JP2006278570A - Schottky diode, field effect transistor, and their manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a Schottky diode and a field effect transistor with high breakdown voltage and high operation voltage. <P>SOLUTION: The Schottky diode includes an undoped AlN layer 32 stacked on a semi-insulating substrate 31, an Si-doped n-type AlN layer 33 stacked on the AlN layer 32, an ohmic electrode 36 formed on the Si-doped n-type AlN layer 33 via a highly concentrated Si-doped n-type AlN layer 34, and a Schottky electrode 35 formed on the Si-doped n-type AlN layer 33. The Si concentration of the Si-doped n-type AlN layer 33 ranges from 5×10<SP>16</SP>to 5×10<SP>18</SP>cm<SP>-3</SP>, and the Si concentration of the layer Si-doped n-type AlN 34 is 5×10<SP>19</SP>cm<SP>-3</SP>or higher. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a Schottky diode, a field effect transistor, and a manufacturing method thereof, and more particularly, to a Schottky diode, a field effect transistor, and a manufacturing method thereof, which are high-power electronic devices having a high breakdown voltage and a high operating voltage.

  In various fields such as wireless communication, electric vehicles, and power control, higher output, higher frequency, and lower loss of semiconductor electronic devices are desired. Furthermore, use in a severe environment such as a high temperature environment or under irradiation with radiation has been demanded. When pursuing such strict specifications, the operating limit of the semiconductor device is limited by the physical property value of the semiconductor material, so that a semiconductor material having a large band gap energy and a high breakdown electric field strength is superior. Aluminum nitride (AlN) has the highest band gap energy and the highest breakdown field strength in a semiconductor, and exhibits a thermal conductivity similar to that of metal. For this reason, AlN is a semiconductor material that can dramatically improve performance compared to conventional Si, SiC, and GaN-based high-power electronic devices. Expected.

  In order to produce a high-power electronic device using AlN, it is essential to develop peripheral technologies. However, at present, even an electrode formation technique that is indispensable for manufacturing a device has not been established. In general, as the band gap of a semiconductor material increases, it becomes difficult to form ohmic electrodes and Schottky electrodes having good characteristics. Since AlN has the largest band gap energy among semiconductors, it is extremely difficult to form ohmic electrodes and Schottky electrodes having good characteristics. For this reason, it is very difficult to produce a high-power electronic device that requires a good ohmic electrode and a Schottky electrode in AlN.

Soejima Narimasa et al., “Evaluation of Vertical Schottky Diodes Using GaN Substrates”, Japan Society of Applied Physics, Autumn 65th Annual Conference, Proceedings 1a-ZK-1, 2004 Gen Okumura, "Current Status and Future Development of Wide Gap Semiconductor High Frequency Electronic Devices", Applied Physics, Vol. 73, No. 3, pp. 315-326, 2004

A report example of a conventional high-power electronic device using GaN will be described below. FIG. 1 shows a conventional Schottky diode using GaN (for example, see Non-Patent Document 1). This Schottky diode is manufactured by using a metal organic chemical vapor deposition (MOCVD) method on an n-type GaN substrate 11 and an n-type GaN layer 12 doped with Si (thickness 5 μm, carrier concentration 6 × 10 ^16). cm ⁻³ ). Next, a Pt electrode 13 (Schottky electrode) is formed on the n-type GaN layer 12, and an Al / Au electrode 14 (ohmic electrode) is formed on the substrate 11.

  The element withstand voltage of this Schottky diode is about 90V. In this structure, since the device breakdown voltage is determined by the GaN breakdown field strength, the device breakdown voltage cannot be increased beyond the limit derived from the physical property constants. Therefore, with this structure, a Schottky diode with extremely high device breakdown voltage cannot be manufactured.

  As a high-power transistor using GaN, a GaN-based heterostructure field effect transistor is generally used (see, for example, Non-Patent Document 2). FIG. 2 shows a conventional GaN-based heterostructure field effect transistor. The basic structure of the field effect transistor is a single heterostructure in which a thick undoped GaN layer 22 of 1 μm or more is grown on a substrate 21 such as sapphire or SiC and an undoped or Si-doped AlGaN cap layer 23 is grown thereon. It is done. A source electrode 24, a gate electrode 25, and a drain electrode 26 are formed on the AlGaN cap layer 23.

  A two-dimensional electron gas is generated at the interface between the GaN layer 22 and the AlGaN cap layer 23. In order to grow the AlGaN cap layer 23 on the GaN layer 22, a large tensile strain is introduced into the AlGaN cap layer 23. In order to suppress the occurrence of crystal defects due to this tensile strain, the Al composition X of the AlGaN cap layer 23 needs to be 0.3 or less. In the structure in which the gate electrode 25 is formed on the AlGaN cap layer 23 having an Al composition X of about 0.3, the gate leakage current inevitably increases. A large gate leakage current has a problem of reducing the operating voltage of the field effect transistor.

  In this structure, in order to obtain a high carrier concentration, the AlGaN cap layer 23 needs to be about 20 nm or more. However, when the AlGaN cap layer 23 is thick, there is a problem that the mutual conductance is lowered. Furthermore, in this structure, the maximum operating voltage is limited by the dielectric breakdown strength of GaN, and is as low as about 50 V to 80 V due to the limit derived from its physical property constant. Therefore, a GaN-based heterostructure field effect transistor cannot produce a field effect transistor with extremely excellent high output characteristics.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a Schottky diode, a field effect transistor, and a manufacturing method thereof having a high withstand voltage and a high operating voltage.

In order to achieve the above object, the present invention provides a Schottky diode comprising: an undoped AlN layer stacked on a semi-insulating substrate; and an undoped AlN layer on the undoped AlN layer. A laminated Si-doped n-type AlN layer, an ohmic electrode formed on the Si-doped n-type AlN layer via a high-concentration Si-doped n-type AlN layer, and formed on the Si-doped n-type AlN layer The Si concentration of the Si-doped n-type AlN layer is 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ , and the Si concentration of the high-concentration Si-doped n-type AlN layer Is 5 × 10 ¹⁹ cm ⁻³ or more.

The invention according to claim 2 is a vertical Schottky diode, a substrate made of any one of n-type AlN and n-type SiC whose growth surface is a (0001) plane, and is laminated on the substrate. A Si-doped n-type AlN layer having a Si concentration of 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ , a Schottky electrode formed on the Si-doped n-type AlN layer, and a back surface of the substrate And an ohmic electrode formed thereon.

The invention according to claim 3 is a vertical Schottky diode, a substrate made of any one of n-type AlN and n-type SiC whose growth surface is a (000-1) plane, and laminated on the substrate. An Si-doped n-type AlN layer, a high-concentration Si-doped n-type AlN layer stacked on the Si-doped n-type AlN layer, an ohmic electrode formed on the high-concentration Si-doped n-type AlN layer, A Si concentration of the Si-doped n-type AlN layer is 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ , and the high-concentration Si-doped The Si concentration of the n-type AlN layer is 5 × 10 ¹⁹ cm ⁻³ or more.

The invention according to claim 9 is a field effect transistor, comprising an undoped AlN layer laminated on a semi-insulating substrate, a Si doped n-type AlN layer laminated on the undoped AlN layer, and the Si doped a drain electrode and a source electrode formed on the n-type AlN layer via a high-concentration Si-doped n-type AlN layer; and a gate electrode formed on the Si-doped n-type AlN layer, the Si-doped nN The Si concentration of the type AlN layer is 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ , and the Si concentration of the high concentration Si-doped n-type AlN layer is 5 × 10 ¹⁹ cm ⁻³ or more. It is characterized by that.

The invention according to claim 10 is an AlN / AlGaN / AlN field effect transistor, comprising an undoped AlN layer laminated on a semi-insulating substrate, and an Si-doped n-type AlN layer laminated on the undoped AlN layer. An Al _X Ga _1-X N channel layer stacked on the Si-doped n-type AlN layer, an AlN cap layer stacked on the Al _X Ga _1-X N channel layer, and the AlN cap layer A drain electrode and a source electrode formed through a high-concentration Si-doped n-type AlN layer, and a gate electrode formed on the AlN cap layer, and the Si concentration of the Si-doped n-type AlN layer is: 5 is a ^{× 10 16 cm -3 ~5 × 10} 18 cm -3, Al composition X of the _Al X _{Ga 1-X} N channel layer is 0.9 or less, the _Al X Ga _{1 X} N film thickness of the channel layer t (nm) satisfies the relation of t <20 + 200 × X, Si concentration of the high concentration Si-doped n-type AlN layer, characterized in that 5 × ¹⁰ 19 ^{cm -3} or more And

The invention according to claim 11 is an AlN / AlGaN / AlN field effect transistor, comprising an undoped AlN layer stacked on a semi-insulating substrate, and an Si-doped n-type AlN layer stacked on the undoped AlN layer. An Al _X Ga _1-X N channel layer stacked on the Si-doped n-type AlN layer, an AlN cap layer stacked on the Al _X Ga _1-X N channel layer, and the AlN cap layer, A drain electrode and a source electrode formed through a high-concentration Si-doped n-type Al _Y Ga _1-Y N layer in a portion from which a part of the Al _X Ga _1-X N channel layer is removed, and the AlN cap layer and a gate electrode formed above, Si concentration in the Si-doped n-type AlN layer is ^{5 × 10 16 cm -3 ~5 ×} 10 18 cm -3, the _Al X Ga ₁ Al composition X of _X N channel layer is 0.9 or less, the _Al X _{Ga 1-X} N film thickness of the channel layer t (nm) satisfies the relation of t <20 + 200 × X, the high concentration Si The Si concentration of the doped n-type Al _Y Ga _1-Y N layer is 5 × 10 ¹⁹ cm ⁻³ or more, and the relationship between the Al composition X and Y is Y ≦ X.

The invention according to claim 12 is an AlN / Si / AlN field effect transistor comprising an undoped AlN layer laminated on a semi-insulating substrate, a monomolecular layer laminated on the undoped AlN layer. A high-concentration Si layer is formed on the following Si layer, an AlN cap layer having a thickness of 15 nm or less laminated on the Si layer, and a portion from which the AlN cap layer, the Si layer, and the undoped AlN layer are partially removed. A drain electrode and a source electrode formed via a doped n-type AlN layer; and a gate electrode formed on the AlN cap layer, wherein the Si concentration of the high-concentration Si-doped n-type AlN layer is 1 × 10 ^{It is 19} cm ⁻³ or more.

The invention according to claim 13 is an AlN / Si / AlN field effect transistor, comprising an undoped AlN layer laminated on a semi-insulating substrate and a monomolecular layer laminated on the undoped AlN layer. The following Si layer, an AlN cap layer having a thickness of 15 nm or less laminated on the Si layer, and a drain electrode and a source formed on the AlN cap layer via a high-concentration Si-doped n-type AlN layer An electrode and a gate electrode formed on the AlN cap layer are provided, and the Si concentration of the high-concentration Si-doped n-type AlN layer is 1 × 10 ¹⁹ cm ⁻³ or more.

  As described above, according to the present invention, since a Schottky diode or a field effect transistor is manufactured using a Si-doped n-type AlN layer with a limited Si concentration, high-power electrons that operate with a high breakdown voltage and a high operating voltage. A device can be manufactured.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present embodiment is characterized in that a Si-doped n-type AlN layer with a limited Si concentration is applied to a high-power electronic device. By using a Si-doped n-type AlN layer with a limited Si concentration, the breakdown voltage of the Schottky diode can be significantly increased, and the operating voltage of the field effect transistor can be significantly increased.

(Production of Schottky diode)
FIG. 3 shows a Schottky diode using a Si-doped n-type AlN layer. (A) is a top view, (b) is a cross-sectional view. In the Schottky diode, an undoped AlN layer 32 and a Si-doped n-type AlN layer 33 are sequentially stacked on an AlN (0001) substrate 31 that is a semi-insulating substrate. Further, a Schottky electrode 35 and an ohmic electrode 36 formed on the high-concentration Si-doped n-type AlN layer 34 are stacked on the Si-doped n-type AlN layer 33.

The Schottky diode is manufactured by the MOCVD method. Trimethylaluminum (TMA) is used as the Al material, trimethylgallium (TMG) is used as the Ga material, ammonia (NH ₃ ) is used as the N material, and silane (SiH ₄ ) is used as the Si material. The growth temperature is 1100 ° C. There are two manufacturing methods: (A) a method using etching and (B) a method using regrowth.

FIG. 4 shows a method for producing the Schottky diode of Example 1 by (A) etching. (FIG. 4 (a)) On the AlN (0001) substrate 31, an undoped AlN layer 32 having a film thickness of 0.5 μm and a Si-doped n-type film having a film thickness of 4 μm and a Si concentration of 1 × 10 ¹⁷ cm ⁻³ are formed by MOCVD. An AlN layer 33 and a high-concentration Si-doped n-type AlN layer 34 having a thickness of 10 nm and a Si concentration of 5 × 10 ¹⁹ cm ⁻³ are epitaxially grown. (FIG. 4B) An ohmic electrode (Ti / Al / Ti / Au) 36 is formed on the high-concentration Si-doped n-type AlN layer 34.

  (FIG. 4C) A part of the high-concentration Si-doped n-type AlN layer 34 is removed by dry etching (reactive ion etching) using chlorine gas until the Si-doped n-type AlN layer 33 is exposed. (FIG. 4D) A Schottky electrode (Pd / Au) 35 is formed on the exposed Si-doped n-type AlN layer 33.

FIG. 5 shows a method for manufacturing the Schottky diode of Example 1 by (B) regrowth. (FIG. 5A) On the AlN (0001) substrate 31, an undoped AlN layer 32 having a film thickness of 0.5 μm and a Si-doped n-type film having a film thickness of 4 μm and a Si concentration of 1 × 10 ¹⁷ cm ⁻³ are formed by MOCVD. The AlN layer 33 is epitaxially grown. (FIG. 5B) A SiO ₂ mask 37 is deposited on the Si-doped n-type AlN layer 33 by sputtering. (FIG. 5C) A high-concentration Si-doped n-type AlN layer 34 having a film thickness of 10 nm and a Si concentration of 5 × 10 ¹⁹ cm ⁻³ is regrown by MOCVD.

(FIG. 5D) The SiO ₂ mask 37 and the high-concentration Si-doped n-type AlN layer 34 on the SiO ₂ mask 37 are removed by lift-off. (FIG. 5E) An ohmic electrode 36 is formed on the high-concentration Si-doped n-type AlN layer 34 formed by regrowth. (FIG. 5F) A Schottky electrode 35 is formed on the Si-doped n-type AlN layer 33.

  FIG. 6 shows current-voltage characteristics of the Schottky diode of Example 1. (A) is a Schottky diode fabricated by etching, (B) is a Schottky diode fabricated by regrowth, and (X) is a current-voltage characteristic of a Schottky diode fabricated using conventional GaN. It is. A conventional Schottky diode has a withstand voltage of about 90 V because a reverse current starts to flow at a reverse voltage of 90 V. In Example 1, (A) the breakdown voltage of the Schottky diode fabricated by etching is 900V, and (B) the breakdown voltage of the Schottky diode fabricated by regrowth is 920V. Compared with the prior art, the breakdown voltage of the Schottky diode can be increased about 10 times.

  The reason why such a high breakdown voltage can be obtained is that the dielectric breakdown field strength of AlN is larger than that of GaN, and the Schottky barrier between AlN and the Schottky electrode is very high, and the leakage current is extremely low.

  In general, when a semiconductor surface is etched, processing damage is introduced, thereby reducing the breakdown voltage. However, in Example 1, the Schottky diode exhibits substantially the same high breakdown voltage regardless of (A) the method using etching and (B) the method using regrowth. In the case of AlN, the reason why good Schottky characteristics can be obtained even if etching is performed is that epitaxially grown AlN with good crystal quality has a strong interatomic bonding force and is difficult to be damaged by etching. It is because it has. If etching can be used in the manufacturing process of an electronic device, the degree of freedom in device design can be increased.

(Si concentration range of Si-doped n-type AlN layer)
FIG. 7 shows the relationship between the Si concentration and the breakdown voltage of the Si-doped n-type AlN layer. In Example 1, the Si concentration of the Si-doped n-type AlN layer 33 was set to 1 × 10 ¹⁷ cm ⁻³ . Here, Schottky diodes were manufactured by changing the Si concentration by the regrowth method shown in FIG. A breakdown voltage of 500 V or more is obtained when the Si concentration is 5 × 10 ¹⁸ cm ⁻³ or less. When the Si concentration is 5 × 10 ¹⁶ cm ⁻³ , the breakdown voltage increases to 1000V. However, the Schottky diode does not operate at 5 × 10 ¹⁶ cm ⁻³ or less. This is because n-type AlN having high conductivity cannot be obtained when the Si concentration is 5 × 10 ¹⁶ cm ⁻³ or less.

On the other hand, when the Si concentration is 5 × 10 ¹⁸ cm ⁻³ or more, the breakdown voltage rapidly decreases as the Si concentration increases. Accordingly, by setting the Si concentration of the Si-doped n-type AlN in the range of 5 × 10 ¹⁶ cm ⁻³ to 5 × 10 ¹⁸ cm ⁻³ , a high breakdown voltage Schottky diode can be manufactured.

(Si concentration range of high-concentration Si-doped n-type AlN layer)
In Example 1, a high-concentration Si-doped n-type AlN layer 34 is inserted between the ohmic electrode 36 and the Si-doped n-type AlN layer 33. In a high-power electronic device, it is necessary to reduce the contact resistance of the ohmic electrode 36 in order to reduce power loss. FIG. 8 shows the relationship between the Si concentration of the high-concentration Si-doped n-type AlN layer and the contact resistance.

The contact resistance was determined using the transmission line (TLM) method. When the Si concentration is 5 × 10 ¹⁸ cm ⁻³ or less, the contact resistance is as high as 2 × 10 ⁻⁴ Ωcm ² . By setting the Si concentration to 1 × 10 ¹⁹ cm ⁻³ or more, the contact resistance is greatly reduced to 1 × 10 ⁻⁴ Ωcm ² or less. Furthermore, when the Si concentration is 5 × 10 ¹⁹ cm ⁻³ or more, the contact resistance can be reduced to 2 × 10 ⁻⁵ Ωcm ² or less. Therefore, by setting the Si concentration of the high-concentration Si-doped n-type AlN layer 34 inserted between the ohmic electrode 36 and the Si-doped n-type AlN layer 33 to 1 × 10 ¹⁹ cm ⁻³ or more, power loss is extremely high. Low high power electronic devices can be fabricated.

(Thickness of high-concentration Si-doped n-type AlN layer)
As described with reference to FIG. 5, when a Schottky diode is produced by regrowth, the SiO ₂ mask 37 and the heavily doped Si-doped n-type AlN layer 34 on the SiO ₂ mask are removed by lift-off (FIG. 5 ( c) to (d)). In the case of a conventional Schottky diode using GaN, since GaN does not deposit on the SiO ₂ mask, GaN can be easily removed. However, AlN and _{Al Y Ga 1-Y N (} 0 <Y <1, below, displays the range of the composition is omitted) contains Al in the case of, AlN on the SiO ₂ mask and _Al Y _{Ga 1- As YN} accumulates, it becomes difficult to remove them.

FIG. 9 shows the relationship between the film thickness of the high-concentration Si-doped n-type Al _Y Ga _1-Y N layer that can be removed by lift-off and the Al composition. When the high-concentration Si-doped n-type Al _Y Ga _1-Y N layer is regrown, the case where it can be removed by lift-off is indicated by 〇, and the case where it cannot be indicated by x. In the case of high-concentration Si-doped n-type AlN (Al composition Y = 1), it can be seen that if the film thickness is 100 nm or less, it can be removed by lift-off. The film thickness of the high-concentration Si-doped n-type Al _Y Ga _1-Y N layer that can be removed by lift-off increases as the Al composition Y decreases. From this, in the case of forming a high-concentration Si-doped n-type _Al Y _{Ga 1-Y} N layers using regrowth, the film thickness to 100nm or less.

(Substrate material)
In Example 1, a semi-insulating AlN (0001) substrate is used as the insulating substrate. Table 1 shows the results of examining the relationship between the substrate material and the withstand voltage.

  As described with reference to FIG. 5, a Schottky diode was produced by regrowth. As an insulating substrate, a semi-insulating AlN (0001) substrate, a semi-insulating SiC (0001) substrate, an insulating sapphire (0001) substrate, a semi-insulating GaN (0001) substrate, a semi-insulating GaAs (111) substrate, and A semi-insulating Si (111) substrate was examined. A breakdown voltage of 500 V or more was obtained only in the semi-insulating AlN (0001) substrate, the semi-insulating SiC (0001) substrate, and the insulating sapphire (0001) substrate. Accordingly, in a high-power electronic device using Si-doped n-type AlN, any one of a semi-insulating AlN (0001) substrate, a semi-insulating SiC (0001) substrate, and an insulating sapphire (0001) substrate is used as the insulating substrate. It can be seen that is used.

FIG. 10 shows a vertical Schottky diode using Si-doped n-type AlN according to Example 2-1. (C) A Schottky diode using an n-type AlN substrate whose growth surface is the (0001) plane. First, (1) a Si-doped n-type AlN layer 42 having a film thickness of 4 μm and a Si concentration of 1 × 10 ¹⁷ cm ⁻³ is epitaxially grown on the n-type AlN (0001) substrate 41 by MOCVD. (2) A Schottky electrode (Pd / Au) 43 is formed on the Si-doped n-type AlN layer 42. (3) An ohmic electrode (Ti / Al / Ti / Au) 44 is formed on the back surface of the n-type AlN (0001) substrate 41.

  Although the n-type AlN (0001) substrate 41 is used here, the growth surface of the Si-doped n-type AlN layer 42 is a (0001) plane even if an n-type SiC (0001) substrate is used.

FIG. 11 shows a vertical Schottky diode using Si-doped n-type AlN according to Example 2-2. (D) The growth surface is the (000-1) plane (in this specification, as shown in FIGS. 10 and 11, the code of the superscript bar is represented by “−1” as “1”). This is a Schottky diode using an n-type AlN substrate. The manufacturing process is as follows: (1) a Si-doped n-type AlN layer 52 having a film thickness of 4 μm and a Si concentration of 1 × 10 ¹⁷ cm ⁻³ is formed on the AlN (000-1) substrate 51 by MOCVD; A high-concentration Si-doped n-type AlN layer 53 having a thickness of 10 nm and a Si concentration of 5 × 10 ¹⁹ cm ⁻³ is epitaxially grown. (2) An ohmic electrode (Ti / Al / Ti / Au) 54 is formed on the high-concentration Si-doped n-type AlN layer 53. (3) A Schottky electrode (Pd / Au) 55 is formed on the back surface of the n-type AlN (000-1) substrate 51.

  Although the n-type AlN (000-1) substrate 51 is used here, the growth surface of the Si-doped n-type AlN layer 52 is (000-1) plane even when the n-type SiC (000-1) substrate is used. Become.

  FIG. 12 shows current-voltage characteristics of the vertical Schottky diode of Example 2. (C) is a Schottky diode using an n-type AlN substrate whose growth surface is the (0001) plane, and (D) is a shot using an n-type AlN substrate whose growth surface is the (000-1) plane. (X) of the key diode is a current-voltage characteristic of a Schottky diode manufactured using conventional GaN. The withstand voltage of the conventional Schottky diode is about 90V. In Example 2, the breakdown voltage of the Schottky diode using the (C) n-type AlN substrate whose growth surface is the (0001) plane is 1000 V, and (D) the n-type AlN substrate whose growth surface is the (000-1) plane. The withstand voltage of the Schottky diode using is 900V. Compared with the prior art, the breakdown voltage of the Schottky diode can be increased about 10 times.

  Although an n-type AlN (0001) substrate or an n-type AlN (000-1) substrate is used here, an n-type SiC (0001) substrate or an n-type SiC (000-1) substrate may be used instead. Good. However, although the breakdown voltage is reduced by about 20%, a sufficiently high breakdown voltage Schottky diode can be manufactured as compared with the conventional Schottky diode.

FIG. 13 shows a field effect transistor using a Si-doped n-type AlN layer according to Example 3. Here, a procedure for manufacturing a field effect transistor is shown in the same manner as the method of manufacturing by etching (A) shown in FIG. (1) An undoped AlN layer 62 having a film thickness of 1.0 μm, a film thickness of 1.0 μm, and a Si concentration of 1 × 10 ¹⁸ cm ⁻³ are formed on an AlN (0001) substrate 61 that is a semi-insulating substrate by MOCVD. An Si-doped n-type AlN layer 63 and a high-concentration Si-doped n-type AlN layer 64 having a thickness of 3 nm and an Si concentration of 5 × 10 ¹⁹ cm ⁻³ are epitaxially grown. (2) A drain electrode 65 and a source electrode 67 (Ti / Al / Ti / Au) are formed on the high-concentration Si-doped n-type AlN layer 64.

  (3) A part of the high-concentration Si-doped n-type AlN layer 64 is removed by dry etching (reactive ion etching) using chlorine gas until the Si-doped n-type AlN layer 63 is exposed. (4) A gate electrode 66 (Pd / Au) is formed on the exposed Si-doped n-type AlN layer 63.

  Note that a field-effect transistor can be manufactured similarly to the method of manufacturing by (B) regrowth shown in FIG.

  A field effect transistor using a Si-doped n-type AlN layer according to Example 3, which is (A) a field effect transistor manufactured by a technique using etching, and (B) a field effect transistor manufactured by a technique using regrowth. Table 2 shows the characteristics of a heterostructure field effect transistor fabricated using conventional GaN.

  The conventional field effect transistor has a maximum operating voltage of about 80V. In Example 3, the maximum operating voltage of the field effect transistor manufactured by the method using (A) etching is 700V, and the maximum operating voltage of the field effect transistor manufactured by the method using regrowth is 720V. Compared with the prior art, the operating voltage of the field effect transistor can be increased by about 9 times.

(Production of field effect transistor)
FIG. 14 shows a field effect transistor according to Example 4-1. Here, a procedure for producing (E) an AlN / AlGaN / AlN field-effect transistor is shown in the same manner as in the method of producing by (B) regrowth shown in FIG. (1) An undoped AlN layer 72 having a film thickness of 1 μm, a Si-doped n-type AlN layer 73 having a film thickness of 0.5 μm, and an Si concentration of 1 × 10 ¹⁸ cm ⁻³ are formed on an AlN (0001) substrate 71 by MOCVD. Then, an Al _X Ga _1-X N channel layer 78 having an Al composition X = 0.8 and a film thickness of 30 nm and an AlN cap layer 79 having a film thickness of 5 nm are epitaxially grown. (2) A SiO ₂ mask is deposited by sputtering. (3) A high-concentration Si-doped n-type AlN layer 74 having a film thickness of 40 nm and a Si concentration of 5 × 10 ¹⁹ cm ⁻³ is regrown by MOCVD.

(4) The SiO ₂ mask and the high-concentration Si-doped n-type AlN layer 74 on the SiO ₂ mask are removed by lift-off. (5) A drain electrode 75 and a source electrode 77 (Ti / Al / Ti / Au) are formed on the high-concentration Si-doped n-type AlN layer 74 formed by regrowth. (6) A gate electrode 76 (Pd / Au) is formed on the AlN cap layer 79.

FIG. 15 shows a field effect transistor according to Example 4-2. (F) An AlN / AlGaN / AlN field effect transistor is fabricated by etching and regrowth. In the field effect transistor, an undoped AlN layer 82 and a Si-doped n-type AlN layer 83 are sequentially stacked on an AlN (0001) substrate 81. Furthermore, an Al _X Ga _1-X N channel layer 88 and an AlN cap layer 89 are stacked on the Si-doped n-type AlN layer 83. A high-concentration Si-doped n-type Al _Y Ga ₁ -YN layer 84 is formed in a portion where the AlN cap layer 89 and the Al _X Ga _1-X N channel layer 88 are partially removed, and a high-concentration Si-doped n-type Al type Al _A drain electrode 85 and a source electrode 87 (Ti / Al / Ti / Au) are formed on the _Y Ga _1-Y N layer 84. On the remaining portion of the AlN cap layer 89, a gate electrode 86 (Pd / Au) is formed.

FIG. 16 shows a method of manufacturing the field effect transistor according to Example 4-2. (FIG. 16A) By MOCVD, an undoped AlN layer 82 having a film thickness of 1 μm and a Si-doped n-type film having a film thickness of 0.5 μm and a Si concentration of 1 × 10 ¹⁸ cm ⁻³ are formed on an AlN (0001) substrate 81. An AlN layer 83, an Al _X Ga _1-X N channel layer 88 with an Al composition X = 0.8 and a thickness of 30 nm, and an AlN cap layer 89 with a thickness of 5 nm are epitaxially grown. (FIG. 16B) A SiO ₂ mask 90 is deposited by sputtering. (FIG. 16 (c)) a portion of the AlN cap layer 89 and the _{Al X Ga 1-X} N channel layer _88, until the Al _{X Ga 1-X} N-channel layer 88 is exposed, dry etching using a chlorine gas ( Reactive ion etching).

(FIG. 16 (d)) A high-concentration Si-doped n-type Al _Y Ga _1-Y N layer 84 having an Al composition Y = 0.75, a film thickness of 40 nm, and an Si concentration of 5 × 10 ¹⁹ cm ⁻³ is obtained again by MOCVD. Grow. (FIG. 16E) The SiO ₂ mask 90 and the high-concentration Si-doped n-type Al _Y Ga _1-Y N layer 84 on the SiO ₂ mask 90 are removed by lift-off. (FIG. 16F) A drain electrode 85 and a source electrode 87 are formed on the high-concentration Si-doped n-type Al _Y Ga _1-Y N layer 84 formed by regrowth. (FIG. 16G) A gate electrode 86 is formed on the AlN cap layer 89.

  Note that a field-effect transistor can be manufactured similarly to the method of manufacturing by (B) regrowth shown in FIG.

  (E) AlN / AlGaN / AlN field effect transistor fabricated by regrowth, (F) Heterostructure field effect fabricated using conventional GaN, AlN / AlGaN / AlN field effect transistor fabricated by etching and regrowth Table 3 shows the characteristics of the transistor.

  The conventional field effect transistor has a maximum operating voltage of about 80V. In Example 4, the maximum operating voltage of a field effect transistor manufactured by (E) regrowth is 600V, and the maximum operating voltage of a field effect transistor manufactured by using (F) etching and regrowth is 600V. Compared with the prior art, the operating voltage of the field effect transistor can be increased by about 7.5 times. Further, the maximum mutual contactance of the AlN / AlGaN / AlN field effect transistor is as high as 800 mS / mm and the maximum drain current is 2 A / mm or more. Thus, by sandwiching the AlGaN channel layer between the AlN cap layer and the Si-doped n-type AlN layer, a field effect transistor with extremely excellent high output characteristics can be produced.

(Channel thickness and Al composition)
FIG. 17 shows the relationship between the Al _X Ga _1-X N channel layer thickness and the Al composition X of the AlN / Al _X Ga _1-X N / AlN field effect transistor. In Example 4, the Al _X Ga _1-X N channel layers 78 and 88 had an Al composition X of 0.8 and a film thickness of 30 nm. The conditions for obtaining a field effect transistor excellent in high output characteristics, such as a maximum operating voltage of 100 V or more, a maximum mutual contactance of 500 mS / mm or more, and a maximum drain current of 1 A / mm or more, are given. Show.

When the Al composition X of the Al _X Ga _1-X N channel layers 78 and 88 exceeds 0.9, excellent characteristics cannot be obtained at any film thickness. When the Al composition X is 0.9, the film thickness is 200 nm or less, when the Al composition X is 0.7, the film thickness is 150 nm or less, when the Al composition X is 0.5, the film thickness is 100 nm or less, and when the Al composition X is 0.2, When the film thickness is 50 nm or less and the Al composition X is 0, excellent characteristics can be obtained only when the film thickness is 20 nm or less. When the film thickness of the Al _X Ga _1-X N channel layers 78 and 88 is t (nm), when the Al composition X is 0.9 or less,
t <20 + 200 × X,
Only under these conditions, a field effect transistor having excellent high output characteristics can be obtained.

Further, in relation to the Al composition Y of the high-concentration Si-doped n-type Al _Y Ga _1-Y N layer 84, it is preferable that Y ≦ X. The contact resistance between the gate electrode 86 and the source electrode 87 can be reduced, and a high-power electronic device with extremely low power loss can be manufactured by reducing the element resistance.

(Si concentration and drain current)
FIG. 18 shows the relationship between the Si concentration of the Si-doped n-type AlN layer and the maximum drain current. In Example 4, the Si concentration of the Si-doped n-type AlN layers 73 and 83 was 1 × 10 ¹⁸ cm ⁻³ . The maximum drain current of 1 A / mm or more is obtained only when the Si concentration is in the range of 5 × 10 ¹⁶ cm ⁻³ to 5 × 10 ¹⁸ cm ⁻³ . However, the field effect transistor does not operate at 5 × 10 ¹⁶ cm ⁻³ or less. This is because n-type AlN having high conductivity cannot be obtained when the Si concentration is 5 × 10 ¹⁶ cm ⁻³ or less. Therefore, a field effect transistor having a high maximum drain current is produced by setting the Si concentration of the Si-doped n-type AlN layers 73 and 83 to a range of 5 × 10 ¹⁶ cm ⁻³ to 5 × 10 ¹⁸ cm ^−3. Can do.

(Cap thickness and gm)
FIG. 19 shows the relationship between the film thickness of the AlN cap layer and the maximum transconductance. In Example 4, the thickness of the AlN cap layers 79 and 89 was 5 nm. The maximum mutual contactance of 500 mS / mm or more is obtained only when the thickness of the AlN cap layers 79 and 89 is 15 nm or less. At a film thickness of 3 nm, the maximum mutual contactance increases to 900 mS / mm. Since the AlN cap layers 79 and 89 are grown by the MOCVD method, the film thickness of the AlN cap layers 79 and 89 can be controlled with an accuracy of 0.5 nm. Therefore, by setting the thickness of the AlN cap layer to 15 nm or less, it is possible to produce a field effect transistor having a high maximum mutual contactance.

(Production of field effect transistor)
FIG. 20 shows an AlN / Si / AlN field effect transistor according to Example 5-1. (G) Shows the structure of an AlN / Si / AlN field effect transistor fabricated by etching and regrowth. Here, a procedure for manufacturing a field effect transistor is shown in the same manner as the procedure of Example 4-2 shown in FIG. (1) An undoped AlN layer 102 having a thickness of 1 μm, a Si layer 103 having a molecular layer of 0.1, and an AlN cap layer 109 having a thickness of 8 nm are epitaxially grown on an AlN (0001) substrate 101 by MOCVD. (2) A SiO ₂ mask is deposited by sputtering. (3) The AlN cap layer 109 and part of the Si layer 103 are removed by dry etching (reactive ion etching) using chlorine gas until the undoped AlN layer 102 is exposed.

(4) The high-concentration Si-doped n-type AlN layer 104 having a film thickness of 40 nm and a Si concentration of 5 × 10 ¹⁹ cm ⁻³ is regrown by MOCVD. (5) The SiO ₂ mask is removed by lift-off. (6) A drain electrode 105 and a source electrode 107 (Ti / Al / Ti / Au) are formed on the high-concentration Si-doped n-type AlN layer 104 formed by regrowth. (7) A gate electrode 106 (Pd / Au) is formed on the AlN cap layer 109.

FIG. 21 shows an AlN / Si / AlN field effect transistor according to Example 5-2. (H) Shows the structure of an AlN / Si / AlN field effect transistor fabricated by regrowth. Here, a procedure for manufacturing a field effect transistor is shown in the same manner as the procedure of the first embodiment shown in FIG. (1) An undoped AlN layer 112 having a thickness of 1 μm, a Si layer 113 having a thickness of 0.1 molecular layer, and an AlN cap layer 119 having a thickness of 8 nm are epitaxially grown on an AlN (0001) substrate 111 by MOCVD. (2) A SiO ₂ mask is deposited by sputtering. (3) A high-concentration Si-doped n-type AlN layer 114 having a film thickness of 40 nm and a Si concentration of 5 × 10 ¹⁹ cm ⁻³ is regrown by MOCVD.

(4) The SiO ₂ mask and the high-concentration Si-doped n-type AlN layer 114 on the SiO ₂ mask are removed by lift-off. (5) A drain electrode 115 and a source electrode 117 (Ti / Al / Ti / Au) are formed on the high-concentration Si-doped n-type AlN layer 114 formed by regrowth. (6) A gate electrode 116 (Pd / Au) is formed on the AlN cap layer 119.

  (G) AlN / Si / AlN field effect transistor fabricated by etching and regrowth, (H) AlN / Si / AlN field effect transistor fabricated by regrowth, and heterostructure field effect fabricated using conventional GaN Table 4 shows the characteristics of the transistor.

  The conventional field effect transistor has a maximum operating voltage of about 80V. In Example 5, the maximum operating voltage of an AlN / Si / AlN field effect transistor fabricated by (G) etching and regrowth is 560 V, and (H) the maximum operating voltage of an AlN / Si / AlN field effect transistor fabricated by regrowth. Is 550V. Compared with the prior art, the operating voltage of the field effect transistor can be increased about 7 times.

(Si film thickness)
FIG. 22 shows the relationship between the deposition amount of the Si layer and the maximum drain current. As described above, in Example 5, the deposition amount of the Si layers 103 and 113 was 0.1 molecular layer. The maximum drain current of 0.5 A / mm or more can be obtained only when the deposition amount of the Si layers 103 and 113 is one molecular layer or less. However, when no Si layer is inserted, the field effect transistor does not operate. Therefore, a field effect transistor having a high maximum drain current can be manufactured by setting the deposition amount of the Si layers 103 and 113 to one molecular layer or less.

  As described above, Pd / Au is used for the Schottky electrode of the Schottky diode and the gate electrode of the field effect transistor. These electrodes are required to have Schottky characteristics having a high breakdown voltage. Table 5 shows the results of examining the relationship between the materials used for these electrodes and the withstand voltage.

  The Schottky diode of Example 1 shown in FIG. 3 was produced and the breakdown voltage was measured. Pd, Pt, Ni, Au, Mo, W, Ta, Nb, Al, Ti, Mg, and In were investigated as metal materials used for the Schottky electrode. A high breakdown voltage of 500 V or more can be obtained only with Pd, Pt, Ni, Au, Mo, W, Ta, Nb, Al, and Ti. Even when another electrode is laminated on these electrodes, the surface of the Si-doped n-type AlN layer or AlN cap layer and Pd, Pt, Ni, Au, Mo, W, Ta, Nb, Al, and Ti If at least one of them is in contact, a high breakdown voltage can be obtained.

(Structure to form electrodes)
As described above, the ohmic electrode of the Schottky diode and the source electrode and drain electrode of the field effect transistor were formed on the high-concentration Si-doped n-type AlN layer. These electrodes are required to have ohmic characteristics having a low contact resistance. The relationship between the structure forming the ohmic electrode and the contact resistance of the ohmic electrode was investigated. The contact resistance was determined using the transmission line (TLM) method. The following four structures were produced.

(A) A structure in which an undoped AlN layer (film thickness 0.5 μm) and a Si-doped n-type AlN layer (film thickness 4 μm, Si concentration 1 × 10 ¹⁷ cm ⁻³ ) are epitaxially grown on an AlN (0001) substrate. Here, a high-concentration Si-doped n-type AlN layer is not used.
(B) Undoped AlN layer (film thickness 0.5 μm), Si-doped n-type AlN layer (film thickness 4 μm, Si concentration 1 × 10 ¹⁷ cm ⁻³ ), high-concentration Si-doped n-type AlN on AlN (0001) substrate A structure obtained by epitaxially growing a layer (film thickness: 10 nm, Si concentration: 5 × 10 ¹⁹ cm ⁻³ ).
(C) Undoped AlN layer (film thickness 0.5 μm), Si-doped n-type AlN layer (film thickness 4 μm, Si concentration 1 × 10 ¹⁷ cm ⁻³ ), high-concentration Si-doped n-type AlN on AlN (0001) substrate Layer (film thickness 3 nm, Si concentration 5 × 10 ¹⁹ cm ⁻³ ), high-concentration Si-doped n-type Al _Z Ga _1-Z N composition gradient layer (Al composition Z continuously changed from 1 to 0, film thickness 3 nm, Si concentration 5 × 10 ¹⁹ cm ⁻³ ), a structure in which a high concentration Si-doped n-type GaN layer (film thickness 3 nm, Si concentration 5 × 10 ¹⁹ cm ⁻³ ) is epitaxially grown.
(D) Undoped AlN layer (film thickness 0.5 μm), Si-doped n-type AlN layer (film thickness 4 μm, Si concentration 1 × 10 ¹⁷ cm ⁻³ ), high-concentration Si-doped n-type AlN on AlN (0001) substrate Layer (film thickness 3 nm, Si concentration 5 × 10 ¹⁹ cm ⁻³ ), high-concentration Si-doped n-type AlN layer (film thickness 3 nm, Si concentration 5 × 10 ¹⁹ cm ⁻³ ) and high-concentration Si-doped n-type Al _Z Ga A structure in which a superlattice layer (5 periods) in which _1-ZN layers (thickness 3 nm, Al composition Z = 0.2, Si concentration 5 × 10 ¹⁹ cm ⁻³ ) are alternately stacked is epitaxially grown.

  Table 6 shows the contact resistance of the ohmic electrode obtained in the structures of (A) to (D).

  The lower the contact resistance, the higher frequency operation is possible and the loss can be reduced. When (A) and (B) are compared, the contact resistance can be greatly reduced to 1/500 or less by inserting a high-concentration Si-doped AlN layer between the Si-doped n-type AlN layer and the ohmic electrode. I understand. Therefore, the structure using the high-concentration Si-doped AlN layer can increase the frequency and the loss of the high-power electronic device.

Compared (B) and the (C), a high concentration Si-doped n-type AlN layer, higher concentrations Si-doped n-type _{Al Z Ga 1-Z} N composition gradient layer, the high-concentration Si-doped n-type GaN layer It can be seen that the contact resistance can be lowered by the insertion. Compared (B) and the (D), a high concentration Si-doped n-type AlN layer, by inserting a heavily doped _{AlN / Al Z Ga 1-Z} N superlattice layer, can be lowered contact resistance Recognize.

(Type of electrode)
As described above, Ti / Al / Ti / Au is used for the ohmic electrode of the Schottky diode and the source electrode and drain electrode of the field effect transistor. These electrodes are required to have low contact resistance. Table 7 shows the results of examining the relationship between the materials used for these electrodes and the contact resistance.

The structure of Example 7 (B) described above was prepared, and the contact resistance was measured by the TLM method. As metal materials used for these electrodes, Pd, Pt, Ni, Au, Mo, W, Ta, Nb, Al, Ti, Mg, and In were examined. 10 ^-5 [Omega] cm ² units very low contact resistance is, Mo, W, Ta, Al , obtained only Ti. Further, even when another metal is laminated on these metals, a low contact resistance can be obtained similarly.

It is sectional drawing which shows the conventional Schottky diode using GaN. It is sectional drawing which shows the conventional GaN-type heterostructure field effect transistor. 3 is a diagram illustrating a Schottky diode using a Si-doped n-type AlN layer according to Example 1. FIG. It is a figure which shows the method of producing the Schottky diode of Example 1 by an etching. It is a figure which shows the method of producing the Schottky diode of Example 1 by regrowth. FIG. 3 is a diagram showing current-voltage characteristics of the Schottky diode of Example 1. It is a figure which shows the relationship between Si density | concentration of a Si dope n-type AlN layer, and a proof pressure. It is a figure which shows the relationship between Si density | concentration of a high concentration Si dope n-type AlN layer, and contact resistance. Can be removed by lift-off is a diagram showing the relationship between the thickness and the Al composition of the high concentration Si-doped n-type _Al Y _{Ga 1-Y} N layer. It is sectional drawing which shows the vertical Schottky diode using Si dope n type AlN concerning Example 2-1. It is sectional drawing which shows the vertical Schottky diode using Si dope n-type AlN concerning Example 2-2. 6 is a diagram showing current-voltage characteristics of a vertical Schottky diode of Example 2. FIG. 6 is a diagram showing a field effect transistor using a Si-doped n-type AlN layer according to Example 3. FIG. It is sectional drawing which shows the field effect transistor concerning Example 4-1. It is sectional drawing which shows the field effect transistor concerning Example 4-2. It is a figure which shows the method of producing the field effect transistor concerning Example 4-2. Is a diagram showing the relationship between the _{AlN / Al X Ga 1-X} N / AlN field effect transistor _{Al X Ga 1-X} N film thickness of the channel layer and the Al composition X. It is a figure which shows the relationship between Si density | concentration of Si dope n-type AlN layer, and maximum drain current. It is a figure which shows the relationship between the film thickness of an AlN cap layer, and maximum transconductance. It is sectional drawing which shows the AlN / Si / AlN field effect transistor concerning Example 5-1. It is sectional drawing which shows the AlN / Si / AlN field effect transistor concerning Example 5-2. It is a figure which shows the relationship between the deposition amount of Si layer, and the maximum drain current.

Explanation of symbols

11 n-type GaN substrate 12 Si-doped n-type GaN layer 13, 35, 43, 54 Schottky electrode 14, 36, 44, 55 Ohmic electrode 21 substrate 22 undoped GaN layer 23 Si-doped AlGaN cap layer 24, 67, 77, 87 107, 117 Source electrode 25, 66, 76, 86, 106, 116 Gate electrode 26, 65, 75, 85, 105, 115 Drain electrode 31, 41, 61, 71, 81, 101, 111 AlN (0001) substrate 32, 62, 72, 82, 102, 112 Undoped AlN layer 33, 42, 52, 63, 73, 83 Si-doped n-type AlN layer 34, 53, 64, 74, 84, 104, 114 High-concentration Si-doped n-type AlN layer 37,90 SiO ₂ mask 51 AlN (000-1) substrate 78,88 Al _X Ga _1-X N channel layer 79, 89, 109, 119 AlN cap layer 103, 113 Si layer

Claims (29)

An undoped AlN layer stacked on a semi-insulating substrate;
A Si-doped n-type AlN layer stacked on the undoped AlN layer;
An ohmic electrode formed on the Si-doped n-type AlN layer via a high-concentration Si-doped n-type AlN layer;
A Schottky electrode formed on the Si-doped n-type AlN layer,
The Si concentration of the Si-doped n-type AlN layer is 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ , and the Si concentration of the high-concentration Si-doped n-type AlN layer is 5 × 10 ¹⁹ cm ⁻ A Schottky diode characterized by being ³ or more. A substrate made of any one of n-type AlN and n-type SiC whose growth surface is a (0001) plane;
A Si-doped n-type AlN layer stacked on the substrate and having a Si concentration of 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ ;
A Schottky electrode formed on the Si-doped n-type AlN layer;
An Schottky diode comprising: an ohmic electrode formed on the back surface of the substrate. A substrate made of any material of n-type AlN and n-type SiC whose growth surface is a (000-1) plane;
A Si-doped n-type AlN layer laminated on the substrate;
A high-concentration Si-doped n-type AlN layer stacked on the Si-doped n-type AlN layer;
An ohmic electrode formed on the high-concentration Si-doped n-type AlN layer;
A Schottky electrode formed on the back surface of the substrate,
The Si concentration of the Si-doped n-type AlN layer is 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ , and the Si concentration of the high-concentration Si-doped n-type AlN layer is 5 × 10 ¹⁹ cm ⁻ A Schottky diode characterized by being ³ or more. Said high during concentration Si-doped n-type AlN layer and said ohmic electrode, formed a high-concentration Si-doped n-type _{Al Z Ga 1-Z} N composition gradient layer, and a high-concentration Si-doped n-type GaN layer, wherein the high concentration Si-doped n-type _Al Z _{Ga 1-Z} n Al composition Z of the composition gradient layer, continuous to the high concentration Si-doped n-type GaN layer 1 toward 0 from the high concentration Si-doped n-type AlN layer to alter, wherein the Si concentration of the high concentration Si-doped n-type _{Al Z Ga 1-Z} n composition gradient layer and the high concentration Si-doped n-type GaN layer is 1 × ¹⁰ 19 ^{cm -3} or more The shot diode according to claim 1 or 3. It said high during concentration Si-doped n-type AlN layer and the ohmic electrode, the high-concentration Si-doped n-type AlN layer and the high-concentration Si-doped n-type _{Al Z Ga 1-Z} N layer and the superlattice layer formed by alternately laminating forming a said high concentration Si-doped n-type _Al Z _{Ga 1-Z} n layer of Al composition Z is 0 to 0.9, the high concentration Si-doped n-type AlN layer and the high concentration Si-doped n-type the film thickness of the Al _Z Ga _1-Z n layer is 5nm or less, Si concentration of the high concentration Si-doped n-type AlN layer and the high concentration Si-doped n-type _{Al Z Ga 1-Z} n layer is 1 × The Schottky diode according to claim 1, wherein the Schottky diode is 10 ¹⁹ cm ⁻³ or more. The ohmic electrode includes any one of Mo, W, Ta, Al, Ti,
The surface of the high-concentration Si-doped n-type AlN layer, the high-concentration Si-doped n-type GaN layer, or the superlattice layer is in contact with any one material of Ti, Al, W, Mo, and Ta. The Schottky diode according to any one of claims 1 and 3 to 5. The Schottky electrode includes any one of Pd, Pt, Ni, Au, Mo, W, Ta, Nb, Al, Ti,
3. The surface of the Si-doped n-type AlN layer is in contact with any one material of Pd, Pt, Ni, Au, Mo, W, Ta, Nb, Al, and Ti. A Schottky diode described in 1.   2. The Schottky diode according to claim 1, wherein the semi-insulating substrate is any one of an AlN substrate, a SiC substrate, and a sapphire substrate whose growth surface is a (0001) plane. An undoped AlN layer stacked on a semi-insulating substrate;
A Si-doped n-type AlN layer stacked on the undoped AlN layer;
A drain electrode and a source electrode formed on the Si-doped n-type AlN layer via a high-concentration Si-doped n-type AlN layer;
A gate electrode formed on the Si-doped n-type AlN layer,
The Si concentration of the Si-doped n-type AlN layer is 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ , and the Si concentration of the high-concentration Si-doped n-type AlN layer is 5 × 10 ¹⁹ cm ^{− 3.} A field effect transistor characterized by being ³ or more. An undoped AlN layer stacked on a semi-insulating substrate;
A Si-doped n-type AlN layer stacked on the undoped AlN layer;
An Al _X Ga _1-X N channel layer stacked on the Si-doped n-type AlN layer;
An AlN cap layer stacked on the Al _X Ga _1-X N channel layer;
A drain electrode and a source electrode formed on the AlN cap layer via a high-concentration Si-doped n-type AlN layer;
A gate electrode formed on the AlN cap layer,
The Si concentration of the Si-doped n-type AlN layer is 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ , and the Al composition X of the Al _X Ga _1-X N channel layer is 0.9 or less. The film thickness t (nm) of the Al _X Ga _1-X N channel layer satisfies the relationship of t <20 + 200 × X, and the Si concentration of the high-concentration Si-doped n-type AlN layer is 5 × 10 ¹⁹ A field-effect transistor characterized by being cm ⁻³ or more. An undoped AlN layer stacked on a semi-insulating substrate;
A Si-doped n-type AlN layer stacked on the undoped AlN layer;
An Al _X Ga _1-X N channel layer stacked on the Si-doped n-type AlN layer;
An AlN cap layer stacked on the Al _X Ga _1-X N channel layer;
A drain electrode and a source electrode formed on the portion from which the AlN cap layer and a part of the Al _X Ga _1-X N channel layer have been removed via a high-concentration Si-doped n-type Al _Y Ga _1-Y N layer; ,
A gate electrode formed on the AlN cap layer,
The Si concentration of the Si-doped n-type AlN layer is 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ , and the Al composition X of the Al _X Ga _1-X N channel layer is 0.9 or less. The film thickness t (nm) of the Al _X Ga _1-X N channel layer satisfies the relationship of t <20 + 200 × X, and the Si concentration of the high-concentration Si-doped n-type Al _Y Ga _1-Y N layer Is 5 × 10 ¹⁹ cm ⁻³ or more, and the relationship between the Al composition X and Y is Y ≦ X. An undoped AlN layer stacked on a semi-insulating substrate;
A Si layer laminated on the undoped AlN layer and having a film thickness of one molecular layer or less;
An AlN cap layer having a film thickness of 15 nm or less laminated on the Si layer;
A drain electrode and a source electrode formed via a high-concentration Si-doped n-type AlN layer on a part of the AlN cap layer, the Si layer, and the undoped AlN layer removed, and
A gate electrode formed on the AlN cap layer,
The field effect transistor according to claim 1, wherein the Si concentration of the high-concentration Si-doped n-type AlN layer is 1 × 10 ¹⁹ cm ⁻³ or more. An undoped AlN layer stacked on a semi-insulating substrate;
A Si layer laminated on the undoped AlN layer and having a film thickness of one molecular layer or less;
An AlN cap layer having a film thickness of 15 nm or less laminated on the Si layer;
A drain electrode and a source electrode formed on the AlN cap layer via a high-concentration Si-doped n-type AlN layer;
A gate electrode formed on the AlN cap layer,
The field effect transistor according to claim 1, wherein the Si concentration of the high-concentration Si-doped n-type AlN layer is 1 × 10 ¹⁹ cm ⁻³ or more. Between the drain electrode and the source electrode and the high concentration Si-doped n-type AlN layer, forming a high-concentration Si-doped n-type _{Al Z Ga 1-Z} N composition gradient layer, and a high-concentration Si-doped n-type GaN layer and, the high concentration Si-doped n-type _Al Z _{Ga 1-Z} n Al composition Z of the composition gradient layer, from 1 toward the high-concentration Si-doped n-type GaN layer from the high concentration Si-doped n-type AlN layer 0 continuously changed to, Si concentration of the high concentration Si-doped n-type _{Al Z Ga 1-Z} n composition gradient layer and the high concentration Si-doped n-type GaN layer is a 1 × ¹⁰ 19 ^{cm -3} or more 14. The field effect transistor according to claim 9, wherein Between the drain electrode and the source electrode and the high concentration Si-doped n-type AlN layer, by laminating a high concentration Si-doped n-type AlN layer and the high-concentration Si-doped n-type _{Al Z Ga 1-Z} N layer are alternately forming a superlattice layer, the high concentration Si-doped n-type _Al Z _{Ga 1-Z} n layer of Al composition Z is 0 to 0.9, the high concentration Si-doped n-type AlN layer and the high-concentration Si thickness of doped n-type _{Al Z Ga 1-Z} n layer is 5nm or less, Si concentration of the serial high-concentration Si-doped n-type AlN layer and the high concentration Si-doped n-type _{Al Z Ga 1-Z} n layer The field effect transistor according to claim 9, wherein the field effect transistor is 1 × 10 ¹⁹ cm ⁻³ or more. The drain electrode and the source electrode include any one of Mo, W, Ta, Al, Ti,
The surface of the high-concentration Si-doped n-type AlN layer, the high-concentration Si-doped n-type Al _Y Ga _1-YN layer, the high-concentration Si-doped n-type GaN layer or the superlattice layer and Ti, Al, W, Mo 16. The field effect transistor according to claim 9, wherein any one material of Ta and Ta is in contact. The material of the gate electrode includes any one of Pd, Pt, Ni, Au, Mo, W, Ta, Nb, Al, Ti,
The surface of the Si-doped n-type AlN layer or the AlN cap layer is in contact with any one material of Pd, Pt, Ni, Au, Mo, W, Ta, Nb, Al, and Ti. The field effect transistor according to claim 9.   14. The field effect transistor according to claim 9, wherein the semi-insulating substrate is any one of an AlN substrate, a SiC substrate, and a sapphire substrate whose growth surface is a (0001) plane. An undoped AlN layer is laminated on a semi-insulating substrate, and an Si-doped n-type AlN layer having a Si concentration of 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ is laminated on the undoped AlN layer, A first step of laminating a high-concentration Si-doped n-type AlN layer having a Si concentration of 1 × 10 ¹⁹ cm ⁻³ or more on the Si-doped n-type AlN layer;
A second step of removing a portion of the high-concentration Si-doped n-type AlN layer by etching until the Si-doped n-type AlN layer is exposed;
Forming a Schottky electrode on the exposed Si-doped n-type AlN layer;
And a fourth step of forming an ohmic electrode on the high-concentration Si-doped n-type AlN layer. An undoped AlN layer is stacked on a semi-insulating substrate, and a Si-doped n-type AlN layer having a Si concentration of 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ is stacked on the undoped AlN layer. 1 process,
A second step of selectively forming a high-concentration Si-doped n-type AlN layer having a Si concentration of 1 × 10 ¹⁹ cm ⁻³ or more on the Si-doped n-type AlN layer by regrowth;
A third step of forming a Schottky electrode on the Si-doped n-type AlN layer;
And a fourth step of forming an ohmic electrode on the high-concentration Si-doped n-type AlN layer formed by regrowth. A method for manufacturing a Schottky diode, comprising: Si-doped n-type having a Si concentration of 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ on a substrate made of any material of n-type AlN and n-type SiC whose growth surface is the (0001) plane. A first step of epitaxially growing an AlN layer;
A second step of forming a Schottky electrode on the Si-doped n-type AlN layer;
And a third step of forming an ohmic electrode on the back surface of the substrate. A Si-doped n-type AlN layer is laminated on a substrate made of either n-type AlN or n-type SiC whose growth surface is a (000-1) plane, and the Si concentration is 1 × 10 ¹⁹ cm ⁻³ or more. A first step of laminating a high concentration Si-doped n-type AlN layer on the Si-doped n-type AlN layer;
A second step of forming an ohmic electrode on the high-concentration Si-doped n-type AlN layer;
And a third step of forming a Schottky electrode on the back surface of the substrate. An undoped AlN layer is laminated on a semi-insulating substrate, and an Si-doped n-type AlN layer having a Si concentration of 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ is laminated on the undoped AlN layer, A first step of laminating a high-concentration Si-doped n-type AlN layer having a Si concentration of 1 × 10 ¹⁹ cm ⁻³ or more on the Si-doped n-type AlN layer;
A second step of removing a part of the high-concentration Si-doped n-type AlN layer by etching until the Si-doped n-type AlN layer is exposed;
A third step of forming a gate electrode on the exposed Si-doped n-type AlN layer;
And a fourth step of forming a source electrode and a drain electrode on the high-concentration Si-doped n-type AlN layer. An undoped AlN layer is stacked on a semi-insulating substrate, and a Si-doped n-type AlN layer having a Si concentration of 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ is stacked on the undoped AlN layer. 1 process,
A second step of selectively forming a high-concentration Si-doped n-type AlN layer having a Si concentration of 1 × 10 ¹⁹ cm ⁻³ or more on the Si-doped n-type AlN layer by regrowth;
A third step of forming a gate electrode on the Si-doped n-type AlN layer;
And a fourth step of forming a source electrode and a drain electrode on the high-concentration Si-doped n-type AlN layer formed by regrowth. A method for producing a field effect transistor, comprising: An undoped AlN layer is laminated on a semi-insulating substrate, and an Si-doped n-type AlN layer having a Si concentration of 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ is laminated on the undoped AlN layer, An Al _X Ga _1-X N channel layer satisfying a relationship of Al composition X of 0.9 or less and a film thickness t (nm) of t <20 + 200 × X is stacked on the Si-doped n-type AlN layer; An AlN cap layer having a film thickness of 15 nm or less is stacked on the Al _X Ga _1-X N channel layer, the Al composition Y satisfies the relationship of Al composition X and Y ≦ X, and the Si concentration is 1 × 10 ¹⁹ cm. ^A first step of stacking a high-concentration Si-doped n-type Al _Y Ga _1-Y N layer that is ⁻³ or more;
A second step of removing a part of the high-concentration Si-doped n-type Al _Y Ga _1-Y N layer by etching until the AlN cap layer is exposed;
A third step of forming a gate electrode on the exposed AlN cap layer;
And a fourth step of forming a source electrode and a drain electrode on the high-concentration Si-doped n-type Al _Y Ga _1-YN layer. An undoped AlN layer is laminated on a semi-insulating substrate, and an Si-doped n-type AlN layer having a Si concentration of 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ is laminated on the undoped AlN layer, An Al _X Ga _1-X N channel layer satisfying a relationship of Al composition X of 0.9 or less and a film thickness t (nm) of t <20 + 200 × X is stacked on the Si-doped n-type AlN layer; A first step of laminating an AlN cap layer having a thickness of 15 nm or less on the Al _X Ga _1-X N channel layer;
A high-concentration Si-doped n-type Al _Y Ga _1-Y N layer having an Al composition Y satisfying the relationship of Al composition X and Y ≦ X and having an Si concentration of 1 × 10 ¹⁹ cm ⁻³ or more on the AlN cap layer A second step of selectively forming by regrowth;
A third step of forming a gate electrode on the AlN cap layer;
And a fourth step of forming a source electrode and a drain electrode on the high-concentration Si-doped n-type Al _Y Ga _1-Y N layer formed by regrowth. A method for producing a field effect transistor, comprising: An undoped AlN layer is laminated on a semi-insulating substrate, and an Si-doped n-type AlN layer having a Si concentration of 5 × 10 ¹⁶ cm ^{−3 to} 5 × 10 ¹⁸ cm ⁻³ is laminated on the undoped AlN layer, An Al _X Ga _1-X N channel layer satisfying a relationship of Al composition X of 0.9 or less and a film thickness t (nm) of t <20 + 200 × X is stacked on the Si-doped n-type AlN layer; A first step of laminating an AlN cap layer having a thickness of 15 nm or less on the Al _X Ga _1-X N channel layer;
A second step of removing a part of the AlN cap layer and the Al _X Ga _1-X N channel layer by etching to the vicinity of the Si-doped n-type AlN layer;
On the exposed Si-doped n-type AlN layer, a high-concentration Si-doped n-type Al _Y Ga in which the Al composition Y satisfies the relationship of Al composition X and Y ≦ X and the Si concentration is 1 × 10 ¹⁹ cm ⁻³ or more. _A third step of selectively forming a _1-YN layer by regrowth;
A fourth step of forming a gate electrode on the AlN cap layer;
And a fifth step of forming a source electrode and a drain electrode on the high-concentration Si-doped n-type Al _Y Ga _1-Y N layer formed by regrowth. An undoped AlN layer is laminated on a semi-insulating substrate, a Si layer having a film thickness of 1 molecular layer or less is laminated on the undoped AlN layer, and an AlN cap layer having a film thickness of 15 nm or less is laminated on the Si layer. A first step;
A second step of selectively forming a high-concentration Si-doped n-type AlN layer having a Si concentration of 1 × 10 ¹⁹ cm ⁻³ or more on the AlN cap layer by regrowth;
A third step of forming a gate electrode on the AlN cap layer;
And a fourth step of forming a source electrode and a drain electrode on the high-concentration Si-doped n-type AlN layer formed by regrowth. A method for producing a field effect transistor, comprising: An undoped AlN layer is laminated on a semi-insulating substrate, a Si layer having a film thickness of 1 molecular layer or less is laminated on the undoped AlN layer, and an AlN cap layer having a film thickness of 15 nm or less is laminated on the Si layer. A first step;
A second step of removing a part of the AlN cap layer, the Si layer, and the undoped AlN layer by etching;
A third step of selectively forming a high-concentration Si-doped n-type AlN layer having a Si concentration of 1 × 10 ¹⁹ cm ⁻³ or more on the exposed undoped AlN layer by regrowth;
A fourth step of forming a gate electrode on the AlN cap layer;
And a fifth step of forming a source electrode and a drain electrode on the high-concentration Si-doped n-type AlN layer formed by regrowth.

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