SiCとIII族窒化物半導体界面にバンドオフセットが生じる。このため、バンドギャップの近いGaNや低Al組成AlGaN(Al組成0.3以下)を用いた青色発光ダイオードや近紫外発光ダイオード等においては、バンドオフセットが小さく、縦方向の電気伝導が得られるため、SiC基板上に素子構造を作製できる。   When a vertical structure using a group III nitride semiconductor is formed on a SiC substrate, a band offset occurs at the interface between the SiC and the group III nitride semiconductor. For this reason, in blue light-emitting diodes and near-ultraviolet light-emitting diodes using GaN with a close band gap or low Al composition AlGaN (Al composition 0.3 or less), the band offset is small and electrical conduction in the vertical direction can be obtained. An element structure can be formed on a substrate.

しかしながら、発光波長が280nm以下となるAl1-x-yGaxInyN(Al組成(1-x-y)は約0.4以上)のバンドギャップは約4.4eV以上であり、SiCとのバンドオフセットは約1eV以上にもなる。特に、発光波長が約210nmのAlNのバンドギャップ約6eVであり、SiCとのバンドオフセットは約3eVにもなる。このような大きなバンドオフセットがIII族窒化物半導体とSiC基板界面に存在すると、SiC基板側からIII族窒化物半導体への電子または正孔の注入は著しく妨げられる。このため、SiC基板上のAlNや高Al組成AlGaN縦型構造においては、縦方向に高い電気伝導性が得られず、SiC基板上にAlNや高Al組成AlGaNを用いた縦型遠赤外発光ダイオード等を作製することは困難であった。 However, Al 1-xy Ga x In y N with an emission wavelength of 280 nm or less (Al composition (1-xy) is about 0.4 or more) has a band gap of about 4.4 eV or more, and the band offset with SiC is about 1 eV. That's it. In particular, the band gap of AlN having an emission wavelength of about 210 nm is about 6 eV, and the band offset with SiC is about 3 eV. If such a large band offset exists at the interface between the group III nitride semiconductor and the SiC substrate, injection of electrons or holes from the SiC substrate side to the group III nitride semiconductor is significantly hindered. For this reason, in the vertical structure of AlN or high Al composition AlGaN on a SiC substrate, high electrical conductivity cannot be obtained in the vertical direction, and vertical far infrared emission using AlN or high Al composition AlGaN on the SiC substrate. It was difficult to produce a diode or the like.

このような理由により、これまでは、遠紫外発光ダイオードは主にサファイア基板上に作製された横型構造であったため、放熱性が悪く、かつ素子抵抗が高い等の理由から高出力動作時に高い熱が発生していた。この発熱はパルス駆動することによって抑制することが可能であるが、電源回路が複雑になる等の実用上の課題があった。   For these reasons, far ultraviolet light emitting diodes have so far been mainly fabricated on a sapphire substrate, so heat dissipation is poor and element resistance is high. Had occurred. Although this heat generation can be suppressed by pulse driving, there are practical problems such as a complicated power supply circuit.

以下に、発光層にAl1-xGaxNを用いた遠紫外発光ダイオードについて例を挙げて説明する(非特許文献1参照)。この例では、発光ダイオードは有機金属気相成長(MOCVD)法により作製されている。図2に、Al1-xGaxNを用いた遠紫外発光ダイオードの構造を示す。基板209にはAl2O3(0001)面を使用しており、この基板209上に、AlNバッファ層208(膜厚0.3μm)、アンドープAlN/Al0.85Ga0.15N超格子層207、n型Al0.72Ga0.28N層206、発光層としてAl0.58Ga0.42N/Al0.65Ga0.35N多重量子井戸層205(3周期)、p型Al0.72Ga0.28N層204(膜厚20nm)、p型GaN層203を成長させた。サファイア(Al2O3)基板209は絶縁性であるため横型構造をとらざるおえず、n型電極202はn型Al0.72Ga0.28N層206上に、p型電極201はp型GaN層203上に形成している。本発光ダイオードの素子サイズは150μm×150μmであり、発光波長は250nmである。 Hereinafter, a far ultraviolet light emitting diode using Al 1-x Ga x N as the light emitting layer will be described by way of example (see Non-Patent Document 1). In this example, the light emitting diode is manufactured by a metal organic chemical vapor deposition (MOCVD) method. FIG. 2 shows the structure of a far-ultraviolet light-emitting diode using Al 1-x Ga x N. An Al 2 O 3 (0001) surface is used for the substrate 209. On this substrate 209, an AlN buffer layer 208 (thickness 0.3 μm), an undoped AlN / Al 0.85 Ga 0.15 N superlattice layer 207, an n-type Al 0.72 Ga 0.28 N layer 206, Al 0.58 Ga 0.42 N / Al 0.65 Ga 0.35 N multiple quantum well layer 205 (3 periods), p-type Al 0.72 Ga 0.28 N layer 204 (film thickness 20 nm), p-type GaN Layer 203 was grown. Since the sapphire (Al 2 O 3 ) substrate 209 is insulative, it does not have to have a horizontal structure. The n-type electrode 202 is on the n-type Al 0.72 Ga 0.28 N layer 206, and the p-type electrode 201 is the p-type GaN layer 203. Formed on top. The element size of the light emitting diode is 150 μm × 150 μm, and the emission wavelength is 250 nm.

このように、発光層にAl1-xGaxNを用いた遠紫外発光ダイオードは横型構造であるので電流分布は不均一になる。また、電流はn型Al0.72Ga0.28N層206中を横方向に流れるため、この横方向抵抗により本素子の素子抵抗は36Ωと高い。さらに、サファイア基板209は熱伝導率が低く、放熱性が悪いため、素子の発熱を抑制するためパルス電流300mA(パルス幅200nsec、デューティー比0.2%)の条件下で駆動している。サファイア基板209は絶縁性であるので、この積層構造のまま縦型構造の素子は作製できない。 Thus, since the far ultraviolet light emitting diode using Al 1-x Ga x N in the light emitting layer has a lateral structure, the current distribution becomes non-uniform. Further, since the current flows in the n-type Al 0.72 Ga 0.28 N layer 206 in the lateral direction, the element resistance of this element is as high as 36Ω due to this lateral resistance. Furthermore, since the sapphire substrate 209 has low thermal conductivity and poor heat dissipation, it is driven under the conditions of a pulse current of 300 mA (pulse width 200 nsec, duty ratio 0.2%) to suppress heat generation of the element. Since the sapphire substrate 209 is insulative, an element having a vertical structure cannot be manufactured with this stacked structure.

また、n型SiC基板上に作製したInGaN青紫色半導体レーザについて例を挙げて説明する(非特許文献2)。この例では、InGaN青紫色半導体レーザはMOCVD法により作製している。まず、n型SiC(0001)基板上に、直接、n型Al0.09Ga0.91Nクラッド層を形成する。その後、n型GaN光ガイド層、InGaN多重量子井戸層、p型Al0.18Ga0.82N電子ブロッキング層、p型GaN光ガイド層、p型Al0.09Ga0.91Nクラッド層、p型GaNコンタクト層を形成している。n型電極はn型SiC基板裏面に形成し、p型電極はp型GaNコンタクト層上に形成している。本素子は縦型構造であり、基板からコンタクト層まで縦方向に電気伝導性がある。本素子は、CW、115mA、10.5Vの条件下において、波長408.2nmでレーザ発振する。 An InGaN blue-violet semiconductor laser fabricated on an n-type SiC substrate will be described with an example (Non-Patent Document 2). In this example, the InGaN blue-violet semiconductor laser is manufactured by the MOCVD method. First, an n-type Al 0.09 Ga 0.91 N cladding layer is formed directly on an n-type SiC (0001) substrate. After that, an n-type GaN optical guide layer, an InGaN multiple quantum well layer, a p-type Al 0.18 Ga 0.82 N electron blocking layer, a p-type GaN optical guide layer, a p-type Al 0.09 Ga 0.91 N cladding layer, and a p-type GaN contact layer are formed. is doing. The n-type electrode is formed on the back surface of the n-type SiC substrate, and the p-type electrode is formed on the p-type GaN contact layer. This element has a vertical structure and is electrically conductive in the vertical direction from the substrate to the contact layer. This device oscillates at a wavelength of 408.2 nm under the conditions of CW, 115 mA, and 10.5 V.

この場合、n型Al0.09Ga0.91Nクラッド層とSiC基板とのバンドオフセットが小さいため、かつ、n型Al0.09Ga0.91Nクラッド層上にそれよりもバンドギャップの小さいInGaN多重量子井戸層を形成しているために縦方向の電気伝導が得られる。しかし、n型Al0.09Ga0.91Nクラッド層上にそれよりもバンドギャップの大きいAlNや高Al組成AlGaNを用いた素子構造を形成すると、これらの間に大きなバンドオフセットが発生して良好な縦方向の電気伝導性を得ることはできない。 In this case, an InGaN multiple quantum well layer with a smaller band gap is formed on the n-type Al 0.09 Ga 0.91 N cladding layer because the band offset between the n-type Al 0.09 Ga 0.91 N cladding layer and the SiC substrate is small. As a result, electrical conduction in the vertical direction can be obtained. However, when an element structure using AlN with a larger band gap or higher Al composition AlGaN is formed on an n-type Al 0.09 Ga 0.91 N cladding layer, a large band offset occurs between them, resulting in good longitudinal direction. The electrical conductivity of cannot be obtained.

ここで、SiC基板上にAlNや高Al組成AlGaNを用いた縦型半導体素子を作製する際、まず、SiC基板上にSiCとバンドオフセットの小さいGaNを形成し、続いて、GaNからAlNや高Al組成AlGaNに向けて徐々にAl組成を増加するAlGaN組成傾斜層を挿入する方法も考えられる。しかし、この場合、GaN上にそれよりも格子定数の小さいAlGaNが形成されるため、強い引張歪みが導入される。このため、AlGaN層の膜厚がある値を超えると、クラックが生じ、十分な品質の発光ダイオード等の半導体素子を作製することはできない。例えば、Al組成0.1においては膜厚が1μmを超えた場合、Al組成0.2においては膜厚が0.4μmを超えた場合、Al組成0.3においては膜厚が0.1μmを超えた場合にクラックが導入される(非特許文献3参照)。一般的に、縦型pn接合構造の膜厚は、0.5μm程度は必要である。つまり、AlGaN組成傾斜層を用いてもクラックが発生するため、AlNや高Al組成AlGaNを用いた縦型半導体素子を作製することはできなかった。   Here, when fabricating a vertical semiconductor device using AlN or a high Al composition AlGaN on a SiC substrate, first, SiC and GaN with a small band offset are formed on the SiC substrate, and then AlN and high GaN are formed from GaN. A method of inserting an AlGaN composition gradient layer that gradually increases the Al composition toward the Al composition AlGaN is also conceivable. However, in this case, since AlGaN having a smaller lattice constant is formed on GaN, a strong tensile strain is introduced. For this reason, when the film thickness of the AlGaN layer exceeds a certain value, cracks occur and a semiconductor element such as a light emitting diode of sufficient quality cannot be manufactured. For example, cracks are introduced when the film thickness exceeds 1 μm for Al composition 0.1, when the film thickness exceeds 0.4 μm for Al composition 0.2, and when the film thickness exceeds 0.1 μm for Al composition 0.3. (See Non-Patent Document 3). Generally, the thickness of the vertical pn junction structure needs to be about 0.5 μm. That is, even if the AlGaN composition gradient layer is used, cracks are generated, so that a vertical semiconductor element using AlN or a high Al composition AlGaN cannot be manufactured.

本発明の目的は、導電性SiC基板上にAlNや高Al組成AlGaNを積層した縦型半導体素子において、クラックを発生させずに高い縦方向電気伝導性を得ることを可能にするIII族窒化物半導体素子およびその作製方法を提供することである。   An object of the present invention is a group III nitride that makes it possible to obtain high vertical conductivity without generating cracks in a vertical semiconductor device in which AlN or high Al composition AlGaN is laminated on a conductive SiC substrate A semiconductor device and a manufacturing method thereof are provided.

このような目的を達成するために、請求項1に記載の発明は、III族窒化物半導体素子において、n型SiCから成る基板と、基板上に形成されたn型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層と、第1の窒化物半導体上に形成されたn型Al1-x-yGaxInyNから成る第2の窒化物半導体層と、基板及び第2の窒化物半導体層にそれぞれ形成されたn型電極とを備え、x≧x1かつy≧y1若しくはx≧x2かつy≧y2であることを特徴とする。 In order to achieve such an object, according to the first aspect of the present invention, there is provided a group III nitride semiconductor device comprising: a substrate made of n-type SiC; and an n-type Al 1-x1-y1 Ga formed on the substrate. x1 In y1 N / Al 1-x2-y2 Ga x2 In y2 N First nitride semiconductor layer composed of N superlattice and n-type Al 1-xy Ga x In y formed on the first nitride semiconductor A second nitride semiconductor layer made of N, and an n-type electrode formed on each of the substrate and the second nitride semiconductor layer, and x ≧ x1 and y ≧ y1 or x ≧ x2 and y ≧ y2. It is characterized by that.

請求項2に記載の発明は、III族窒化物半導体素子において、n型SiCから成る基板と、 基板上に形成されたn型AlN/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層と、第1の窒化物半導体上に形成されたn型AlNから成る第2の窒化物半導体層と、基板及び第2の窒化物半導体層にそれぞれ形成されたn型電極とを備え、Ga組成x2が0.2≦x2≦0.9であり、In組成y2が0≦y2≦0.1であることを特徴とする。 The invention described in claim 2 is a group III nitride semiconductor device comprising a substrate made of n-type SiC and an n-type AlN / Al 1 -x 2 -y 2 Ga x 2 In y 2 N superlattice formed on the substrate. A first nitride semiconductor layer; a second nitride semiconductor layer made of n-type AlN formed on the first nitride semiconductor; and an n-type formed on the substrate and the second nitride semiconductor layer, respectively. And an electrode composition, Ga composition x2 is 0.2 ≦ x2 ≦ 0.9, and In composition y2 is 0 ≦ y2 ≦ 0.1.

請求項3に記載の発明は、III族窒化物半導体素子において、n型SiCから成る基板と、基板上に形成されたn型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層と、第1の窒化物半導体上に形成されたn型Al1-x3-y3Gax3Iny3Nから成る第2の窒化物半導体層と、第2の窒化物半導体上に形成されたAl1-x4-y4Gax4Iny4Nから成る発光層である第3の窒化物半導体層と、第3の窒化物半導体上に形成されたp型Al1-x3-y3Gax3Iny3Nから成る第4の半導体層と、基板に形成されたn型電極と、第4の窒化物半導体層に形成されたp型電極とを備え、0≦x3≦x4≦0.6かつ0≦y3≦y4≦0.1であることを特徴とする。 According to a third aspect of the present invention, there is provided a group III nitride semiconductor device comprising: a substrate made of n-type SiC; and an n-type Al 1-x1-y1 Ga x1 In y1 N / Al 1-x2- formed on the substrate. y2 Ga x2 in y2 n super and the first nitride semiconductor layer made of the grating, the second nitride comprising a first nitride semiconductor n-type formed on Al 1-x3-y3 Ga x3 in y3 n A semiconductor layer, a third nitride semiconductor layer that is a light emitting layer made of Al 1-x4-y4 Ga x4 In y4 N formed on the second nitride semiconductor, and formed on the third nitride semiconductor A p-type Al 1-x3-y3 Ga x3 In y3 N semiconductor layer, an n-type electrode formed on the substrate, and a p-type electrode formed on the fourth nitride semiconductor layer. And 0 ≦ x3 ≦ x4 ≦ 0.6 and 0 ≦ y3 ≦ y4 ≦ 0.1.

請求項4に記載の発明は、III族窒化物半導体素子において、n型SiCから成る基板と、基板上に形成されたn型AlN/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層と、第1の窒化物半導体上に形成されたn型AlNから成る第2の窒化物半導体層と、第2の窒化物半導体上に形成されたAl1-x4-y4Gax4Iny4Nから成る発光層である第3の窒化物半導体層と、第3の窒化物半導体上に形成されたp型AlNから成る第4の窒化物半導体層と、基板に形成されたn型電極と、第4の窒化物半導体層に形成されたp型電極とを備え、Ga組成x2が0.2≦x2≦0.9であり、In組成y2が0≦y2≦0.1であり、Ga組成x4が0≦x4≦0.6であり、In組成y4が0≦y4≦0.1であることを特徴とする。 The invention described in claim 4 is a group III nitride semiconductor device comprising a substrate made of n-type SiC and an n-type AlN / Al 1 -x 2 -y 2 Ga x 2 In y 2 N superlattice formed on the substrate. A first nitride semiconductor layer; a second nitride semiconductor layer made of n-type AlN formed on the first nitride semiconductor; and Al 1-x4- formed on the second nitride semiconductor. A third nitride semiconductor layer which is a light emitting layer made of y4 Ga x4 In y4 N, a fourth nitride semiconductor layer made of p-type AlN formed on the third nitride semiconductor, and a substrate. An n-type electrode and a p-type electrode formed on the fourth nitride semiconductor layer, Ga composition x2 is 0.2 ≦ x2 ≦ 0.9, In composition y2 is 0 ≦ y2 ≦ 0.1, and Ga composition x4 is 0 ≦ x4 ≦ 0.6, and the In composition y4 is 0 ≦ y4 ≦ 0.1.

請求項5に記載の発明は、III族窒化物半導体素子において、p型SiCから成る基板と、基板上に形成されたp型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層と、第1の窒化物半導体層上に形成されたn型Al1-x-yGaxInyNから成る第2の窒化物半導体層と、基板及び第2の窒化物半導体層にそれぞれ形成されたp型電極とを備え、x≧x1かつy≧y1若しくはx≧x2かつy≧y2であることを特徴とする。 The invention according to claim 5 is the group III nitride semiconductor device, wherein the substrate is made of p-type SiC, and the p-type Al 1-x1-y1 Ga x1 In y1 N / Al 1-x2- formed on the substrate. A first nitride semiconductor layer made of y2 Ga x2 In y2 N superlattice and a second nitride semiconductor made of n-type Al 1-xy Ga x In y N formed on the first nitride semiconductor layer And a p-type electrode formed on the substrate and the second nitride semiconductor layer, respectively, wherein x ≧ x1 and y ≧ y1 or x ≧ x2 and y ≧ y2.

請求項6に記載の発明は、III族窒化物半導体素子において、p型SiCから成る基板と、基板上に形成されたp型AlN/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層と、第1の窒化物半導体層上に形成されたn型AlNから成る第2の窒化物半導体層と、基板及び第2の窒化物半導体層にそれぞれ形成されたp型電極とを備え、Ga組成x2が0.2≦x2≦0.9であり、In組成y2が0≦y2≦0.1であることを特徴とする。 The invention described in claim 6 is a group III nitride semiconductor device comprising a substrate made of p-type SiC and a p-type AlN / Al 1 -x 2 -y 2 Ga x 2 In y 2 N superlattice formed on the substrate. A first nitride semiconductor layer; a second nitride semiconductor layer made of n-type AlN formed on the first nitride semiconductor layer; and a p formed on the substrate and the second nitride semiconductor layer, respectively. And a Ga composition x2 is 0.2 ≦ x2 ≦ 0.9, and an In composition y2 is 0 ≦ y2 ≦ 0.1.

請求項7に記載の発明は、III族窒化物半導体素子において、p型SiCから成る基板と、基板上に形成されたp型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層と、第1の窒化物半導体上に形成されたp型Al1-x3-y3Gax3Iny3Nから成る第2の窒化物半導体層と、第2の窒化物半導体層上に形成されたAl1-x4-y4Gax4Iny4Nから成る発光層である第3の窒化物半導体層と、第3の窒化物半導体層上に形成されたn型Al1-x3-y3Gax3Iny3Nから成る第4の窒化物半導体層と、基板に形成されたp型電極と、第4の窒化物半導体層に形成されたn型電極とを備え、0≦x3≦x4≦0.6かつ0≦y3≦y4≦0.1としたことを特徴とする。 The invention according to claim 7 is the group III nitride semiconductor device, wherein the substrate is made of p-type SiC, and p - type Al 1-x1-y1 Ga x1 In y1 N / Al 1-x2- formed on the substrate. y2 Ga x2 in y2 N superlattice consisting of a first nitride semiconductor layer, p-type Al 1-x3-y3 Ga x3 in y3 second nitride consisting of N, which is formed on the first nitride semiconductor A semiconductor layer; a third nitride semiconductor layer which is a light emitting layer made of Al 1-x4-y4 Ga x4 In y4 N formed on the second nitride semiconductor layer; and a third nitride semiconductor layer A fourth nitride semiconductor layer formed of n-type Al 1-x3-y3 Ga x3 In y3 N, a p-type electrode formed on the substrate, and an n-type formed on the fourth nitride semiconductor layer A mold electrode, wherein 0 ≦ x3 ≦ x4 ≦ 0.6 and 0 ≦ y3 ≦ y4 ≦ 0.1.

請求項8に記載の発明は、III族窒化物半導体素子において、p型SiCから成る基板と、基板上に形成されたp型AlN/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層と、第1の窒化物半導体上に形成されたp型AlNから成る第2の窒化物半導体層と、第2の窒化物半導体層上に形成されたAl1-x4-y4Gax4Iny4Nから成る発光層である第3の窒化物半導体層と、第3の窒化物半導体層上に形成されたn型AlNから成る第4の窒化物半導体層と、基板に形成されたp型電極と、第4の窒化物半導体層に形成されたn型電極とを備え、Ga組成x2が0.2≦x2≦0.9であり、In組成y2が0≦y2≦0.1であり、Ga組成x4が0≦x4≦0.6であり、In組成y4が0≦y4≦0.1であることを特徴とする。 The invention described in claim 8 is a group III nitride semiconductor device comprising a substrate made of p-type SiC and a p-type AlN / Al 1 -x 2 -y 2 Ga x 2 In y 2 N superlattice formed on the substrate. A first nitride semiconductor layer; a second nitride semiconductor layer made of p-type AlN formed on the first nitride semiconductor; and Al 1-x4 formed on the second nitride semiconductor layer. a third nitride semiconductor layer that is a light-emitting layer made of -y4 Ga x4 In y4 N, a fourth nitride semiconductor layer made of n-type AlN formed on the third nitride semiconductor layer, and a substrate A p-type electrode formed and an n-type electrode formed on the fourth nitride semiconductor layer, Ga composition x2 is 0.2 ≦ x2 ≦ 0.9, In composition y2 is 0 ≦ y2 ≦ 0.1, The Ga composition x4 is 0 ≦ x4 ≦ 0.6, and the In composition y4 is 0 ≦ y4 ≦ 0.1.

請求項9に記載の発明は、請求項1乃至8のいずれかに記載のIII族窒化物半導体素子であって、第1の窒化物半導体層は、平均Al組成が基板から第2の窒化物半導体層に向けて増加していることを特徴とする。   The invention according to claim 9 is the group III nitride semiconductor device according to any one of claims 1 to 8, wherein the first nitride semiconductor layer has an average Al composition from the substrate to the second nitride. It is characterized by increasing toward the semiconductor layer.

請求項10に記載の発明は、n型SiCから成る基板上にAlGaInNから成る窒化物半導体を積層したIII族窒化物半導体素子の作製方法であって、基板上にn型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層を形成するステップであって、Al組成の高い層から先に形成する第1の窒化物半導体層を形成するステップと、第1の窒化物半導体層上にn型Al1-x-yGaxInyNから成る第2の窒化物半導体層を形成するステップと、基板及び第2の窒化物半導体層にn型電極をそれぞれ形成するステップとを有することを特徴とする。 The invention according to claim 10 is a method for manufacturing a group III nitride semiconductor device in which a nitride semiconductor made of AlGaInN is stacked on a substrate made of n-type SiC, wherein the n-type Al 1-x1-y1 is formed on the substrate. Ga x1 In y1 N / Al 1-x2-y2 A step of forming a first nitride semiconductor layer composed of Ga x2 In y2 N superlattice, the first nitridation formed first from a layer with a high Al composition Forming a nitride semiconductor layer; forming a second nitride semiconductor layer made of n-type Al 1-xy Ga x In y N on the first nitride semiconductor layer; and a substrate and a second nitride Forming n-type electrodes on the physical semiconductor layer.

請求項11に記載の発明は、p型SiCから成る基板上にAlGaInNから成る窒化物半導体を積層したIII族窒化物半導体素子の作製方法であって、基板上にp型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層を形成するステップであって、Al組成の高い層から先に形成する第1の窒化物半導体層を形成するステップと、第1の窒化物半導体層上にp型Al1-x-yGaxInyNから成る第2の窒化物半導体層を形成するステップと、基板及び第2の窒化物半導体層にp型電極をそれぞれ形成するステップとを有することを特徴とする。 The invention according to claim 11 is a method of manufacturing a group III nitride semiconductor device in which a nitride semiconductor made of AlGaInN is stacked on a substrate made of p-type SiC, and the p-type Al 1-x1-y1 is formed on the substrate. Ga x1 In y1 N / Al 1-x2-y2 A step of forming a first nitride semiconductor layer composed of Ga x2 In y2 N superlattice, the first nitridation formed first from a layer with a high Al composition Forming a nitride semiconductor layer, forming a second nitride semiconductor layer made of p-type Al 1-xy Ga x In y N on the first nitride semiconductor layer, a substrate and a second nitride Forming a p-type electrode on each physical semiconductor layer.

請求項12に記載の発明は、n型SiC基板上にAlGaInNから成る窒化物半導体を積層したIII族窒化物半導体素子の作製方法であって、SiC基板上にn型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層を形成するステップであって、Al組成の高い層から先に形成する第1の窒化物半導体層を形成するステップと、第1の窒化物半導体層上にn型Al1-x3-y3Gax3Iny3Nから成る第2の窒化物半導体層を形成するステップと、第2の窒化物半導体層上にAl1-x4-y4Gax4Iny4Nから成る発光層である第3の窒化物半導体層を形成するステップと、第3の窒化物半導体上にp型Al1-x3-y3Gax3Iny3Nから成る第4の半導体層を形成するステップと基板にn型電極を形成するステップと第4の窒化物半導体層にp型電極を形成するステップとを有することを特徴とする。 The invention according to claim 12 is a method for manufacturing a group III nitride semiconductor device in which a nitride semiconductor made of AlGaInN is stacked on an n-type SiC substrate, and the n-type Al 1-x1-y1 Ga is formed on the SiC substrate. x1 In y1 N / Al 1-x2-y2 Ga x2 In y2 N forming a first nitride semiconductor layer comprising a superlattice, the first nitride formed first from a layer having a high Al composition forming forming a semiconductor layer, a second nitride semiconductor layer made of n-type Al 1-x3-y3 Ga x3 in y3 n in the first nitride semiconductor layer, a second nitride Forming a third nitride semiconductor layer which is a light emitting layer made of Al 1-x4-y4 Ga x4 In y4 N on the semiconductor layer; and p-type Al 1-x3-y3 on the third nitride semiconductor characterized by a step of forming a p-type electrode on the Ga x3 an in y3 step and the fourth nitride semiconductor layer forming the n-type electrode on the step and the substrate forming a fourth semiconductor layer made of n To.

請求項13に記載の発明は、p型SiC基板上にAlGaInNから成る窒化物半導体を積層したIII族窒化物半導体素子の作製方法であって、SiC基板上にp型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層を形成するステップであって、Al組成の高い層から先に形成する第1の窒化物半導体層を形成するステップと、第1の窒化物半導体層上にp型Al1-x3-y3Gax3Iny3Nから成る第2の窒化物半導体層を形成するステップと、第2の窒化物半導体層上にAl1-x4-y4Gax4Iny4Nから成る発光層である第3の窒化物半導体層を形成するステップと、第3の窒化物半導体上にn型Al1-x3-y3Gax3Iny3Nから成る第4の半導体層を形成するステップと基板にp型電極を形成するステップと第4の窒化物半導体層にn型電極を形成するステップとを有することを特徴とする。 The invention according to claim 13 is a method of manufacturing a group III nitride semiconductor device in which a nitride semiconductor made of AlGaInN is stacked on a p-type SiC substrate, and the p-type Al 1-x1-y1 Ga is formed on the SiC substrate. x1 In y1 N / Al 1-x2-y2 Ga x2 In y2 N forming a first nitride semiconductor layer comprising a superlattice, the first nitride formed first from a layer having a high Al composition forming forming a semiconductor layer, a second nitride semiconductor layer made of p-type Al 1-x3-y3 Ga x3 in y3 N in the first nitride semiconductor layer, a second nitride Forming a third nitride semiconductor layer which is a light emitting layer made of Al 1-x4-y4 Ga x4 In y4 N on the semiconductor layer; and n-type Al 1-x3-y3 on the third nitride semiconductor characterized by a step of forming a step and fourth n-type electrode on the nitride semiconductor layer forming the p-type electrode on the step and the substrate forming a fourth semiconductor layer made of Ga x3 in y3 n To.

本発明によれば、SiC基板とIII族窒化物半導体(Al1-x-yGaxInyN)の間に、Al1-x1-y1Gax1Iny1N/Al1-x2-y2Gax2Iny2N超格子を挿入したことにより、クラックがなく、高い縦方向の電気伝導性を有する縦型半導体素子が得られる。このため、SiC基板上にAlNや高Al組成AlGaNを積層した縦型半導体素子が可能になり、発熱量の多い高直流電流駆動条件下でも安定に動作できる利点がある。 According to the present invention, Al 1-x1-y1 Ga x1 In y1 N / Al 1-x2-y2 Ga x2 In is provided between the SiC substrate and the group III nitride semiconductor (Al 1-xy Ga x In y N). By inserting the y2 N superlattice, a vertical semiconductor element free from cracks and having high electrical conductivity in the vertical direction can be obtained. For this reason, a vertical semiconductor element in which AlN or a high Al composition AlGaN is laminated on a SiC substrate becomes possible, and there is an advantage that it can operate stably even under high DC current driving conditions with a large amount of heat generation.

本発明は、縦型素子構造において、n型SiC基板とn型III族窒化物半導体(Al1-x-yGaxInyN)の間に、n型Al1-x1-y1Gax1Iny1N/Al1-x2-y2Gax2Iny2N超格子を挿入したことを特徴し、この点において従来技術とは異なる。高直流電流駆動条件下でも安定に動作可能にする超格子の組成は、後述するように特定の範囲に限られる。 The present invention provides an n-type Al 1-x1-y1 Ga x1 In y1 N between an n-type SiC substrate and an n-type Group III nitride semiconductor (Al 1-xy Ga x In y N) in a vertical device structure. / Al 1 -x2-y2 Ga x2 In y2 N superlattice is inserted, which is different from the prior art. The composition of the superlattice that enables stable operation even under high direct current drive conditions is limited to a specific range as described later.

SiC基板とIII族窒化物半導体Al1-x-yGaxInyNの間に、Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子を挿入した場合には、クラックを生じさせずに高い縦方向の電気伝導性が得られる。この構造をSiC基板上にAlNや高Al組成AlGaNを積層した縦型遠紫外半導体発光素子に適用すれば、均一な電流分布が得られ、素子抵抗を低減し、かつ、熱のこもりも抑制できる。その結果、発熱量の多い高直流電流駆動条件下でも安定に動作する遠紫外半導体発光素子を作成することができる。 When Al 1-x1-y1 Ga x1 In y1 N / Al 1-x2-y2 Ga x2 In y2 N superlattice is inserted between SiC substrate and Group III nitride semiconductor Al 1-xy Ga x In y N High electrical conductivity in the vertical direction can be obtained without causing cracks. If this structure is applied to a vertical far ultraviolet semiconductor light emitting device in which AlN or high Al composition AlGaN is stacked on a SiC substrate, a uniform current distribution can be obtained, device resistance can be reduced, and thermal accumulation can be suppressed. . As a result, it is possible to produce a far-ultraviolet semiconductor light-emitting element that operates stably even under high DC current driving conditions with a large amount of heat generation.

後述する実施形態1〜9のIII族窒化物半導体は、有機金属気相成長法(MOCVD法)によりSiC基板上に形成する。n型4H-SiC(0001)基板を用いる場合は、基板の厚さが100μm程度となるように研磨する。一方、p型6H-SiC(0001)基板を用いる場合は、基板厚さが50μm程度となるように研磨する。Al原料としてトリメチルアルミニウム(TMA)、Ga原料としてトリメチルガリウム(TMG)、In原料としてトリメチルインジウム(TMIn)、N原料としてアンモニア(NH3)、シリコン(Si)ドーパント原料としてシラン(SiH4)、Mgドーパント原料としてビスシクロペンタジエニルマグネシウム(Cp2Mg)をそれぞれ用いる。各薄膜の成長温度は1300℃とする。 The group III nitride semiconductors of Embodiments 1 to 9 described later are formed on a SiC substrate by metal organic chemical vapor deposition (MOCVD method). When an n-type 4H—SiC (0001) substrate is used, polishing is performed so that the thickness of the substrate is about 100 μm. On the other hand, when a p-type 6H—SiC (0001) substrate is used, polishing is performed so that the substrate thickness is about 50 μm. Trimethylaluminum (TMA) as the Al source, trimethylgallium (TMG) as the Ga source, trimethylindium (TMIn) as the In source, ammonia (NH 3 ) as the N source, silane (SiH 4 ) as the silicon (Si) dopant source, Mg Biscyclopentadienyl magnesium (Cp 2 Mg) is used as a dopant material. The growth temperature of each thin film is 1300 ° C.

(実施形態1)
・n型AlGaInN
本実施形態に係るn型SiC基板とn型III族窒化物半導体(Al1-x-yGaxInyN)の間にn型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子を挿入したことを特徴とする縦型素子の構造と電気伝導特性について、図面を参照しながら詳しく説明する。ここでは、比較のため、本実施形態に係る素子の他に、図3(B)、(C)に示す構造を有する素子の電気伝導特性についても述べる。まず、各素子の構造とその作製方法について説明する。
(Embodiment 1)
・ N-type AlGaInN
N - type Al 1-x1-y1 Ga x1 In y1 N / Al 1-x2- between the n-type SiC substrate and the n-type group III nitride semiconductor (Al 1-xy Ga x In y N) according to this embodiment The structure and electrical conduction characteristics of the vertical element characterized by inserting a y2 Ga x2 In y2 N superlattice will be described in detail with reference to the drawings. Here, for comparison, in addition to the element according to the present embodiment, the electric conduction characteristics of the element having the structure shown in FIGS. 3B and 3C will be described. First, the structure of each element and the manufacturing method thereof will be described.

図3(A)に、n型SiC基板とn型III族窒化物半導体(Al1-x-yGaxInyN)の間にn型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子を挿入した縦型素子の構造を示す。まず、MOCVD法により、n型4H-SiC(0001)基板305上に、Siドープn型Al0.8Ga0.15In0.05N(膜厚3nm、Si濃度3×1019cm-3)/Al0.5Ga0.45In0.05N (膜厚3nm、Si濃度3×1019cm-3) 超格子を100周期積層した超格子層304、Siドープn型Al0.4Ga0.55In0.05N (膜厚0.5μm、Si濃度5×1018cm-3) 層303をエピタキシャル成長させる。なお、良好なn型伝導性を得るために、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下に低減する。また、SiC基板305上には、超格子層304のうちAl組成の高いSiドープn型Al0.8Ga0.15In0.05N層から先に形成する。続いて、Siドープn型Al0.4Ga0.55In0.05N層303上にTi/Al/Ti/Au電極301(サイズ100μm×100μm)を形成し、SiC基板裏面全面にNi/Au電極302を形成する。 Fig. 3 (A) shows n-type Al 1-x1-y1 Ga x1 In y1 N / Al 1- between n-type SiC substrate and n-type Group III nitride semiconductor (Al 1-xy Ga x In y N). The structure of a vertical element in which an x2-y2 Ga x2 In y2 N superlattice is inserted is shown. First, by MOCVD, on an n-type 4H—SiC (0001) substrate 305, Si-doped n-type Al 0.8 Ga 0.15 In 0.05 N (film thickness 3 nm, Si concentration 3 × 10 19 cm −3 ) / Al 0.5 Ga 0.45 In 0.05 N (film thickness 3 nm, Si concentration 3 × 10 19 cm −3 ) Superlattice layer 304 with 100 superlattice layers, Si-doped n-type Al 0.4 Ga 0.55 In 0.05 N (film thickness 0.5 μm, Si concentration 5 × 10 18 cm -3 ) The layer 303 is epitaxially grown. In order to obtain good n-type conductivity, the residual oxygen concentration in the group III nitride semiconductor layer is reduced to 5 × 10 16 cm −3 or less. On the SiC substrate 305, the Si-doped n-type Al 0.8 Ga 0.15 In 0.05 N layer having a high Al composition in the superlattice layer 304 is formed first. Subsequently, a Ti / Al / Ti / Au electrode 301 (size 100 μm × 100 μm) is formed on the Si-doped n-type Al 0.4 Ga 0.55 In 0.05 N layer 303, and a Ni / Au electrode 302 is formed on the entire back surface of the SiC substrate. .

図3(B)に、n型SiC基板とn型III族窒化物半導体(Al1-x-yGaxInyN)の間にn型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子を挿入した横型素子の構造を示す。まず、MOCVD法により、n型4H-SiC(0001)基板305上に、Siドープn型Al0.8Ga0.15In0.05N(膜厚3nm、Si濃度3×1019cm-3)/Al0.5Ga0.45In0.05N(膜厚3nm、Si濃度3×1019cm-3)超格子を100周期積層した超格子層304、Siドープn型Al0.4Ga0.55In0.05N(膜厚0.5μm、Si濃度5×1018cm-3)層303をエピタキシャル成長させる。なお、良好なn型伝導性を得るために、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下に低減する。また、SiC基板上には、超格子層304のうちAl組成の高いSiドープn型Al0.8Ga0.15In0.05N層から先に形成する。続いて、Siドープn型Al0.4Ga0.55In0.05N層303上にTi/Al/Ti/Au電極301(サイズ100μm×100μm)を形成し、その電極周辺部をエッチングにより除去し、Siドープn型Al0.4Ga0.55In0.05N層303のエッチングを施した面上にTi/Al/Ti/Au電極302を形成する。電極302をこのような位置に形成したのは、LEDに近い構造で縦方向と横方向の電気伝導の影響を調べるためである。 Figure 3 (B) shows an n-type Al 1-x1-y1 Ga x1 In y1 N / Al 1- between an n-type SiC substrate and an n-type Group III nitride semiconductor (Al 1-xy Ga x In y N). The structure of a lateral element in which an x2-y2 Ga x2 In y2 N superlattice is inserted is shown. First, by MOCVD, on an n-type 4H—SiC (0001) substrate 305, Si-doped n-type Al 0.8 Ga 0.15 In 0.05 N (film thickness 3 nm, Si concentration 3 × 10 19 cm −3 ) / Al 0.5 Ga 0.45 In 0.05 N (thickness 3 nm, Si concentration 3 × 10 19 cm -3 ) superlattice layer 304 with 100 superlattice layers, Si-doped n-type Al 0.4 Ga 0.55 In 0.05 N (thickness 0.5 μm, Si concentration 5 X10 18 cm -3 ) layer 303 is grown epitaxially. In order to obtain good n-type conductivity, the residual oxygen concentration in the group III nitride semiconductor layer is reduced to 5 × 10 16 cm −3 or less. On the SiC substrate, the Si-doped n-type Al 0.8 Ga 0.15 In 0.05 N layer having a high Al composition in the superlattice layer 304 is formed first. Subsequently, a Ti / Al / Ti / Au electrode 301 (size 100 μm × 100 μm) is formed on the Si-doped n-type Al 0.4 Ga 0.55 In 0.05 N layer 303, and the periphery of the electrode is removed by etching. A Ti / Al / Ti / Au electrode 302 is formed on the etched surface of the type Al 0.4 Ga 0.55 In 0.05 N layer 303. The reason why the electrode 302 is formed at such a position is to investigate the influence of electrical conduction in the vertical and horizontal directions with a structure close to that of an LED.

図3(C)に、超格子を挿入していない場合のn型SiC基板上にn型III族窒化物半導体(Al1-x-yGaxInyN)を積層した縦型素子の構造を示す。まず、MOCVD法により、n型4H-SiC(0001)基板305上に、直接、Siドープn型Al0.4Ga0.55In0.05N(膜厚0.5μm、Si濃度5×1018cm-3)層303をエピタキシャル成長させる。なお、良好なn型伝導性を得るために、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下に低減する。続いて、Siドープn型Al0.4Ga0.55In0.05N層303上にTi/Al/Ti/Au電極301(サイズ100μm×100μm)を形成し、SiC基板305裏面全面にNi/Au電極302を形成する。 Fig. 3 (C) shows the structure of a vertical device in which an n-type group III nitride semiconductor (Al 1-xy Ga x In y N) is stacked on an n-type SiC substrate when no superlattice is inserted. . First, an Si-doped n-type Al 0.4 Ga 0.55 In 0.05 N (film thickness 0.5 μm, Si concentration 5 × 10 18 cm −3 ) layer 303 is directly formed on the n-type 4H—SiC (0001) substrate 305 by MOCVD. Is epitaxially grown. In order to obtain good n-type conductivity, the residual oxygen concentration in the group III nitride semiconductor layer is reduced to 5 × 10 16 cm −3 or less. Subsequently, a Ti / Al / Ti / Au electrode 301 (size 100 μm × 100 μm) is formed on the Si-doped n-type Al 0.4 Ga 0.55 In 0.05 N layer 303, and a Ni / Au electrode 302 is formed on the entire back surface of the SiC substrate 305. To do.

図4に、図3(A)、(B)、(C)に示す構造を有する各素子の電流−電圧特性を示す。図3(A)の超格子を挿入した縦型構造の場合、良好なオーミック特性を有する縦方向の電気伝導性が得られる。また、素子抵抗も2Ωと低い。一方、図3(B)の超格子を挿入した横型構造の場合、オーミック特性は得られるが、素子抵抗は25Ωと高くなる。また、図3(C)の超格子を挿入しない縦型素子の場合、n型SiC基板305/Siドープn型Al0.4Ga0.55In0.05N層303界面のバンドオフセットに起因して、電流−電圧特性は整流性を示し、良好なオーミック特性は得られない。以上のように、超格子層304を挿入することによってSiC基板305の縦型素子においても電流−電圧特性がオーミック性になり、かつ素子抵抗を低減できる。 FIG. 4 shows current-voltage characteristics of each element having the structure shown in FIGS. 3 (A), (B), and (C). In the case of the vertical structure in which the superlattice shown in FIG. 3A is inserted, vertical electric conductivity having good ohmic characteristics can be obtained. In addition, the element resistance is as low as 2Ω. On the other hand, in the case of a lateral structure in which the superlattice shown in FIG. Further, in the case of the vertical element in which the superlattice of FIG. 3C is not inserted, the current-voltage is caused by the band offset at the interface of the n-type SiC substrate 305 / Si-doped n-type Al 0.4 Ga 0.55 In 0.05 N layer 303. The characteristic shows a rectifying property and a good ohmic characteristic cannot be obtained. As described above, by inserting the superlattice layer 304, the current-voltage characteristic becomes ohmic even in the vertical element of the SiC substrate 305, and the element resistance can be reduced.

また、n型SiC基板とn型III族窒化物半導体(Al1-x-yGaxInyN)の間にn型Al1-x1-y1Gax1Iny1N/Al1-x2-y2Gax2Iny2N超格子を挿入する際、x≧x1かつy≧y1もしくはx≧x2かつy≧y2とすることで、n型III族窒化物半導体の膜厚10μm程度まで厚くしてもクラックは発生しない。x≧x1かつy≧y1もしくはx≧x2かつy≧y2とすることで、超格子の平均的な格子定数よりもn型III族窒化物半導体の格子定数の方が大きくなり、n型III族窒化物半導体には圧縮歪みが導入される。つまり、導入される歪みはクラックの原因である引張歪みとは逆方向の歪みであるので、n型III族窒化物半導体にクラックは発生しない。 Also, n - type Al 1-x1-y1 Ga x1 In y1 N / Al 1-x2-y2 Ga x2 between n-type SiC substrate and n-type group III nitride semiconductor (Al 1-xy Ga x In y N) When inserting In y2 N superlattice, if x ≧ x1 and y ≧ y1 or x ≧ x2 and y ≧ y2, cracks will occur even if the thickness of the n-type group III nitride semiconductor is increased to about 10 μm do not do. By setting x ≧ x1 and y ≧ y1 or x ≧ x2 and y ≧ y2, the lattice constant of the n-type group III nitride semiconductor is larger than the average lattice constant of the superlattice, and the n-type group III Compressive strain is introduced into the nitride semiconductor. That is, since the strain to be introduced is a strain in a direction opposite to the tensile strain that causes the crack, no crack is generated in the n-type group III nitride semiconductor.

超格子を挿入することで高い電気伝導性が得られる理由をn型SiC上にn型AlNを形成した場合を例にして説明する。図5(A)にn型SiC上にn型AlNを形成した場合、図5(B)にn型SiCとn型AlNの間にn型AlN/AlGaInN超格子を挿入した場合のエネルギーバンドの概略図をそれぞれ示す。n型SiC上にn型AlNを形成した場合、図5(A)に示すようにn型SiCとn型AlNの界面に大きな伝導帯バンドオフセットが存在し、n型SiCから電子をn型AlNに注入することは困難である。このため、n型SiCとn型AlNとの間で高い電気伝導性が得られない。一方、n型SiCとn型AlNの間にn型AlN/AlGaInN超格子を挿入した場合、図5(B)に示すように、まず、n型SiCからトンネル効果により電子を超格子層の量子準位に注入できる。そして、超格子層の量子準位とn型AlNの伝導帯のエネルギー差がSiCとAlNの伝導帯オフセットと比べて小さいため、超格子層からn型AlN層に電子を効率良く注入できる。このため、n型SiCとn型AlNとの間でも高い電気伝導性が得られる。   The reason why high electrical conductivity can be obtained by inserting a superlattice will be described by taking n-type AlN as an example on n-type SiC. When n-type AlN is formed on n-type SiC in FIG. 5 (A), the energy band when n-type AlN / AlGaInN superlattice is inserted between n-type SiC and n-type AlN in FIG. 5 (B). Each schematic is shown. When n-type AlN is formed on n-type SiC, there is a large conduction band offset at the interface between n-type SiC and n-type AlN, as shown in FIG. 5A, and electrons are transferred from n-type SiC to n-type AlN. It is difficult to inject. For this reason, high electrical conductivity cannot be obtained between n-type SiC and n-type AlN. On the other hand, when an n-type AlN / AlGaInN superlattice is inserted between n-type SiC and n-type AlN, as shown in FIG. 5B, first, electrons are transferred from the n-type SiC by the tunnel effect to the quantum of the superlattice layer. Can be injected into the level. Since the energy difference between the quantum level of the superlattice layer and the conduction band of n-type AlN is smaller than the conduction band offset of SiC and AlN, electrons can be efficiently injected from the superlattice layer into the n-type AlN layer. For this reason, high electrical conductivity can be obtained even between n-type SiC and n-type AlN.

加えて、高いトンネル確率を得るには、超格子を形成する層のうち、バンドギャップの大きい層、つまり、Al組成の高い層の膜厚を5nm以下にしてポテンシャル障壁を所定の厚さ以下にすることが望ましい。   In addition, in order to obtain a high tunnel probability, among the layers forming the superlattice, the layer with a large band gap, i.e., the layer with a high Al composition is made 5 nm or less in thickness and the potential barrier is made a predetermined thickness or less. It is desirable to do.

このようにして本実施形態は、n型SiC基板上に縦方向の高い電気伝導性を有する高Al組成AlGaInN縦型半導体素子を実現できる。   Thus, this embodiment can realize a high Al composition AlGaInN vertical semiconductor element having high electrical conductivity in the vertical direction on an n-type SiC substrate.

(実施形態2)
実施形態1では図3(A)の超格子を挿入した縦型素子構造において、SiC基板からIII族窒化物半導体に向けて、超格子の平均Al組成を徐々に増加させた構造を作製可能にしている。本実施形態では、超格子の平均Al組成を増加させるため、SiC基板からn型III族窒化物半導体に向けて、Siドープn型Al1-x1-y1Gax1Iny1N/Al1-x2-y2Gax2Iny2N超格子のうち、Al1-x2-y2Gax2Iny2N層の膜厚を20nmから1nmへと1周期毎に徐々に減少させる。但し、その他の条件は同一である。すなわち、まず、MOCVD法により、n型4H-SiC(0001)基板上に、Siドープn型Al0.8Ga0.15In0.05N(膜厚3nm、Si濃度3×1019cm-3)/Al0.5Ga0.45In0.05N (膜厚20nmから1nmへと1周期毎に徐々に減少、Si濃度3×1019cm-3) 超格子を100周期、Siドープn型Al0.4Ga0.55In0.05N (膜厚0.5μm、Si濃度5×1018cm-3) 層をエピタキシャル成長させる。なお、良好なn型伝導性を得るために、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下に低減する。また、SiC基板上には、超格子層のうちAl組成の高いSiドープn型Al0.8Ga0.15In0.05N層から先に形成する。続いて、Siドープn型Al0.4Ga0.55In0.05N層上にTi/Al/Ti/Au電極(サイズ100μm×100μm)を形成し、SiC基板裏面全面にNi/Au電極を形成する。この構造の素子抵抗は1Ωであり、図3(A)に示した超格子の平均Al組成が一定の場合よりも、オーミック性が良く、かつ素子抵抗が半分に低減する。
(Embodiment 2)
In the first embodiment, in the vertical element structure in which the superlattice of FIG. 3A is inserted, a structure in which the average Al composition of the superlattice is gradually increased from the SiC substrate toward the group III nitride semiconductor can be manufactured. ing. In this embodiment, in order to increase the average Al composition of the superlattice, from the SiC substrate toward the n-type group III nitride semiconductor, the Si-doped n-type Al 1-x1-y1 Ga x1 In y1 N / Al 1-x2 In the -y2 Ga x2 In y2 N superlattice, the thickness of the Al 1 -x2 -y2 Ga x2 In y2 N layer is gradually decreased from 20 nm to 1 nm every cycle. However, other conditions are the same. That is, first, by MOCVD, an Si-doped n-type Al 0.8 Ga 0.15 In 0.05 N (film thickness 3 nm, Si concentration 3 × 10 19 cm −3 ) / Al 0.5 Ga on an n-type 4H—SiC (0001) substrate. 0.45 In 0.05 N (film thickness gradually decreased from 20 nm to 1 nm every period, Si concentration 3 × 10 19 cm -3 ) 100 periods of superlattice, Si-doped n-type Al 0.4 Ga 0.55 In 0.05 N (film thickness A 0.5 μm, Si concentration 5 × 10 18 cm −3 ) layer is epitaxially grown. In order to obtain good n-type conductivity, the residual oxygen concentration in the group III nitride semiconductor layer is reduced to 5 × 10 16 cm −3 or less. On the SiC substrate, a Si-doped n-type Al 0.8 Ga 0.15 In 0.05 N layer having a high Al composition is formed first from the superlattice layer. Subsequently, a Ti / Al / Ti / Au electrode (size 100 μm × 100 μm) is formed on the Si-doped n-type Al 0.4 Ga 0.55 In 0.05 N layer, and a Ni / Au electrode is formed on the entire back surface of the SiC substrate. The element resistance of this structure is 1Ω, which is better than the case where the average Al composition of the superlattice shown in FIG. 3A is constant, and the element resistance is reduced to half.

この理由を、実施形態1の図5(a)、(b)に準じて説明する。図5(C)に、SiC基板からn型III族窒化物半導体に向けて超格子の膜厚を減少させた場合のエネルギーバンドの概略図を示す。超格子を形成する層のうち、Al組成の低い層の膜厚を減少させ、超格子の平均Al組成を増加させると量子準位が上昇し、超格子の擬似的なバンドギャップが大きくなる。これにより、超格子層の量子準位とn型AlNの伝導帯のエネルギー差がn型AlNに近づくにつれてより小さくなるため、超格子層からn型AlN層に電子をさらに効率良く注入できる。このため、n型SiCとn型AlNとの間の電気伝導性が実施形態1よりもさらに向上する。   The reason for this will be described according to FIGS. 5A and 5B of the first embodiment. FIG. 5C shows a schematic diagram of the energy band when the thickness of the superlattice is reduced from the SiC substrate toward the n-type group III nitride semiconductor. Among the layers forming the superlattice, when the film thickness of the layer having a low Al composition is decreased and the average Al composition of the superlattice is increased, the quantum level rises and the pseudo band gap of the superlattice increases. Thereby, since the energy difference between the quantum level of the superlattice layer and the conduction band of n-type AlN becomes smaller as it approaches n-type AlN, electrons can be more efficiently injected from the superlattice layer into the n-type AlN layer. For this reason, the electrical conductivity between n-type SiC and n-type AlN is further improved as compared with the first embodiment.

(実施形態3)
・n型AlN
本実施形態に係るn型SiC基板とn型AlNの間に、n型AlN/ Al1-x2-y2Gax2Iny2N超格子を挿入したことを特徴とする縦型素子の構造と電気伝導特性について、図面を参照しながら詳しく説明する。また、比較のため、図6(B)、(C)に示す構造を有する素子の電気伝導性も評価した。まず、各素子の構造とその作製方法について説明する。
(Embodiment 3)
・ N-type AlN
Structure and electrical conduction of a vertical element characterized in that an n-type AlN / Al 1-x2-y2 Ga x2 In y2 N superlattice is inserted between the n-type SiC substrate and the n-type AlN according to this embodiment The characteristics will be described in detail with reference to the drawings. For comparison, the electrical conductivity of the element having the structure shown in FIGS. 6B and 6C was also evaluated. First, the structure of each element and the manufacturing method thereof will be described.

図6(A)に、n型SiC基板とn型AlNの間に、n型AlN/ Al1-x2-y2Gax2Iny2N超格子を挿入した縦型素子の構造を示す。まず、MOCVD法により、n型4H-SiC(0001)基板605上に、Siドープn型AlN(膜厚3nm、Si濃度3×1019cm-3)/Al0.5Ga0.45In0.05N(膜厚3nm、Si濃度3×1019cm-3)超格子を100周期積層した超格子層604、Siドープn型AlN(膜厚0.5μm、Si濃度5×1018cm-3)層603をエピタキシャル成長させる。なお、良好なn型伝導性を得るために、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下に低減している。また、SiC基板605上には、超格子層604のうちAl組成の高いSiドープn型AlN層から先に形成する。続いて、Siドープn型AlN層603上にTi/Al/Ti/Au電極(サイズ100μm×100μm)を形成し、SiC基板605裏面全面にNi/Au電極を形成する。 FIG. 6A shows the structure of a vertical element in which an n-type AlN / Al 1-x2-y2 Ga x2 In y2 N superlattice is inserted between an n-type SiC substrate and n-type AlN. First, by MOCVD, on an n-type 4H-SiC (0001) substrate 605, Si-doped n-type AlN (film thickness 3 nm, Si concentration 3 × 10 19 cm −3 ) / Al 0.5 Ga 0.45 In 0.05 N (film thickness 3 nm, Si concentration 3 × 10 19 cm −3 ) Superlattice layer 604 in which 100 superlattices are stacked, and Si-doped n-type AlN (film thickness 0.5 μm, Si concentration 5 × 10 18 cm −3 ) layer 603 are epitaxially grown . In order to obtain good n-type conductivity, the residual oxygen concentration in the group III nitride semiconductor layer is reduced to 5 × 10 16 cm −3 or less. On the SiC substrate 605, the Si-doped n-type AlN layer having a high Al composition in the superlattice layer 604 is formed first. Subsequently, a Ti / Al / Ti / Au electrode (size 100 μm × 100 μm) is formed on the Si-doped n-type AlN layer 603, and a Ni / Au electrode is formed on the entire back surface of the SiC substrate 605.

図6(B)に、n型SiC基板とn型AlNの間に、n型AlN/ Al1-x2-y2Gax2Iny2N超格子を挿入した横型素子の構造を示す。まず、MOCVD法により、n型4H-SiC(0001)基板605上に、Siドープn型AlN(膜厚3nm、Si濃度3×1019cm-3)/Al0.5Ga0.45In0.05N(膜厚3nm、Si濃度3×1019cm-3)超格子を100周期積層した超格子層604、Siドープn型AlN(膜厚0.5μm、Si濃度5×1018cm-3)層603をエピタキシャル成長させる。なお、良好なn型伝導性を得るために、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下に低減している。また、SiC基板605上には、超格子層604のうちAl組成の高いSiドープn型AlN層から先に形成する。続いて、Siドープn型AlN層603上にTi/Al/Ti/Au電極(サイズ100μm×100μm)を形成し、その電極周辺部をエッチングにより除去し、Siドープn型AlN層603のエッチングを施した面上にTi/Al/Ti/Au電極を形成する。 FIG. 6B shows the structure of a lateral element in which an n-type AlN / Al 1-x2-y2 Ga x2 In y2 N superlattice is inserted between an n-type SiC substrate and n-type AlN. First, by MOCVD, on an n-type 4H-SiC (0001) substrate 605, Si-doped n-type AlN (film thickness 3 nm, Si concentration 3 × 10 19 cm −3 ) / Al 0.5 Ga 0.45 In 0.05 N (film thickness 3 nm, Si concentration 3 × 10 19 cm −3 ) Superlattice layer 604 in which 100 superlattices are stacked, and Si-doped n-type AlN (film thickness 0.5 μm, Si concentration 5 × 10 18 cm −3 ) layer 603 are epitaxially grown . In order to obtain good n-type conductivity, the residual oxygen concentration in the group III nitride semiconductor layer is reduced to 5 × 10 16 cm −3 or less. On the SiC substrate 605, the Si-doped n-type AlN layer having a high Al composition in the superlattice layer 604 is formed first. Subsequently, a Ti / Al / Ti / Au electrode (size 100 μm × 100 μm) is formed on the Si-doped n-type AlN layer 603, the periphery of the electrode is removed by etching, and the Si-doped n-type AlN layer 603 is etched. Ti / Al / Ti / Au electrodes are formed on the applied surface.

図6(C)に、超格子を挿入していない場合のn型SiC基板上にn型AlNを積層した縦型素子の構造を示す。まず、MOCVD法により、n型4H-SiC(0001)基板605上に、直接、Siドープn型AlN(膜厚0.5μm、Si濃度5×1018cm-3)層603をエピタキシャル成長させた。なお、良好なn型伝導性を得るために、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下に低減している。続いて、Siドープn型AlN層603上にTi/Al/Ti/Au電極(サイズ100μm×100μm)を形成し、SiC基板605裏面全面にNi/Au電極を形成する。 FIG. 6C shows the structure of a vertical element in which n-type AlN is stacked on an n-type SiC substrate when no superlattice is inserted. First, an Si-doped n-type AlN (film thickness 0.5 μm, Si concentration 5 × 10 18 cm −3 ) layer 603 was epitaxially grown directly on an n-type 4H—SiC (0001) substrate 605 by MOCVD. In order to obtain good n-type conductivity, the residual oxygen concentration in the group III nitride semiconductor layer is reduced to 5 × 10 16 cm −3 or less. Subsequently, a Ti / Al / Ti / Au electrode (size 100 μm × 100 μm) is formed on the Si-doped n-type AlN layer 603, and a Ni / Au electrode is formed on the entire back surface of the SiC substrate 605.

図6(A)、(B)、(C)に示す構造を有する各素子の電流−電圧特性について述べる。図6(A)の超格子を挿入した縦型構造の場合、良好なオーミック特性を有する縦方向の電気伝導性が得られる。また、素子抵抗も2.5Ωと低い。しかし、図6(B)の超格子を挿入した横型構造の場合、オーミック特性は得られたが、素子抵抗は250Ωと高くなる。また、図6(C)の超格子を挿入していない縦型素子の場合、SiC基板/Siドープn型AlN界面の大きなバンドオフセットに起因して、電流−電圧特性は強い整流性を示し、良好なオーミック性は得られない。   The current-voltage characteristics of each element having the structure shown in FIGS. 6A, 6B, and 6C will be described. In the case of the vertical structure in which the superlattice shown in FIG. 6A is inserted, vertical electrical conductivity having good ohmic characteristics can be obtained. In addition, the element resistance is as low as 2.5Ω. However, in the case of the lateral structure in which the superlattice shown in FIG. 6B is inserted, ohmic characteristics are obtained, but the element resistance is as high as 250Ω. In addition, in the case of the vertical element in which the superlattice of FIG. 6 (C) is not inserted, the current-voltage characteristic shows strong rectification due to a large band offset of the SiC substrate / Si-doped n-type AlN interface, Good ohmic properties cannot be obtained.

次に、素子構造図6(A)と同様な構造において、n型AlN/ Al1-x2-y2Gax2Iny2N超格子の組成と電気伝導特性の関係について述べる。Ga組成x2が0.2≦x2≦0.9の範囲、In組成y2が0≦y2≦0.1の範囲においてのみ、良好なオーミック性を有する縦方向の電気伝導性が得られる。Ga組成x2が0.2>x2の範囲においては、超格子のバンドギャップが大きくなり、SiCから効率良く電子が注入されないために、電気伝導性が悪くなる。一方、Ga組成x2がx2>0.9の範囲においては、AlNとAl1-x2-y2Gax2Iny2Nの格子不整が大きくなり、結晶性が劣化し、電気伝導性が悪くなる。また、In組成y2がy2>0.1の範囲においては、Al1-x2-y2Gax2Iny2Nの結晶性が劣化し、電気伝導性が悪くなる。 Next, the relationship between the composition of the n-type AlN / Al 1 -x 2 -y 2 Ga x 2 In y 2 N superlattice and the electrical conduction characteristics in the same structure as that shown in FIG. 6A will be described. Only in the range where the Ga composition x2 is in the range of 0.2 ≦ x2 ≦ 0.9 and the In composition y2 is in the range of 0 ≦ y2 ≦ 0.1, the longitudinal electrical conductivity having good ohmic properties can be obtained. When the Ga composition x2 is in the range of 0.2> x2, the band gap of the superlattice becomes large, and electrons are not efficiently injected from SiC, resulting in poor electrical conductivity. On the other hand, in the range of Ga composition x2 is x2> 0.9, the lattice mismatch of AlN and Al 1-x2-y2 Ga x2 In y2 N is increased, the crystallinity is deteriorated, the electrical conductivity is deteriorated. Further, when the In composition y2 is in the range of y2> 0.1, the crystallinity of Al 1-x2-y2 Ga x2 In y2 N deteriorates and the electrical conductivity deteriorates.

このようにして本実施形態は、n型SiC基板上に縦方向の高い電気伝導性を有するAlN縦型半導体素子を実現できる。   In this manner, this embodiment can realize an AlN vertical semiconductor element having high electrical conductivity in the vertical direction on an n-type SiC substrate.

(実施形態4)
・p型AlGaInN
本実施形態に係るp型SiC基板とp型III族窒化物半導体(Al1-x-yGaxInyN)の間に、p型Al1-x1-y1Gax1Iny1N/Al1-x2-y2Gax2Iny2N超格子を挿入したことを特徴とする縦型素子の構造と電気伝導特性について、図面を参照しながら詳しく説明する。また、比較のため、図7(B)、(C)に示す構造を有する素子の電気伝導性も評価した。まず、各素子の構造とその作製方法について説明する。
(Embodiment 4)
・ P-type AlGaInN
P-type Al 1-x1-y1 Ga x1 In y1 N / Al 1-x2 between the p-type SiC substrate and the p-type group III nitride semiconductor (Al 1-xy Ga x In y N) according to this embodiment The structure and electrical conduction characteristics of a vertical element characterized by inserting a -y2 Ga x2 In y2 N superlattice will be described in detail with reference to the drawings. For comparison, the electrical conductivity of the element having the structure shown in FIGS. 7B and 7C was also evaluated. First, the structure of each element and the manufacturing method thereof will be described.

図7(A)に、p型SiC基板とp型III族窒化物半導体(Al1-x-yGaxInyN)の間に、p型Al1-x1-y1Gax1Iny1N/Al1-x2-y2Gax2Iny2N超格子を挿入した縦型素子の構造を示す。まず、MOCVD法により、p型6H-SiC(0001)基板706上に、Mgドープp型Al0.75Ga0.2In0.05N (膜厚3nm、Mg濃度5×1019cm-3)/Al0.2Ga0.75In0.05N(膜厚3nm、Mg濃度5×1019cm-3)超格子を100周期積層した超格子層705、Mgドープp型Al0.45Ga0.5In0.1N (膜厚0.5μm、Mg濃度5×1019cm-3)層704をエピタキシャル成長させた。なお、良好なp型伝導性を得るために、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下に低減している。また、SiC基板706上には、超格子層705のうちAl組成の高いMgドープp型Al0.75Ga0.2In0.05N層から先に形成する。続いて、Mgドープp型Al0.45Ga0.5In0.1N層704上にPd/Au電極701(サイズ100μm×100μm)を形成し、SiC基板706裏面全面にNi/Au電極702を形成する。 FIG. 7A shows a p-type Al 1-x1-y1 Ga x1 In y1 N / Al 1 between a p-type SiC substrate and a p-type group III nitride semiconductor (Al 1-xy Ga x In y N). The structure of a vertical element in which a -x2-y2 Ga x2 In y2 N superlattice is inserted is shown. First, Mg-doped p-type Al 0.75 Ga 0.2 In 0.05 N (film thickness 3 nm, Mg concentration 5 × 10 19 cm −3 ) / Al 0.2 Ga 0.75 is formed on a p-type 6H—SiC (0001) substrate 706 by MOCVD. In 0.05 N (film thickness 3 nm, Mg concentration 5 × 10 19 cm −3 ) superlattice layer 705 in which 100 superlattices are laminated, Mg-doped p-type Al 0.45 Ga 0.5 In 0.1 N (film thickness 0.5 μm, Mg concentration 5 × 10 19 cm −3 ) layer 704 was epitaxially grown. In order to obtain good p-type conductivity, the residual oxygen concentration in the group III nitride semiconductor layer is reduced to 5 × 10 16 cm −3 or less. On the SiC substrate 706, the Mg-doped p-type Al 0.75 Ga 0.2 In 0.05 N layer having a high Al composition in the superlattice layer 705 is formed first. Subsequently, a Pd / Au electrode 701 (size 100 μm × 100 μm) is formed on the Mg-doped p-type Al 0.45 Ga 0.5 In 0.1 N layer 704, and a Ni / Au electrode 702 is formed on the entire back surface of the SiC substrate 706.

図7(B)に、p型SiC基板とp型III族窒化物半導体(Al1-x-yGaxInyN)の間に、p型Al1-x1-y1Gax1Iny1N/Al1-x2-y2Gax2Iny2N超格子を挿入した横型素子の構造を示す。まず、MOCVD法により、p型6H-SiC(0001)基板706上に、Mgドープp型Al0.75Ga0.2In0.05N (膜厚3nm、Mg濃度5×1019cm-3) /Al0.2Ga0.75In0.05N (膜厚3nm、Mg濃度5×1019cm-3)超格子を100周期積層した超格子層705、Mgドープp型Al0.45Ga0.5In0.1N (膜厚0.5μm、Mg濃度5×1019cm-3)層704をエピタキシャル成長させる。なお、良好なp型伝導性を得るために、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下に低減している。また、SiC基板706上には、超格子層705のうちAl組成の高いMgドープp型Al0.75Ga0.2In0.05N層から先に形成する。続いて、Mgドープp型Al0.45Ga0.5In0.1N層704上にPd/Au電極703(サイズ100μm×100μm)を形成し、その電極周辺部をエッチングにより除去し、Mgドープp型Al0.45Ga0.5In0.1N層のエッチングを施した面上にPd/Au電極702を形成する。 FIG. 7B shows a p-type Al 1-x1-y1 Ga x1 In y1 N / Al 1 between the p-type SiC substrate and the p-type group III nitride semiconductor (Al 1-xy Ga x In y N). This shows the structure of a lateral element in which a -x2-y2 Ga x2 In y2 N superlattice is inserted. First, Mg-doped p-type Al 0.75 Ga 0.2 In 0.05 N (film thickness 3 nm, Mg concentration 5 × 10 19 cm −3 ) / Al 0.2 Ga 0.75 is formed on a p-type 6H—SiC (0001) substrate 706 by MOCVD. In 0.05 N (film thickness 3 nm, Mg concentration 5 × 10 19 cm −3 ) Superlattice layer 705 in which 100 superlattices are laminated, Mg-doped p-type Al 0.45 Ga 0.5 In 0.1 N (film thickness 0.5 μm, Mg concentration 5 X10 19 cm -3 ) layer 704 is grown epitaxially. In order to obtain good p-type conductivity, the residual oxygen concentration in the group III nitride semiconductor layer is reduced to 5 × 10 16 cm −3 or less. On the SiC substrate 706, the Mg-doped p-type Al 0.75 Ga 0.2 In 0.05 N layer having a high Al composition in the superlattice layer 705 is formed first. Subsequently, a Pd / Au electrode 703 (size 100 μm × 100 μm) is formed on the Mg-doped p-type Al 0.45 Ga 0.5 In 0.1 N layer 704, the periphery of the electrode is removed by etching, and Mg-doped p-type Al 0.45 Ga. A Pd / Au electrode 702 is formed on the etched surface of the 0.5 In 0.1 N layer.

図7(C)に、超格子を挿入していない場合のp型SiC基板上にp型III族窒化物半導体(Al1-x-yGaxInyN)を積層した縦型素子の構造を示す。まず、MOCVD法により、p型6H-SiC(0001)基板706上に、直接、Mgドープp型Al0.45Ga0.5In0.1N (膜厚0.5μm、Mg濃度5×1019cm-3)層704をエピタキシャル成長させる。なお、良好なp型伝導性を得るために、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下に低減している。続いて、Mgドープp型Al0.45Ga0.5In0.1N層704上にPd/Au電極701(サイズ100μm×100μm)を形成し、SiC基板706裏面にNi/Au電極702を形成する。 FIG. 7C shows the structure of a vertical element in which a p-type group III nitride semiconductor (Al 1-xy Ga x In y N) is stacked on a p-type SiC substrate when no superlattice is inserted. . First, an Mg-doped p-type Al 0.45 Ga 0.5 In 0.1 N (film thickness 0.5 μm, Mg concentration 5 × 10 19 cm −3 ) layer 704 is directly formed on a p-type 6H—SiC (0001) substrate 706 by MOCVD. Is epitaxially grown. In order to obtain good p-type conductivity, the residual oxygen concentration in the group III nitride semiconductor layer is reduced to 5 × 10 16 cm −3 or less. Subsequently, a Pd / Au electrode 701 (size 100 μm × 100 μm) is formed on the Mg-doped p-type Al 0.45 Ga 0.5 In 0.1 N layer 704, and a Ni / Au electrode 702 is formed on the back surface of the SiC substrate 706.

図7(A)、(B)、(C)に示す構造を有する各素子の電流−電圧特性について述べる。図7(A)の超格子を挿入した縦型構造の場合、良好なオーミック特性を有する縦方向の電気伝導性が得られる。また、素子抵抗も5Ωと低い。しかし、図7(B)の超格子を挿入した横型構造の場合、オーミック特性は得られるが、素子抵抗は2500Ωと高くなる。また、図7(C)の超格子を挿入していない縦型素子の場合、p型SiC基板/Mgドープp型Al1-x3-y3Gax3Iny3N界面のバンドオフセットに起因して、電流−電圧特性は強い整流性を示し、良好なオーミック性は得られない。以上のように、超格子を挿入することでSiC基板の縦型素子においても電流−電圧特性がオーミック性になり、また、素子抵抗を低減できる。 The current-voltage characteristics of each element having the structure shown in FIGS. 7A, 7B, and 7C will be described. In the case of the vertical structure in which the superlattice shown in FIG. 7A is inserted, vertical electrical conductivity having good ohmic characteristics can be obtained. In addition, the element resistance is as low as 5Ω. However, in the case of the lateral structure in which the superlattice shown in FIG. 7B is inserted, ohmic characteristics can be obtained, but the element resistance is as high as 2500Ω. In addition, in the case of the vertical element in which the superlattice of FIG. 7C is not inserted, due to the band offset of the p-type SiC substrate / Mg-doped p-type Al 1-x3-y3 Ga x3 In y3 N interface, The current-voltage characteristic shows strong rectification, and good ohmic characteristics cannot be obtained. As described above, by inserting the superlattice, the current-voltage characteristic becomes ohmic even in the vertical element of the SiC substrate, and the element resistance can be reduced.

また、実施形態1と同様に、p型SiC基板とp型III族窒化物半導体(Al1-x-yGaxInyN)の間にp型Al1-x1-y1Gax1Iny1N/Al1-x2-y2Gax2Iny2N超格子を挿入する際、x≧x1かつy≧y1もしくはx≧x2かつy≧y2とすることで、p型III族窒化物半導体の膜厚10μm程度まで厚くしてもクラックは発生しない。 Similarly to the first embodiment, the p-type Al 1-x1-y1 Ga x1 In y1 N / Al is interposed between the p-type SiC substrate and the p-type group III nitride semiconductor (Al 1-xy Ga x In y N). When inserting a 1-x2-y2 Ga x2 In y2 N superlattice, x ≧ x1 and y ≧ y1 or x ≧ x2 and y ≧ y2 up to a p-type group III nitride semiconductor film thickness of about 10 μm Cracks do not occur even when the thickness is increased.

このようにして本実施形態は、p型SiC基板上に縦方向の高い電気伝導性を有する高Al組成AlGaInN縦型半導体素子を実現できる。   In this manner, this embodiment can realize a high Al composition AlGaInN vertical semiconductor element having high electrical conductivity in the vertical direction on a p-type SiC substrate.

(実施例5)
・p型AlN
本実施形態に係るp型SiC基板とp型AlNの間に、p型AlN/ Al1-x2-y2Gax2Iny2N超格子を挿入したことを特徴とする縦型素子の構造と電気伝導特性について、図面を参照しながら詳しく説明する。まず、各素子の構造とその作製方法について説明する。また、比較のため、図8(B)、(C)に示す構造を有する素子の電気伝導性も評価した。まず、各素子の構造とその作製方法について説明する。
(Example 5)
・ P-type AlN
Structure and electrical conduction of a vertical element characterized by inserting a p-type AlN / Al 1-x2-y2 Ga x2 In y2 N superlattice between the p-type SiC substrate and the p-type AlN according to the present embodiment The characteristics will be described in detail with reference to the drawings. First, the structure of each element and the manufacturing method thereof will be described. For comparison, the electrical conductivity of the element having the structure shown in FIGS. 8B and 8C was also evaluated. First, the structure of each element and the manufacturing method thereof will be described.

図8(A)に、p型SiC基板とp型AlNの間に、p型AlN/ Al1-x2-y2Gax2Iny2N超格子を挿入した縦型素子の構造を示す。まず、MOCVD法により、p型6H-SiC(0001)基板806上に、Mgドープp型AlN(膜厚3nm、Mg濃度5×1019cm-3)/Al0.6Ga0.3In0.1N(膜厚3nm、Mg濃度5×1019cm-3)超格子を100周期積層した超格子層805、Mgドープp型AlN (膜厚0.5μm、Mg濃度5×1019cm-3) 層804をエピタキシャル成長させる。なお、良好なp型伝導性を得るために、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下に低減している。また、SiC基板806上には、超格子層805のうちAl組成の高いMgドープp型AlN層から先に形成する。続いて、Mgドープp型AlN層804上にPd/Au電極801(サイズ100μm×100μm)を形成し、p型SiC基板806裏面全面にNi/Au電極802を形成する。 FIG. 8A shows the structure of a vertical element in which a p-type AlN / Al 1-x2-y2 Ga x2 In y2 N superlattice is inserted between a p-type SiC substrate and p-type AlN. First, Mg doped p-type AlN (film thickness: 3 nm, Mg concentration: 5 × 10 19 cm −3 ) / Al 0.6 Ga 0.3 In 0.1 N (film thickness) on a p-type 6H—SiC (0001) substrate 806 by MOCVD. 3 nm, Mg concentration 5 × 10 19 cm −3 ) Superlattice layer 805 in which 100 superlattices are stacked, and Mg-doped p-type AlN (film thickness 0.5 μm, Mg concentration 5 × 10 19 cm −3 ) layer 804 are epitaxially grown . In order to obtain good p-type conductivity, the residual oxygen concentration in the group III nitride semiconductor layer is reduced to 5 × 10 16 cm −3 or less. On the SiC substrate 806, the Mg-doped p-type AlN layer having a high Al composition in the superlattice layer 805 is formed first. Subsequently, a Pd / Au electrode 801 (size 100 μm × 100 μm) is formed on the Mg-doped p-type AlN layer 804, and a Ni / Au electrode 802 is formed on the entire back surface of the p-type SiC substrate 806.

図8(B)に、p型SiC基板とp型AlNの間に、p型AlN/ Al1-x2-y2Gax2Iny2N超格子を挿入した横型素子の構造を示す。まず、MOCVD法により、p型6H-SiC(0001)基板806上に、Mgドープp型AlN(膜厚3nm、Mg濃度5×1019cm-3)/Al0.6Ga0.3In0.1N(膜厚3nm、Mg濃度5×1019cm-3)超格子を100周期積層した超格子層805、Mgドープp型AlN(膜厚0.5μm、Mg濃度5×1019cm-3)層804をエピタキシャル成長させる。なお、良好なp型伝導性を得るために、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下に低減している。また、SiC基板806上には、超格子層805のうちAl組成の高いMgドープp型AlN層から先に形成する。続いて、Mgドープp型AlN層804上にPd/Au電極803(サイズ100μm×100μm)を形成し、その電極周辺部をエッチングにより除去し、Mgドープp型AlN層804のエッチングを施した面上にPd/Au電極802を形成する。 FIG. 8B shows the structure of a lateral element in which a p-type AlN / Al 1-x2-y2 Ga x2 In y2 N superlattice is inserted between a p-type SiC substrate and p-type AlN. First, Mg doped p-type AlN (film thickness: 3 nm, Mg concentration: 5 × 10 19 cm −3 ) / Al 0.6 Ga 0.3 In 0.1 N (film thickness) on a p-type 6H—SiC (0001) substrate 806 by MOCVD. 3 nm, Mg concentration 5 × 10 19 cm −3 ) Superlattice layer 805 in which 100 superlattices are stacked, and Mg-doped p-type AlN (film thickness 0.5 μm, Mg concentration 5 × 10 19 cm −3 ) layer 804 are epitaxially grown . In order to obtain good p-type conductivity, the residual oxygen concentration in the group III nitride semiconductor layer is reduced to 5 × 10 16 cm −3 or less. On the SiC substrate 806, the Mg-doped p-type AlN layer having a high Al composition in the superlattice layer 805 is formed first. Subsequently, a Pd / Au electrode 803 (size: 100 μm × 100 μm) is formed on the Mg-doped p-type AlN layer 804, the periphery of the electrode is removed by etching, and the Mg-doped p-type AlN layer 804 is etched. A Pd / Au electrode 802 is formed thereon.

図8(C)に、超格子を挿入していない場合のp型SiC基板上にp型AlNを積層した縦型素子の構造を示す。まず、MOCVD法により、p型6H-SiC(0001)基板806上に、直接、Mgドープp型AlN (膜厚0.5μm、Mg濃度5×1019cm-3) 層804をエピタキシャル成長させる。なお、良好なp型伝導性を得るために、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下に低減している。続いて、Mgドープp型AlN層804上にPd/Au電極803(サイズ100μm×100μm)を形成し、p型SiC基板806裏面全面にNi/Au電極802を形成する。 FIG. 8C shows the structure of a vertical element in which p-type AlN is stacked on a p-type SiC substrate when no superlattice is inserted. First, an Mg-doped p-type AlN (film thickness 0.5 μm, Mg concentration 5 × 10 19 cm −3 ) layer 804 is epitaxially grown directly on a p-type 6H—SiC (0001) substrate 806 by MOCVD. In order to obtain good p-type conductivity, the residual oxygen concentration in the group III nitride semiconductor layer is reduced to 5 × 10 16 cm −3 or less. Subsequently, a Pd / Au electrode 803 (size 100 μm × 100 μm) is formed on the Mg-doped p-type AlN layer 804, and a Ni / Au electrode 802 is formed on the entire back surface of the p-type SiC substrate 806.

図8(A)、(B)、(C)に示す構造を有する各素子の電流−電圧特性について述べる。図8(A)の超格子を挿入した縦型構造の場合、良好なオーミック特性を有する縦方向の電気伝導性が得られる。また、素子抵抗も75Ωと低い。しかし、図8(B)の超格子を挿入した横型構造の場合、オーミック特性は得られたが、素子抵抗は12500Ωと極めて高くなる。また、図8(C)の超格子を挿入していない縦型素子の場合、p型SiC基板/Mgドープp型AlN界面の大きなバンドオフセットに起因して、電流−電圧特性は強い整流性を示し、良好なオーミック性は得られない。   The current-voltage characteristics of each element having the structure shown in FIGS. 8A, 8B, and 8C will be described. In the case of the vertical structure in which the superlattice shown in FIG. 8A is inserted, vertical electric conductivity having good ohmic characteristics can be obtained. In addition, the element resistance is as low as 75Ω. However, in the case of the lateral structure in which the superlattice shown in FIG. 8B is inserted, ohmic characteristics are obtained, but the element resistance is as high as 12500Ω. In addition, in the case of the vertical element in which the superlattice of FIG. 8C is not inserted, the current-voltage characteristic has a strong rectification property due to a large band offset at the interface of the p-type SiC substrate / Mg-doped p-type AlN. As shown, good ohmic properties cannot be obtained.

次に、図8(A)の素子構造において、p型AlN/ Al1-x2-y2Gax2Iny2N超格子の組成と電気伝導特性の関係を述べる。実施形態3と同様に、Ga組成x2が0.2≦x2≦0.9の範囲、In組成y2が0≦y2≦0.1の範囲においてのみ、良好なオーミック性を有する縦方向の電気伝導性が得られる。 Next, in the device structure of FIG. 8 (A), describes the relationship between the p-type AlN / Al 1-x2-y2 Ga x2 In y2 N superlattice composition and electric conduction characteristic. Similar to the third embodiment, only in the range where the Ga composition x2 is in the range of 0.2 ≦ x2 ≦ 0.9 and the In composition y2 is in the range of 0 ≦ y2 ≦ 0.1, the longitudinal electrical conductivity having good ohmic properties can be obtained.

このように本実施形態により、p型SiC基板上に縦方向の高い電気伝導性を有するAlN縦型半導体素子構造が実現できる。   Thus, according to this embodiment, an AlN vertical semiconductor element structure having high electrical conductivity in the vertical direction can be realized on a p-type SiC substrate.

(実施形態6)
・n型、AlInGaN半導体発光素子
本実施形態に係るn型SiC基板とn型III族窒化物半導体(Al1-x-yGaxInyN)の間に、n型Al1-x1-y1Gax1Iny1N/Al1-x2-y2Gax2Iny2N超格子を挿入したことを特徴とする縦型発光ダイオードの構造について、図面を参照しながら説明する。また、比較のため、同様の半導体積層構造の横型発光ダイオードについても説明する。
(Embodiment 6)
N-type, AlInGaN semiconductor light emitting device n-type Al 1-x1-y1 Ga x1 between the n-type SiC substrate and the n-type group III nitride semiconductor (Al 1-xy Ga x In y N) according to this embodiment A structure of a vertical light emitting diode characterized by inserting an In y1 N / Al 1-x2-y2 Ga x2 In y2 N superlattice will be described with reference to the drawings. For comparison, a lateral light emitting diode having a similar semiconductor multilayer structure will also be described.

図9(A)に、n型SiC基板とn型III族窒化物半導体(Al1-x-yGaxInyN)の間に、n型Al1-x1-y1Gax1Iny1N/Al1-x2-y2Gax2Iny2N超格子を挿入した縦型発光ダイオードの構造を示す。まず、MOCVD法により、n型4H-SiC(0001)基板907上に、Siドープn型Al0.8Ga0.45In0.05N(膜厚3nm、Si濃度3×1019cm-3)/Al0.5Ga0.45In0.05N(膜厚3nm、Si濃度3×1019cm-3)超格子を100周期積層した超格子層906、Siドープn型Al0.75Ga0.2In0.05N (膜厚0.5μm、Si濃度5×1018cm-3) 層905、Al0.6Ga0.35In0.05N(膜厚5nm)発光層904、Mgドープp型Al0.75Ga0.2In0.05N (膜厚0.1μm、Mg濃度5×1019cm-3) 層903をエピタキシャル成長する。なお、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下である。また、SiC基板907上には、超格子のうちAl組成の高いSiドープn型Al0.8Ga0.15In0.05Nから先に形成する。続いて、Mgドープp型Al0.75Ga0.2In0.05N層903上にPd/Au電極901(サイズ150μm×150μm)を形成し、n型SiC基板907裏面全面にNi/Au電極902を形成する。 FIG. 9A shows an n-type Al 1-x1-y1 Ga x1 In y1 N / Al 1 between an n-type SiC substrate and an n-type Group III nitride semiconductor (Al 1-xy Ga x In y N). The structure of a vertical light-emitting diode in which a -x2-y2 Ga x2 In y2 N superlattice is inserted is shown. First, by MOCVD, on an n-type 4H—SiC (0001) substrate 907, Si-doped n-type Al 0.8 Ga 0.45 In 0.05 N (film thickness 3 nm, Si concentration 3 × 10 19 cm −3 ) / Al 0.5 Ga 0.45 In 0.05 N (film thickness 3 nm, Si concentration 3 × 10 19 cm −3 ) superlattice layer 906 in which 100 superlattices are stacked, Si-doped n-type Al 0.75 Ga 0.2 In 0.05 N (film thickness 0.5 μm, Si concentration 5 × 10 18 cm −3 ) Layer 905, Al 0.6 Ga 0.35 In 0.05 N (film thickness 5 nm), light emitting layer 904, Mg-doped p-type Al 0.75 Ga 0.2 In 0.05 N (film thickness 0.1 μm, Mg concentration 5 × 10 19 cm) -3 ) The layer 903 is epitaxially grown. The residual oxygen concentration in the group III nitride semiconductor layer is 5 × 10 16 cm −3 or less. On the SiC substrate 907, Si-doped n-type Al 0.8 Ga 0.15 In 0.05 N having a high Al composition in the superlattice is formed first. Subsequently, a Pd / Au electrode 901 (size 150 μm × 150 μm) is formed on the Mg-doped p-type Al 0.75 Ga 0.2 In 0.05 N layer 903, and a Ni / Au electrode 902 is formed on the entire back surface of the n-type SiC substrate 907.

図9(B)に、n型SiC基板とn型III族窒化物半導体(Al1-x-yGaxInyN)の間に、n型Al1-x1-y1Gax1Iny1N/Al1-x2-y2Gax2Iny2N超格子を挿入した横型発光ダイオードの構造を示す。まず、MOCVD法により、n型4H-SiC(0001)基板907上に、Siドープn型Al0.8Ga0.15In0.05N(膜厚3nm、Si濃度3×1019cm-3)/Al0.5Ga0.45In0.05N(膜厚3nm、Si濃度3×1019cm-3)超格子を100周期積層した超格子層906、Siドープn型Al0.75Ga0.2In0.05N (膜厚0.5μm、Si濃度5×1018cm-3) 層905、Al0.6Ga0.35In0.05N(膜厚5nm)発光層904、Mgドープp型Al0.75Ga0.2In0.05N (膜厚0.1μm、Mg濃度5×1019cm-3) 層903をエピタキシャル成長させる。なお、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下である。また、SiC基板907上には、超格子のうちAl組成の高いSiドープn型Al0.8Ga0.15In0.05Nから先に形成する。続いて、Mgドープp型Al0.75Ga0.2In0.05N層903上にPd/Au電極901(サイズ150μm×150μm)を形成し、その電極周辺部をエッチングにより除去し、露出したSiドープn型Al0.75Ga0.2In0.05N層905上にTi/Al/Ti/Au電極902を形成する。 FIG. 9B shows an n-type Al 1-x1-y1 Ga x1 In y1 N / Al 1 between the n-type SiC substrate and the n-type Group III nitride semiconductor (Al 1-xy Ga x In y N). The structure of a lateral light emitting diode having a -x2-y2 Ga x2 In y2 N superlattice inserted is shown. First, by MOCVD, on an n-type 4H—SiC (0001) substrate 907, Si-doped n-type Al 0.8 Ga 0.15 In 0.05 N (film thickness 3 nm, Si concentration 3 × 10 19 cm −3 ) / Al 0.5 Ga 0.45 In 0.05 N (film thickness 3 nm, Si concentration 3 × 10 19 cm −3 ) superlattice layer 906 in which 100 superlattices are stacked, Si-doped n-type Al 0.75 Ga 0.2 In 0.05 N (film thickness 0.5 μm, Si concentration 5 × 10 18 cm −3 ) Layer 905, Al 0.6 Ga 0.35 In 0.05 N (film thickness 5 nm), light emitting layer 904, Mg-doped p-type Al 0.75 Ga 0.2 In 0.05 N (film thickness 0.1 μm, Mg concentration 5 × 10 19 cm) -3 ) The layer 903 is epitaxially grown. The residual oxygen concentration in the group III nitride semiconductor layer is 5 × 10 16 cm −3 or less. On the SiC substrate 907, Si-doped n-type Al 0.8 Ga 0.15 In 0.05 N having a high Al composition in the superlattice is formed first. Subsequently, a Pd / Au electrode 901 (size 150 μm × 150 μm) is formed on the Mg-doped p-type Al 0.75 Ga 0.2 In 0.05 N layer 903, the periphery of the electrode is removed by etching, and the exposed Si-doped n-type Al A Ti / Al / Ti / Au electrode 902 is formed on the 0.75 Ga 0.2 In 0.05 N layer 905.

図10に、作製した素子の直流駆動時における電流−電圧特性を示す。これは測定した結果である。図9(A)の本実施形態に係る縦型発光ダイオードにおいて、良好な縦方向の電気伝導性が得られる。また、素子抵抗も5Ωと低く、1000mA程度の高電流条件下でも直流駆動で安定に動作する。一方、図9(B)の従来の横型発光ダイオードの順方向の素子抵抗は80Ωと高く、電流を300mA以上に増加すると、素子が動作中に破壊するなど、安定な動作が得られない場合がある。   FIG. 10 shows current-voltage characteristics of the fabricated element during DC driving. This is a measurement result. In the vertical light emitting diode according to this embodiment shown in FIG. 9A, good vertical electrical conductivity can be obtained. In addition, the device resistance is as low as 5Ω, and it operates stably with DC drive even under high current conditions of about 1000mA. On the other hand, the device resistance in the forward direction of the conventional horizontal light emitting diode of FIG. 9B is as high as 80Ω, and if the current is increased to 300 mA or more, the device may be destroyed during operation and stable operation may not be obtained. is there.

図11に、直流駆動条件での発光出力の駆動電流依存性を示す。本素子の発光波長は250nmである。尚、Al1-x4-y4Gax4Iny4N発光層のGa組成x4を0≦x4≦0.6とし、In組成y4を0≦y4≦0.1とすることで、発光波長を約200nmから300nmの遠紫外域に調整できる。図11(A)の本発明による縦型発光ダイオードにおいては、1000mA程度まで発光出力はほぼ線形的に増加する。しかし、図11(B)の従来の横型発光ダイオードにおいては、発熱のため、300mA程度で発光出力は飽和する。 FIG. 11 shows the drive current dependence of the light emission output under the DC drive conditions. The emission wavelength of this element is 250 nm. Incidentally, the Ga composition x4 of the Al 1-x4-y4 Ga x4 In y4 N light emitting layer is set to 0 ≦ x4 ≦ 0.6, and the In composition y4 is set to 0 ≦ y4 ≦ 0.1, so that the emission wavelength is about 200 nm to 300 nm. It can be adjusted to the ultraviolet region. In the vertical light emitting diode according to the present invention shown in FIG. 11A, the light emission output increases almost linearly up to about 1000 mA. However, in the conventional lateral light emitting diode of FIG. 11B, the light emission output is saturated at about 300 mA due to heat generation.

このように本実施形態は、n型SiC基板上に高Al組成AlGaInNを用いた縦型遠紫外発光ダイオードを実現できる。   Thus, this embodiment can realize a vertical far ultraviolet light emitting diode using a high Al composition AlGaInN on an n-type SiC substrate.

(実施形態7)
・n型、AlN半導体発光素子
本実施形態に係るn型SiC基板とn型AlNの間に、n型AlN/Al1-x2-y2Gax2Iny2N超格子を挿入したことを特徴とする縦型発光ダイオードの構造について、図面を参照しながら説明する。また、比較のため、同様の半導体積層構造の横型発光ダイオードについても述べる。
(Embodiment 7)
-N-type, AlN semiconductor light-emitting device An n-type AlN / Al 1-x2-y2 Ga x2 In y2 N superlattice is inserted between the n-type SiC substrate and the n-type AlN according to this embodiment. The structure of the vertical light emitting diode will be described with reference to the drawings. For comparison, a horizontal light emitting diode having a similar semiconductor stacked structure is also described.

図12(A)に、n型SiC基板とn型AlNの間に、n型AlN/Al1-x2-y2Gax2Iny2N超格子を挿入した縦型発光ダイオードの構造を示す。まず、MOCVD法により、n型4H-SiC(0001)基板1207上に、Siドープn型AlN(膜厚3nm、Si濃度3×1019cm-3) /Al0.5Ga0.45In0.05N(膜厚3nm、Si濃度3×1019cm-3)超格子を100周期積層した超格子層1206、Siドープn型AlN (膜厚0.5μm、Si濃度5×1018cm-3) 層1205、AlN(膜厚50nm)発光層1204、Mgドープp型AlN (膜厚0.1μm、Mg濃度5×1019cm-3) 層1203をエピタキシャル成長させる。なお、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下である。また、SiC基板1207上には、超格子層1206のうちAl組成の高いSiドープn型AlNから先に形成する。続いて、Mgドープp型AlN層1203上にPd/Au電極1201(サイズ150μm×150μm)を形成し、n型SiC基板1207裏面全面にNi/Au電極1202を形成する。 FIG. 12A shows the structure of a vertical light emitting diode in which an n-type AlN / Al 1-x2-y2 Ga x2 In y2 N superlattice is inserted between an n-type SiC substrate and n-type AlN. First, by MOCVD, on an n-type 4H-SiC (0001) substrate 1207, Si-doped n-type AlN (film thickness 3 nm, Si concentration 3 × 10 19 cm −3 ) / Al 0.5 Ga 0.45 In 0.05 N (film thickness 3 nm, Si concentration 3 × 10 19 cm −3 ) Superlattice layer 1206 in which 100 superlattices are stacked, Si-doped n-type AlN (film thickness 0.5 μm, Si concentration 5 × 10 18 cm −3 ) layer 1205, AlN ( A light emitting layer 1204 having a thickness of 50 nm) and an Mg-doped p-type AlN (thickness 0.1 μm, Mg concentration 5 × 10 19 cm −3 ) layer 1203 are epitaxially grown. The residual oxygen concentration in the group III nitride semiconductor layer is 5 × 10 16 cm −3 or less. Further, on the SiC substrate 1207, the Si-doped n-type AlN having a high Al composition in the superlattice layer 1206 is formed first. Subsequently, a Pd / Au electrode 1201 (size 150 μm × 150 μm) is formed on the Mg-doped p-type AlN layer 1203, and a Ni / Au electrode 1202 is formed on the entire back surface of the n-type SiC substrate 1207.

図12(B)に、n型SiC基板とn型AlNの間に、n型AlN/Al1-x2-y2Gax2Iny2N超格子を挿入した横型発光ダイオードの構造を示す。まず、MOCVD法により、n型4H-SiC(0001)基板1207上に、Siドープn型AlN(膜厚3nm、Si濃度3×1019cm-3)/Al0.5Ga0.45In0.05N(膜厚3nm、Si濃度3×1019cm-3)超格子を100周期積層した超格子層1206、Siドープn型AlN (膜厚0.5μm、Si濃度5×1018cm-3) 層1205、AlN(膜厚50nm)発光層1204、Mgドープp型AlN (膜厚0.1μm、Mg濃度5×1019cm-3) 層1203をエピタキシャル成長させる。なお、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下である。また、SiC基板1207上には、超格子層1206のうちAl組成の高いSiドープn型AlNから先に形成する。続いて、Mgドープp型AlN層1203上にPd/Au電極1201(サイズ150μm×150μm)を形成し、その電極周辺部をエッチングにより除去し、露出したSiドープn型AlN層1205上にTi/Al/Ti/Au電極1202を形成する。 FIG. 12B shows the structure of a lateral light emitting diode in which an n-type AlN / Al 1-x2-y2 Ga x2 In y2 N superlattice is inserted between an n-type SiC substrate and n-type AlN. First, by MOCVD, on an n-type 4H—SiC (0001) substrate 1207, Si-doped n-type AlN (film thickness 3 nm, Si concentration 3 × 10 19 cm −3 ) / Al 0.5 Ga 0.45 In 0.05 N (film thickness 3 nm, Si concentration 3 × 10 19 cm −3 ) Superlattice layer 1206 in which 100 superlattices are stacked, Si-doped n-type AlN (film thickness 0.5 μm, Si concentration 5 × 10 18 cm −3 ) layer 1205, AlN ( A light emitting layer 1204 having a thickness of 50 nm) and an Mg-doped p-type AlN (thickness 0.1 μm, Mg concentration 5 × 10 19 cm −3 ) layer 1203 are epitaxially grown. The residual oxygen concentration in the group III nitride semiconductor layer is 5 × 10 16 cm −3 or less. Further, on the SiC substrate 1207, the Si-doped n-type AlN having a high Al composition in the superlattice layer 1206 is formed first. Subsequently, a Pd / Au electrode 1201 (size 150 μm × 150 μm) is formed on the Mg-doped p-type AlN layer 1203, the periphery of the electrode is removed by etching, and the Ti / N-type AlN layer 1205 is exposed on the Ti / N-type AlN layer 1205. An Al / Ti / Au electrode 1202 is formed.

作製した素子の直流駆動時における電流−電圧特性について述べる。図12(A)の本発明による縦型発光ダイオードにおいて、縦方向の電気伝導性が得られる。また、素子抵抗も8Ωと低く、1000mA程度の高電流条件下でも直流駆動で安定に動作する。一方、図12(B)の従来の横型発光ダイオードの順方向の素子抵抗は160Ωと高く、電流を300mA以上に増加すると、素子が動作中に破壊するなど、安定な動作が得られない場合がある。   The current-voltage characteristics at the time of direct current driving of the manufactured element will be described. In the vertical light emitting diode according to the present invention shown in FIG. 12A, electrical conductivity in the vertical direction can be obtained. In addition, the element resistance is as low as 8Ω, and it operates stably with DC drive even under high current conditions of about 1000mA. On the other hand, the device resistance in the forward direction of the conventional lateral light emitting diode of FIG. 12B is as high as 160Ω, and if the current is increased to 300 mA or more, the device may be destroyed during operation and stable operation may not be obtained. is there.

発光出力の直流駆動時における駆動電流依存性について述べる。本素子の発光波長は210nmである。尚、Al1-x4-y4Gax4Iny4N発光層のGa組成x4を0≦x4≦0.6とし、In組成y4を0≦y4≦0.1とすることで、発光波長を約200nmから300nmの遠紫外域に調整できる。図12(A)の本発明による縦型発光ダイオードにおいては、1000mA程度まで発光出力はほぼ線形的に増加する。しかし、図12(B)の従来の横型発光ダイオードにおいては、発熱のため、300mA程度で発光出力は飽和した。 The drive current dependency of the light emission output during DC driving will be described. The emission wavelength of this element is 210 nm. Incidentally, the Ga composition x4 of the Al 1-x4-y4 Ga x4 In y4 N light emitting layer is set to 0 ≦ x4 ≦ 0.6, and the In composition y4 is set to 0 ≦ y4 ≦ 0.1, so that the emission wavelength is about 200 nm to 300 nm. It can be adjusted to the ultraviolet region. In the vertical light emitting diode of the present invention shown in FIG. 12A, the light emission output increases almost linearly up to about 1000 mA. However, in the conventional lateral light emitting diode of FIG. 12B, the light emission output was saturated at about 300 mA due to heat generation.

このようにして本実施形態は、n型SiC基板上にAlNを用いた縦型遠紫外発光ダイオードを実現する。   Thus, the present embodiment realizes a vertical far ultraviolet light emitting diode using AlN on an n-type SiC substrate.

(実施形態8)
・p型、AlInGaN半導体発光素子
本実施形態に係るp型SiC基板とp型III族窒化物半導体(Al1-x-yGaxInyN)の間に、p型Al1-x1-y1Gax1Iny1N/Al1-x2-y2Gax2Iny2N超格子を挿入したことを特徴とする縦型発光ダイオードの構造について、図面を参照しながら説明する。また、比較のため、同様の半導体積層構造の横型発光ダイオードについても述べる。
(Embodiment 8)
P-type, AlInGaN semiconductor light emitting device p-type Al 1-x1-y1 Ga x1 between the p-type SiC substrate and p-type group III nitride semiconductor (Al 1-xy Ga x In y N) according to the present embodiment A structure of a vertical light emitting diode characterized by inserting an In y1 N / Al 1-x2-y2 Ga x2 In y2 N superlattice will be described with reference to the drawings. For comparison, a horizontal light emitting diode having a similar semiconductor stacked structure is also described.

図13(A)に、p型SiC基板とp型III族窒化物半導体(Al1-x-yGaxInyN)の間に、p型Al1-x1-y1Gax1Iny1N/Al1-x2-y2Gax2Iny2N超格子を挿入した縦型発光ダイオードの構造を示す。まず、MOCVD法により、p型6H-SiC(0001)基板1307上に、Mgドープp型Al0.8Ga0.15In0.05N(膜厚3nm、Mg濃度5×1019cm-3)/Al0.5Ga0.45In0.05N(膜厚3nm、Mg濃度5×1019cm-3)超格子を100周期積層した超格子層1306、Mgドープp型Al0.75Ga0.2In0.05N (膜厚0.5μm、Mg濃度5×1019cm-3) 層1305、Al0.7Ga0.2In0.05N(膜厚5nm)発光層1304、Siドープn型Al0.75Ga0.2In0.05N (膜厚0.1μm、Si濃度3×1019cm-3) 層1303をエピタキシャル成長させる。なお、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下である。また、SiC基板1307上には、超格子層1306のうちAl組成の高いMgドープp型Al0.8Ga0.15In0.05Nから先に形成する。続いて、Siドープn型Al0.75Ga0.2In0.05N層1303上にTi/Al/Ti/Au電極1301(サイズ150μm×150μm)を形成し、p型SiC基板1307裏面全面にNi/Au電極1302を形成する。 FIG. 13A shows a p-type Al 1-x1-y1 Ga x1 In y1 N / Al 1 between a p-type SiC substrate and a p-type group III nitride semiconductor (Al 1-xy Ga x In y N). The structure of a vertical light-emitting diode in which a -x2-y2 Ga x2 In y2 N superlattice is inserted is shown. First, Mg doped p-type Al 0.8 Ga 0.15 In 0.05 N (film thickness 3 nm, Mg concentration 5 × 10 19 cm −3 ) / Al 0.5 Ga 0.45 on a p-type 6H—SiC (0001) substrate 1307 by MOCVD. In 0.05 N (thickness 3 nm, Mg concentration 5 × 10 19 cm -3 ) superlattice layer 1306 with 100 superlattice layers, Mg-doped p-type Al 0.75 Ga 0.2 In 0.05 N (thickness 0.5 μm, Mg concentration 5 × 10 19 cm −3 ) Layer 1305, Al 0.7 Ga 0.2 In 0.05 N (film thickness 5 nm), light emitting layer 1304, Si-doped n-type Al 0.75 Ga 0.2 In 0.05 N (film thickness 0.1 μm, Si concentration 3 × 10 19 cm) -3 ) The layer 1303 is epitaxially grown. The residual oxygen concentration in the group III nitride semiconductor layer is 5 × 10 16 cm −3 or less. On the SiC substrate 1307, Mg-doped p-type Al 0.8 Ga 0.15 In 0.05 N having a high Al composition in the superlattice layer 1306 is formed first. Subsequently, a Ti / Al / Ti / Au electrode 1301 (size 150 μm × 150 μm) is formed on the Si-doped n-type Al 0.75 Ga 0.2 In 0.05 N layer 1303, and a Ni / Au electrode 1302 is formed on the entire back surface of the p-type SiC substrate 1307. Form.

図13(B)に、p型SiC基板とp型III族窒化物半導体(Al1-x-yGaxInyN)の間に、p型Al1-x1-y1Gax1Iny1N/Al1-x2-y2Gax2Iny2N超格子を挿入した横型発光ダイオードの構造を示す。まず、MOCVD法により、p型6H-SiC(0001)基板1307上に、Mgドープp型Al0.8Ga0.15In0.05N(膜厚3nm、Mg濃度5×1019cm-3)/Al0.5Ga0.45In0.05N(膜厚3nm、Mg濃度5×1019cm-3)超格子を100周期積層した超格子層1306、Mgドープp型Al0.75Ga0.2In0.05N (膜厚0.5μm、Mg濃度5×1019cm-3) 層1305、Al0.7Ga0.2In0.05N(膜厚5nm)発光層1304、Siドープn型Al0.75Ga0.2In0.05N (膜厚0.1μm、Si濃度3×1019cm-3) 層1303をエピタキシャル成長させる。なお、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下である。また、SiC基板1307上には、超格子のうちAl組成の高いMgドープp型Al0.8Ga0.15In0.05Nから先に形成する。続いて、Mgドープp型Al0.75Ga0.2In0.05N層1303上にPd/Au電極1301(サイズ150μm×150μm)を形成し、その電極周辺部をエッチングにより除去し、露出したSiドープn型Al0.75Ga0.2In0.05N層1305上にTi/Al/Ti/Au電極1302を形成する。 FIG. 13B shows a p-type Al 1-x1-y1 Ga x1 In y1 N / Al 1 between the p-type SiC substrate and the p-type group III nitride semiconductor (Al 1-xy Ga x In y N). The structure of a lateral light emitting diode having a -x2-y2 Ga x2 In y2 N superlattice inserted is shown. First, Mg doped p-type Al 0.8 Ga 0.15 In 0.05 N (film thickness 3 nm, Mg concentration 5 × 10 19 cm −3 ) / Al 0.5 Ga 0.45 on a p-type 6H—SiC (0001) substrate 1307 by MOCVD. In 0.05 N (thickness 3 nm, Mg concentration 5 × 10 19 cm -3 ) superlattice layer 1306 with 100 superlattice layers, Mg-doped p-type Al 0.75 Ga 0.2 In 0.05 N (thickness 0.5 μm, Mg concentration 5 × 10 19 cm −3 ) Layer 1305, Al 0.7 Ga 0.2 In 0.05 N (film thickness 5 nm), light emitting layer 1304, Si-doped n-type Al 0.75 Ga 0.2 In 0.05 N (film thickness 0.1 μm, Si concentration 3 × 10 19 cm) -3 ) The layer 1303 is epitaxially grown. The residual oxygen concentration in the group III nitride semiconductor layer is 5 × 10 16 cm −3 or less. On the SiC substrate 1307, Mg-doped p-type Al 0.8 Ga 0.15 In 0.05 N having a high Al composition in the superlattice is formed first. Subsequently, a Pd / Au electrode 1301 (size 150 μm × 150 μm) is formed on the Mg-doped p-type Al 0.75 Ga 0.2 In 0.05 N layer 1303, and the periphery of the electrode is removed by etching, and the exposed Si-doped n-type Al A Ti / Al / Ti / Au electrode 1302 is formed on the 0.75 Ga 0.2 In 0.05 N layer 1305.

作製した素子の直流駆動時における電流―電圧特性について述べる。図13(A)の本発明による縦型発光ダイオードにおいては、縦方向の電気伝導性が得られる。また、素子抵抗も10Ωと低く、1000mA程度の高電流条件下でも直流駆動で安定に動作する。一方、図13(B)の従来の横型発光ダイオードの順方向の素子抵抗は1500Ωと高く、電流を150mA以上に増加すると、素子が動作中に破壊するなど、安定な動作が得られない場合がある。   The current-voltage characteristics of the fabricated device during DC drive are described. In the vertical light emitting diode according to the present invention shown in FIG. 13A, electrical conductivity in the vertical direction can be obtained. In addition, the element resistance is as low as 10Ω, and it operates stably with DC drive even under high current conditions of about 1000mA. On the other hand, the device resistance in the forward direction of the conventional lateral light emitting diode of FIG. 13 (B) is as high as 1500Ω, and if the current is increased to 150 mA or more, the device may break during operation and stable operation may not be obtained. is there.

発光出力の直流駆動時における駆動電流依存性について述べる。本素子の発光波長は238nmである。尚、Al1-x4-y4Gax4Iny4N発光層のGa組成x4を0≦x4≦0.6とし、In組成y4を0≦y4≦0.1とすることで、発光波長を約200nmから300nmの遠紫外域に調整できる。図13(A)の本発明による縦型発光ダイオードにおいては、1000mA程度まで発光出力はほぼ線形的に増加する。しかし、図13(B)の従来の横型発光ダイオードにおいては、発熱のため、150mA程度で発光出力は飽和した。 The drive current dependency of the light emission output during DC driving will be described. The emission wavelength of this element is 238 nm. Incidentally, the Ga composition x4 of the Al 1-x4-y4 Ga x4 In y4 N light emitting layer is set to 0 ≦ x4 ≦ 0.6, and the In composition y4 is set to 0 ≦ y4 ≦ 0.1, so that the emission wavelength is about 200 nm to 300 nm. It can be adjusted to the ultraviolet region. In the vertical light emitting diode of the present invention shown in FIG. 13A, the light emission output increases almost linearly up to about 1000 mA. However, in the conventional lateral light emitting diode of FIG. 13B, the light emission output was saturated at about 150 mA due to heat generation.

本発明により、n型SiC基板上に高AlN組成AlGaInNを用いた縦型遠紫外発光ダイオードが実現する。   According to the present invention, a vertical far ultraviolet light emitting diode using a high AlN composition AlGaInN on an n-type SiC substrate is realized.

(実施例9)
・p型、AlN半導体発光素子
本発明に係るp型SiC基板とp型AlNの間に、p型AlN/Al1-x2-y2Gax2Iny2N超格子を挿入したことを特徴とする縦型発光ダイオードの構造について、図面を参照しながら説明する。また、比較のため、同様の半導体積層構造の横型発光ダイオードも作製した。
Example 9
P-type, AlN semiconductor light-emitting element A vertical type characterized by inserting a p-type AlN / Al 1-x2-y2 Ga x2 In y2 N superlattice between the p-type SiC substrate according to the present invention and the p-type AlN. The structure of the type light emitting diode will be described with reference to the drawings. For comparison, a lateral light emitting diode having a similar semiconductor multilayer structure was also produced.

図14(A)に、p型SiC基板とp型AlNの間に、p型AlN/Al1-x2-y2Gax2Iny2N超格子を挿入した縦型発光ダイオードの構造を示す。まず、MOCVD法により、p型6H-SiC(0001)基板1407上に、Mgドープp型AlN(膜厚3nm、Mg濃度5×1019cm-3)/Al0.5Ga0.45In0.05N(膜厚3nm、Mg濃度5×1019cm-3)超格子を100周期積層した超格子層1406、Mgドープp型AlN (膜厚0.2μm、Mg濃度5×1019cm-3) 層1405、Al0.8Ga0.18In0.02N(膜厚5nm)発光層1404、Siドープn型AlN (膜厚0.2μm、Si濃度5×1018cm-3) 層1403をエピタキシャル成長させる。なお、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下である。また、SiC基板1407上には、超格子層1406のうちAl組成の高いMgドープp型AlNから先に形成する。続いて、Siドープn型AlN層1403上にTi/Al/Ti/Au電極1401(サイズ150μm×150μm)を形成し、p型SiC基板1407裏面全面にNi/Au電極1402を形成する。 FIG. 14A shows the structure of a vertical light emitting diode in which a p-type AlN / Al 1-x2-y2 Ga x2 In y2 N superlattice is inserted between a p-type SiC substrate and p-type AlN. First, Mg-doped p-type AlN (film thickness: 3 nm, Mg concentration: 5 × 10 19 cm −3 ) / Al 0.5 Ga 0.45 In 0.05 N (film thickness) on a p-type 6H—SiC (0001) substrate 1407 by MOCVD. 3 nm, Mg concentration 5 × 10 19 cm −3 ) Superlattice layer 1406 in which 100 superlattices are laminated, Mg-doped p-type AlN (film thickness 0.2 μm, Mg concentration 5 × 10 19 cm −3 ) layer 1405, Al 0.8 A Ga 0.18 In 0.02 N (film thickness 5 nm) light emitting layer 1404 and a Si-doped n-type AlN (film thickness 0.2 μm, Si concentration 5 × 10 18 cm −3 ) layer 1403 are epitaxially grown. The residual oxygen concentration in the group III nitride semiconductor layer is 5 × 10 16 cm −3 or less. On the SiC substrate 1407, the Mg-doped p-type AlN having a high Al composition in the superlattice layer 1406 is formed first. Subsequently, a Ti / Al / Ti / Au electrode 1401 (size 150 μm × 150 μm) is formed on the Si-doped n-type AlN layer 1403, and a Ni / Au electrode 1402 is formed on the entire back surface of the p-type SiC substrate 1407.

図14(B)に、p型SiC基板とp型AlNの間に、p型AlN/Al1-x2-y2Gax2Iny2N超格子を挿入した横型発光ダイオードの構造を示す。まず、MOCVD法により、p型6H-SiC(0001)基板1407上に、Mgドープp型AlN(膜厚3nm、Mg濃度5×1019cm-3)/Al0.5Ga0.45In0.05N(膜厚3nm、Mg濃度5×1019cm-3)超格子を100周期積層した超格子層1406、Mgドープp型AlN (膜厚0.2μm、Mg濃度5×1019cm-3) 層1405、Al0.8Ga0.18In0.02N(膜厚5nm)発光層1404、Siドープn型AlN (膜厚0.2μm、Si濃度5×1018cm-3) 層1403をエピタキシャル成長させる。なお、III族窒化物半導体層中の残留酸素濃度は5×1016cm-3以下である。また、SiC基板1407上には、超格子層1406のうちAl組成の高いMgドープp型AlNから先に形成する。続いて、Siドープn型AlN層1403上にPd/Au電極1401(サイズ150μm×150μm)を形成し、その電極周辺部をエッチングにより除去し、露出したMgドープp型AlN層1405上にPd/Au電極1402を形成する。 FIG. 14B shows the structure of a lateral light emitting diode in which a p-type AlN / Al 1-x2-y2 Ga x2 In y2 N superlattice is inserted between a p-type SiC substrate and p-type AlN. First, Mg-doped p-type AlN (film thickness: 3 nm, Mg concentration: 5 × 10 19 cm −3 ) / Al 0.5 Ga 0.45 In 0.05 N (film thickness) on a p-type 6H—SiC (0001) substrate 1407 by MOCVD. 3 nm, Mg concentration 5 × 10 19 cm −3 ) Superlattice layer 1406 in which 100 superlattices are laminated, Mg-doped p-type AlN (film thickness 0.2 μm, Mg concentration 5 × 10 19 cm −3 ) layer 1405, Al 0.8 A Ga 0.18 In 0.02 N (film thickness 5 nm) light emitting layer 1404 and a Si-doped n-type AlN (film thickness 0.2 μm, Si concentration 5 × 10 18 cm −3 ) layer 1403 are epitaxially grown. The residual oxygen concentration in the group III nitride semiconductor layer is 5 × 10 16 cm −3 or less. On the SiC substrate 1407, the Mg-doped p-type AlN having a high Al composition in the superlattice layer 1406 is formed first. Subsequently, a Pd / Au electrode 1401 (size 150 μm × 150 μm) is formed on the Si-doped n-type AlN layer 1403, the periphery of the electrode is removed by etching, and a Pd / Au on the exposed Mg-doped p-type AlN layer 1405 is formed. An Au electrode 1402 is formed.

作製した素子の直流駆動時における電流−電圧特性について述べる。図14(A)の本発明による縦型発光ダイオードにおいては、縦方向の電気伝導性が得られる。また、素子抵抗も20Ωと低く、800mA程度の高電流条件下でも直流駆動で安定に動作した。一方、図14(B)の従来の横型発光ダイオードの順方向の素子抵抗は8000Ωと高く、電流を100mA以上に増加すると、素子が動作中に破壊するなど、安定な動作が得られない場合がある。   The current-voltage characteristics at the time of direct current driving of the manufactured element will be described. In the vertical light emitting diode according to the present invention shown in FIG. 14A, electrical conductivity in the vertical direction can be obtained. In addition, the device resistance was as low as 20Ω, and it operated stably under direct current drive even under high current conditions of about 800mA. On the other hand, the device resistance in the forward direction of the conventional lateral light emitting diode of FIG. 14B is as high as 8000 Ω, and if the current is increased to 100 mA or more, the device may be destroyed during operation and stable operation may not be obtained. is there.

発光出力の直流駆動時における駆動電流依存性について述べる。本素子の発光波長は225nmである。尚、Al1-x4-y4Gax4Iny4N発光層のGa組成x4を0≦x4≦0.6とし、In組成y4を0≦y4≦0.1とすることで、発光波長を約200nmから300nmの遠紫外域に調整できる。図14(A)の本発明による縦型発光ダイオードにおいては、800mA程度まで発光出力はほぼ線形的に増加する。しかし、図14(B)の従来の横型発光ダイオードにおいては、発熱のため、100mA程度で発光出力は飽和する。 The drive current dependency of the light emission output during DC driving will be described. The emission wavelength of this element is 225 nm. Incidentally, the Ga composition x4 of the Al 1-x4-y4 Ga x4 In y4 N light emitting layer is set to 0 ≦ x4 ≦ 0.6, and the In composition y4 is set to 0 ≦ y4 ≦ 0.1, so that the emission wavelength is about 200 nm to 300 nm. It can be adjusted to the ultraviolet region. In the vertical light emitting diode of the present invention shown in FIG. 14A, the light emission output increases almost linearly up to about 800 mA. However, in the conventional lateral light emitting diode of FIG. 14B, the light emission output is saturated at about 100 mA due to heat generation.

本発明により、p型SiC基板上にAlNを用いた縦型遠紫外発光ダイオードが実現する。   According to the present invention, a vertical far ultraviolet light emitting diode using AlN on a p-type SiC substrate is realized.

なお、本実施形態では、SiC基板として、n型4H-SiC(0001)もしくはp型6H-SiC(0001)を用いた場合を示した。本発明では、これらの基板を、n型4H-SiC(0001)、p型6H-SiC(0001)の代わりに、n型6H-SiC(0001)、n型4H-SiC(10-10)、n型6H-SiC(10-10)、n型4H-SiC(11-20)、n型6H-SiC(11-20)、p型6H-SiC(10-10)、p型6H-SiC(11-20)など異なるポリタイプ、面方位の基板に置き換えても同様な結果が得られる。   In the present embodiment, an n-type 4H—SiC (0001) or p-type 6H—SiC (0001) is used as the SiC substrate. In the present invention, these substrates are replaced with n-type 4H-SiC (0001), p-type 6H-SiC (0001), n-type 6H-SiC (0001), n-type 4H-SiC (10-10), n-type 6H-SiC (10-10), n-type 4H-SiC (11-20), n-type 6H-SiC (11-20), p-type 6H-SiC (10-10), p-type 6H-SiC ( Similar results can be obtained by substituting substrates with different polytypes and plane orientations such as 11-20).

本実施形態では、III族窒化物半導体(Al1-x-yGaxInyN)のn型伝導性はSiをドーピングする場合を示しが、本発明では、Siの代わりにGe、Sn、O、Sなどのドナー不純物をドーピングしても同様な結果が得られる。 In the present embodiment, the n-type conductivity of the group III nitride semiconductor (Al 1-xy Ga x In y N) shows a case where Si is doped. In the present invention, Ge, Sn, O, Similar results can be obtained by doping with a donor impurity such as S.

また、本実施形態では、III族窒化物半導体(Al1-x-yGaxInyN)のp型伝導性はMgをドーピングする場合を示したが、本発明では、Mgの代わりにZn、Be、Cd、Cなどのあく背プタ不純物をドーピングしても同様な効果が得られる。 In the present embodiment, the p-type conductivity of the group III nitride semiconductor (Al 1-xy Ga x In y N) is shown as being doped with Mg. However, in the present invention, Zn, Be are used instead of Mg. Similar effects can be obtained by doping dopant impurities such as Cd and C.

また、本実施形態では、III族窒化物半導体(Al1-x-yGaxInyN)の結晶成長方法には有機金属化学気相成長(MOCVD)法を用いる場合を示したが、本発明では、MOCVD法の代わりに分子線エピタキシー(MBE)法やハイドライド気相エピキタシー(HVPE)法などの成長方法を用いても同様な効果が得られる。 In the present embodiment, the case where the metal organic chemical vapor deposition (MOCVD) method is used as the crystal growth method of the group III nitride semiconductor (Al 1-xy Ga x In y N) is shown. Similar effects can be obtained by using a growth method such as molecular beam epitaxy (MBE) or hydride vapor phase epitaxy (HVPE) instead of MOCVD.

縦型素子構造と横型素子構造および電流分布の概略図である。It is the schematic of vertical element structure, horizontal element structure, and current distribution. Al1-xGaxNを用いた発光ダイオードの構造を示す図である。It is a diagram showing a structure of a light-emitting diode using the Al 1-x Ga x N. n型SiC基板上にn型Al1-x-yGaxInyNを積層した構造を示す図である。the n-type SiC substrate of n-type Al 1-xy Ga x In y N is a diagram showing a laminated structure. n型SiC基板上にn型Al1-x-yGaxInyNを積層した構造の素子においける電流−電圧特性を示す図である。n-type SiC n-type Al 1-xy on the substrate Ga x In y N a Keru placed element of the laminated structure current - is a graph showing voltage characteristics. n型SiCとn型AlNの間にn型AlN/AlGaInN超格子を挿入した場合のエネルギーバンドの概略図を示す図である。It is a figure which shows the schematic of the energy band at the time of inserting an n-type AlN / AlGaInN superlattice between n-type SiC and n-type AlN. n型SiC基板上にn型AlNを積層した構造を示す図である。It is a figure which shows the structure which laminated | stacked n-type AlN on the n-type SiC substrate. p型SiC基板上にp型Al1-x-yGaxInyNを積層した構造を示す図である。the p-type SiC substrate is a diagram showing a structure obtained by laminating a p-type Al 1-xy Ga x In y N. p型SiC基板上にp型AlNを積層した構造を示す図である。It is a figure which shows the structure which laminated | stacked p-type AlN on the p-type SiC substrate. n型SiC基板上に作製した縦型および横型Al1-x1-y1Gax1Iny1N系発光ダイオードの構造を示す図である。n-type SiC substrate on vertical produced in and is a diagram showing the lateral Al 1-x1-y1 Ga x1 In y1 N system structure of a light emitting diode. n型SiC基板上に作製した縦型および横型Al1-x1-y1Gax1Iny1N系発光ダイオードの電流−電圧特性を示す図である。It is a figure which shows the current-voltage characteristic of the vertical type and horizontal type Al1 -x1-y1 Gax1 Iny1 N type light emitting diode produced on the n-type SiC substrate. n型SiC基板上に作製した縦型および横型Al1-x1-y1Gax1Iny1N系発光ダイオードの発光強度−電流特性を示す図である。n vertical they fabricated in type SiC substrate and lateral Al 1-x1-y1 Ga x1 In y1 N -emitting intensity of the light emitting diodes - a graph showing the current characteristics. n型SiC基板上に作製した縦型および横型AlN系発光ダイオードの電流−電圧特性を示す図である。It is a figure which shows the current-voltage characteristic of the vertical type and horizontal type AlN type light emitting diode produced on the n-type SiC substrate. p型SiC基板上に作製した縦型および横型Al1-x1-y1Gax1Iny1N系発光ダイオードの構造を示した図である。FIG. 2 is a diagram showing the structure of vertical and horizontal Al 1-x1-y1 Ga x1 In y1 N-based light emitting diodes fabricated on a p-type SiC substrate. p型SiC基板上に作製した縦型および横型AlN系発光ダイオードの電流−電圧特性を示す図である。It is a figure which shows the current-voltage characteristic of the vertical type | mold and horizontal type | mold AlN type light emitting diode produced on the p-type SiC substrate.

符号の説明Explanation of symbols

301、302 Ti/Al/Ti/Au電極
303 Siドープn型Al0.4Ga0.55In0.05N層
304 Siドープn型Al0.8Ga0.15In0.05N/Al0.5Ga0.45In0.05N超格子を100周期積層した超格子層
305 n型4H-SiC(0001)基板
301, 302 Ti / Al / Ti / Au electrode 303 Si-doped n-type Al 0.4 Ga 0.55 In 0.05 N layer 304 Si-doped n-type Al 0.8 Ga 0.15 In 0.05 N / Al 0.5 Ga 0.45 In 0.05 N superlattice layered 100 periods Superlattice layer 305 n-type 4H-SiC (0001) substrate

Claims (13)

n型SiCから成る基板と、
前記基板上に形成されたn型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層と、
前記第1の窒化物半導体上に形成されたn型Al1-x-yGaxInyNから成る第2の窒化物半導体層と、
前記基板及び前記第2の窒化物半導体層にそれぞれ形成されたn型電極とを備え、
x≧x1かつy≧y1若しくはx≧x2かつy≧y2であることを特徴とするIII族窒化物半導体素子。
a substrate made of n-type SiC;
A first nitride semiconductor layer comprising an n-type Al 1-x1-y1 Ga x1 In y1 N / Al 1-x2-y2 Ga x2 In y2 N superlattice formed on the substrate;
A second nitride semiconductor layer made of n-type Al 1-xy Ga x In y N formed on the first nitride semiconductor;
N-type electrodes respectively formed on the substrate and the second nitride semiconductor layer,
A group III nitride semiconductor device, wherein x ≧ x1 and y ≧ y1 or x ≧ x2 and y ≧ y2.
n型SiCから成る基板と、
前記基板上に形成されたn型AlN/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層と、
前記第1の窒化物半導体上に形成されたn型AlNから成る第2の窒化物半導体層と、
前記基板及び前記第2の窒化物半導体層にそれぞれ形成されたn型電極とを備え、
Ga組成x2が0.2≦x2≦0.9であり、In組成y2が0≦y2≦0.1であることを特徴とするIII族窒化物半導体素子。
a substrate made of n-type SiC;
A first nitride semiconductor layer made of n-type AlN / Al 1-x2-y2 Ga x2 In y2 N superlattice formed on said substrate,
A second nitride semiconductor layer made of n-type AlN formed on the first nitride semiconductor;
N-type electrodes respectively formed on the substrate and the second nitride semiconductor layer,
A group III nitride semiconductor device, wherein the Ga composition x2 is 0.2 ≦ x2 ≦ 0.9, and the In composition y2 is 0 ≦ y2 ≦ 0.1.
n型SiCから成る基板と、
前記基板上に形成されたn型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層と、
前記第1の窒化物半導体上に形成されたn型Al1-x3-y3Gax3Iny3Nから成る第2の窒化物半導体層と、
前記第2の窒化物半導体上に形成されたAl1-x4-y4Gax4Iny4Nから成る発光層である第3の窒化物半導体層と、
前記第3の窒化物半導体上に形成されたp型Al1-x3-y3Gax3Iny3Nから成る第4の半導体層と、
前記基板に形成されたn型電極と、
前記第4の窒化物半導体層に形成されたp型電極とを備え、
0≦x3≦x4≦0.6かつ0≦y3≦y4≦0.1であることを特徴とするIII族窒化物半導体発光素子。
a substrate made of n-type SiC;
A first nitride semiconductor layer comprising an n-type Al 1-x1-y1 Ga x1 In y1 N / Al 1-x2-y2 Ga x2 In y2 N superlattice formed on the substrate;
A second nitride semiconductor layer made of n-type Al 1-x3-y3 Ga x3 In y3 N formed on the first nitride semiconductor;
A third nitride semiconductor layer which is a light emitting layer made of Al 1-x4-y4 Ga x4 In y4 N formed on the second nitride semiconductor;
A fourth semiconductor layer made of p-type Al 1-x3-y3 Ga x3 In y3 N formed on the third nitride semiconductor;
An n-type electrode formed on the substrate;
A p-type electrode formed on the fourth nitride semiconductor layer,
A group III nitride semiconductor light-emitting device, wherein 0 ≦ x3 ≦ x4 ≦ 0.6 and 0 ≦ y3 ≦ y4 ≦ 0.1.
n型SiCから成る基板と、
前記基板上に形成されたn型AlN/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層と、
前記第1の窒化物半導体上に形成されたn型AlNから成る第2の窒化物半導体層と、
前記第2の窒化物半導体上に形成されたAl1-x4-y4Gax4Iny4Nから成る発光層である第3の窒化物半導体層と、
前記第3の窒化物半導体上に形成されたp型AlNから成る第4の窒化物半導体層と、
前記基板に形成されたn型電極と、
前記第4の窒化物半導体層に形成されたp型電極とを備え、
Ga組成x2が0.2≦x2≦0.9であり、In組成y2が0≦y2≦0.1であり、Ga組成x4が0≦x4≦0.6であり、In組成y4が0≦y4≦0.1であることを特徴とするIII族窒化物半導体発光素子。
a substrate made of n-type SiC;
A first nitride semiconductor layer made of n-type AlN / Al 1-x2-y2 Ga x2 In y2 N superlattice formed on said substrate,
A second nitride semiconductor layer made of n-type AlN formed on the first nitride semiconductor;
A third nitride semiconductor layer which is a light emitting layer made of Al 1-x4-y4 Ga x4 In y4 N formed on the second nitride semiconductor;
A fourth nitride semiconductor layer made of p-type AlN formed on the third nitride semiconductor;
An n-type electrode formed on the substrate;
A p-type electrode formed on the fourth nitride semiconductor layer,
Ga composition x2 is 0.2 ≦ x2 ≦ 0.9, In composition y2 is 0 ≦ y2 ≦ 0.1, Ga composition x4 is 0 ≦ x4 ≦ 0.6, and In composition y4 is 0 ≦ y4 ≦ 0.1 A group III nitride semiconductor light emitting device.
p型SiCから成る基板と、
前記基板上に形成されたp型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層と、
前記第1の窒化物半導体層上に形成されたn型Al1-x-yGaxInyNから成る第2の窒化物半導体層と、
前記基板及び前記第2の窒化物半導体層にそれぞれ形成されたp型電極とを備え、
x≧x1かつy≧y1若しくはx≧x2かつy≧y2であることを特徴とするIII族窒化物半導体素子。
a substrate made of p-type SiC;
A first nitride semiconductor layer comprising a p-type Al 1-x1-y1 Ga x1 In y1 N / Al 1-x2-y2 Ga x2 In y2 N superlattice formed on the substrate;
A second nitride semiconductor layer made of n-type Al 1-xy Ga x In y N formed on the first nitride semiconductor layer;
P-type electrodes respectively formed on the substrate and the second nitride semiconductor layer,
A group III nitride semiconductor device, wherein x ≧ x1 and y ≧ y1 or x ≧ x2 and y ≧ y2.
p型SiCから成る基板と、
前記基板上に形成されたp型AlN/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層と、
前記第1の窒化物半導体層上に形成されたn型AlNから成る第2の窒化物半導体層と、
前記基板及び前記第2の窒化物半導体層にそれぞれ形成されたp型電極とを備え、
Ga組成x2が0.2≦x2≦0.9であり、In組成y2が0≦y2≦0.1であることを特徴とするIII族窒化物半導体素子。
a substrate made of p-type SiC;
A first nitride semiconductor layer made of p-type AlN / Al 1-x2-y2 Ga x2 In y2 N superlattice formed on said substrate,
A second nitride semiconductor layer made of n-type AlN formed on the first nitride semiconductor layer;
P-type electrodes respectively formed on the substrate and the second nitride semiconductor layer,
A group III nitride semiconductor device, wherein the Ga composition x2 is 0.2 ≦ x2 ≦ 0.9, and the In composition y2 is 0 ≦ y2 ≦ 0.1.
p型SiCから成る基板と、
前記基板上に形成されたp型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層と、
前記第1の窒化物半導体上に形成されたp型Al1-x3-y3Gax3Iny3Nから成る第2の窒化物半導体層と、
前記第2の窒化物半導体層上に形成されたAl1-x4-y4Gax4Iny4Nから成る発光層である第3の窒化物半導体層と、
前記第3の窒化物半導体層上に形成されたn型Al1-x3-y3Gax3Iny3Nから成る第4の窒化物半導体層と、
前記基板に形成されたp型電極と、
前記第4の窒化物半導体層に形成されたn型電極とを備え、
0≦x3≦x4≦0.6かつ0≦y3≦y4≦0.1としたことを特徴とするIII族窒化物半導体素子。
a substrate made of p-type SiC;
A first nitride semiconductor layer comprising a p-type Al 1-x1-y1 Ga x1 In y1 N / Al 1-x2-y2 Ga x2 In y2 N superlattice formed on the substrate;
A second nitride semiconductor layer made of p-type Al 1-x3-y3 Ga x3 In y3 N formed on the first nitride semiconductor;
A third nitride semiconductor layer which is a light emitting layer made of Al 1-x4-y4 Ga x4 In y4 N formed on the second nitride semiconductor layer;
A fourth semiconductor layer consisting of the first 3 n-type formed in the nitride semiconductor layer of Al 1-x3-y3 Ga x3 In y3 N,
A p-type electrode formed on the substrate;
An n-type electrode formed on the fourth nitride semiconductor layer,
A group III nitride semiconductor device, wherein 0 ≦ x3 ≦ x4 ≦ 0.6 and 0 ≦ y3 ≦ y4 ≦ 0.1.
p型SiCから成る基板と、
前記基板上に形成されたp型AlN/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層と、
前記第1の窒化物半導体上に形成されたp型AlNから成る第2の窒化物半導体層と、
前記第2の窒化物半導体層上に形成されたAl1-x4-y4Gax4Iny4Nから成る発光層である第3の窒化物半導体層と、
前記第3の窒化物半導体層上に形成されたn型AlNから成る第4の窒化物半導体層と、
前記基板に形成されたp型電極と、
前記第4の窒化物半導体層に形成されたn型電極とを備え、
Ga組成x2が0.2≦x2≦0.9であり、In組成y2が0≦y2≦0.1であり、Ga組成x4が0≦x4≦0.6であり、In組成y4が0≦y4≦0.1であることを特徴とするIII族窒化物半導体素子。
a substrate made of p-type SiC;
A first nitride semiconductor layer made of p-type AlN / Al 1-x2-y2 Ga x2 In y2 N superlattice formed on said substrate,
A second nitride semiconductor layer made of p-type AlN formed on the first nitride semiconductor;
A third nitride semiconductor layer which is a light emitting layer made of Al 1-x4-y4 Ga x4 In y4 N formed on the second nitride semiconductor layer;
A fourth nitride semiconductor layer made of n-type AlN formed on the third nitride semiconductor layer;
A p-type electrode formed on the substrate;
An n-type electrode formed on the fourth nitride semiconductor layer,
Ga composition x2 is 0.2 ≦ x2 ≦ 0.9, In composition y2 is 0 ≦ y2 ≦ 0.1, Ga composition x4 is 0 ≦ x4 ≦ 0.6, and In composition y4 is 0 ≦ y4 ≦ 0.1 Group III nitride semiconductor device.
前記第1の窒化物半導体層は、平均Al組成が前記基板から前記第2の窒化物半導体層に向けて増加していることを特徴とする請求項1乃至8のいずれかに記載のIII族窒化物半導体素子。   9. The group III according to claim 1, wherein the first nitride semiconductor layer has an average Al composition increasing from the substrate toward the second nitride semiconductor layer. 10. Nitride semiconductor device. n型SiCから成る基板上にAlGaInNから成る窒化物半導体を積層したIII族窒化物半導体素子の作製方法であって、
前記基板上にn型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層を形成するステップであって、Al組成の高い層から先に形成する第1の窒化物半導体層を形成するステップと、
前記第1の窒化物半導体層上にn型Al1-x-yGaxInyNから成る第2の窒化物半導体層を形成するステップと、
前記基板及び前記第2の窒化物半導体層にn型電極をそれぞれ形成するステップと
を有することを特徴とするIII族窒化物半導体素子の作製方法。
A method for producing a group III nitride semiconductor device in which a nitride semiconductor made of AlGaInN is laminated on a substrate made of n-type SiC,
Forming a first nitride semiconductor layer comprising an n-type Al 1-x1-y1 Ga x1 In y1 N / Al 1-x2-y2 Ga x2 In y2 N superlattice on the substrate, the Al composition Forming a first nitride semiconductor layer that is formed first from a higher layer;
Forming a second nitride semiconductor layer made of n-type Al 1-xy Ga x In y N on the first nitride semiconductor layer;
Forming a group III nitride semiconductor device, comprising forming n-type electrodes on the substrate and the second nitride semiconductor layer, respectively.
p型SiCから成る基板上にAlGaInNから成る窒化物半導体を積層したIII族窒化物半導体素子の作製方法であって、
前記基板上にp型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層を形成するステップであって、Al組成の高い層から先に形成する第1の窒化物半導体層を形成するステップと、
前記第1の窒化物半導体層上にp型Al1-x-yGaxInyNから成る第2の窒化物半導体層を形成するステップと、
前記基板及び前記第2の窒化物半導体層にp型電極をそれぞれ形成するステップと
を有することを特徴とするIII族窒化物半導体素子の作製方法。
A method for producing a group III nitride semiconductor device in which a nitride semiconductor made of AlGaInN is laminated on a substrate made of p-type SiC,
Forming a first nitride semiconductor layer comprising a p-type Al 1-x1-y1 Ga x1 In y1 N / Al 1-x2-y2 Ga x2 In y2 N superlattice on the substrate, the Al composition Forming a first nitride semiconductor layer that is formed first from a higher layer;
Forming a second nitride semiconductor layer made of p-type Al 1-xy Ga x In y N on the first nitride semiconductor layer;
Forming a p-type electrode on the substrate and the second nitride semiconductor layer, respectively.
n型SiC基板上にAlGaInNから成る窒化物半導体を積層したIII族窒化物半導体素子の作製方法であって、
前記SiC基板上にn型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層を形成するステップであって、Al組成の高い層から先に形成する第1の窒化物半導体層を形成するステップと、
前記第1の窒化物半導体層上にn型Al1-x3-y3Gax3Iny3Nから成る第2の窒化物半導体層を形成するステップと、
前記第2の窒化物半導体層上にAl1-x4-y4Gax4Iny4Nから成る発光層である第3の窒化物半導体層を形成するステップと、
前記第3の窒化物半導体上にp型Al1-x3-y3Gax3Iny3Nから成る第4の半導体層を形成するステップと
前記基板にn型電極を形成するステップと
前記第4の窒化物半導体層にp型電極を形成するステップと
を有することを特徴とするIII族窒化物半導体素子の作製方法。
A method for producing a group III nitride semiconductor device in which a nitride semiconductor composed of AlGaInN is stacked on an n-type SiC substrate,
Forming a first nitride semiconductor layer comprising an n-type Al 1-x1-y1 Ga x1 In y1 N / Al 1-x2-y2 Ga x2 In y2 N superlattice on the SiC substrate, Forming a first nitride semiconductor layer formed first from a layer having a high composition;
Forming a second nitride semiconductor layer made of n-type Al 1-x3-y3 Ga x3 In y3 N on the first nitride semiconductor layer;
Forming a third nitride semiconductor layer which is a light emitting layer made of Al 1-x4-y4 Ga x4 In y4 N on the second nitride semiconductor layer;
Forming a fourth semiconductor layer made of p-type Al 1-x3-y3 Ga x3 In y3 N on the third nitride semiconductor, forming an n-type electrode on the substrate, and the fourth nitride And a step of forming a p-type electrode on the oxide semiconductor layer.
p型SiC基板上にAlGaInNから成る窒化物半導体を積層したIII族窒化物半導体素子の作製方法であって、
前記SiC基板上にp型Al1-x1-y1Gax1Iny1N/ Al1-x2-y2Gax2Iny2N超格子から成る第1の窒化物半導体層を形成するステップであって、Al組成の高い層から先に形成する第1の窒化物半導体層を形成するステップと、
前記第1の窒化物半導体層上にp型Al1-x3-y3Gax3Iny3Nから成る第2の窒化物半導体層を形成するステップと、
前記第2の窒化物半導体層上にAl1-x4-y4Gax4Iny4Nから成る発光層である第3の窒化物半導体層を形成するステップと、
前記第3の窒化物半導体上にn型Al1-x3-y3Gax3Iny3Nから成る第4の半導体層を形成するステップと
前記基板にp型電極を形成するステップと
前記第4の窒化物半導体層にn型電極を形成するステップと
を有することを特徴とするIII族窒化物半導体素子の作製方法。
A method for producing a group III nitride semiconductor device in which a nitride semiconductor composed of AlGaInN is stacked on a p-type SiC substrate,
Forming a first nitride semiconductor layer comprising a p-type Al 1-x1-y1 Ga x1 In y1 N / Al 1-x2-y2 Ga x2 In y2 N superlattice on the SiC substrate, comprising Al Forming a first nitride semiconductor layer formed first from a layer having a high composition;
Forming a second nitride semiconductor layer made of p-type Al 1-x3-y3 Ga x3 In y3 N on the first nitride semiconductor layer;
Forming a third nitride semiconductor layer which is a light emitting layer made of Al 1-x4-y4 Ga x4 In y4 N on the second nitride semiconductor layer;
Forming a fourth semiconductor layer made of n-type Al 1-x3-y3 Ga x3 In y3 N on the third nitride semiconductor; forming a p-type electrode on the substrate; and the fourth nitride And a step of forming an n-type electrode on the oxide semiconductor layer.
JP2006247232A 2006-09-12 2006-09-12 Group iii nitride semiconductor element and method for manufacturing the same Pending JP2008071832A (en)

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