TW569464B - Light-emitting diode structure having low-resistance layer - Google Patents

Abstract

A light-emitting diode structure is disclosed, which comprises a low-resistance layer structure in the P-type and/or N-type region, which can reduce the equivalent resistance of the P-type and/or N-type region, so as to reduce the operating voltage of the device for increasing the power.

Description

569464 Γ

[Field of the Invention] The present invention relates to a semiconductor element, and in particular, to a diode element with low hole mobility, which can reduce its equivalent resistance. The present invention is particularly suitable for wide energy systems such as gallium nitride [Application background of diode elements, etc.] [Background of the Invention] Due to the development of epitaxial technology, typical optoelectronic elements often grow n-type regions, light-emitting regions, p-type regions, and n-type and p-type regions in order on the substrate. The electrode contact area is made because the electron mobility is higher than the hole mobility, and the effective doping amount of the hole is generally lower than the electron, that is, the P-type resistance is higher than the η-type resistance under the same thickness ^ and structure Generally, the solution is to form a thin and long shape, and grow it at the top of the structure to reduce the resistance. ; ,,,, In the application of hair light monopoles, in order to increase the luminous efficiency, transparent electrodes are a very important choice. On the gallium nitride light emitting diodes, Ni / Au is often evaporated on its ρ region. It can be made transparent by heat treatment to increase penetration. As for the commonly used transparent conductive oxide material, indium tin oxide (in.⑽ tin c ^ ide 'ITO), although it can form ohmic contact with n-type gallium nitride, On P-type gallium nitride, due to work function problems, good ohmic contact cannot be formed, so it cannot be directly applied to gallium nitride elements. In general, an indirect layer can be added between ιτο and ρ-type gallium nitride. (Interlayer) to adjust interface parameters such as work function to form ohmic contact and reduce contact current 1¾. However, this method increases the indirect ^, which affects the light transmittance and operability of the component, and is long-term at high temperature Under operation, the stability of this indirect layer

569464 V. Description of invention (2) Qualitative is also a problem. Therefore, there is a p-type downward structure that grows a light-emitting diode structure, and the n-type region in the uppermost layer is in contact with I TO to form good ohmic characteristics. However, the p-type region below it is Due to the aforementioned characteristics, the resistance is quite high, which limits the development of this structure. Figure 1 is a schematic diagram of the epitaxial structure of a conventional gallium nitride diode, which includes: a substrate 1 0;-a gallium nitride compound semiconductor low-temperature buffer layer 103;-an undoped gallium nitride compound semiconductor Layer 105;-n-type gallium nitride compound semiconductor layer 107;-gallium nitride compound semiconductor light-emitting active layer 109;-p-type gallium nitride compound semiconductor 1 1 1 Η electrodes 1 1 3 and p-layer transparent electrodes 1 1 5 and ρ electrodes 1 1 7 were fabricated. In the application of the I TO electrode, in order to improve the above problem that the p-type region cannot form a good ohmic contact with the I TO, a P-type downward structure can be used to solve the problem, as shown in FIG. 2. Including: a substrate 201;-gallium nitride compound semiconductor low temperature buffer layer 2 05;-undoped gallium nitride compound semiconductor layer 2 05; a p-type gallium nitride compound semiconductor layer 2 07;-nitride A gallium compound semiconductor light emitting active layer (active 1 ayer) 2 0 9; — n-type gallium nitride compound semiconductor 2 1 1. Through the element process technology, n-type transparent electrodes I TO 2 1 3 and n-layer electrodes 2 1 5 and p-type electrodes 2 1 7 are produced. Under this condition, although the problem of the I TO contact of the n-type gallium nitride compound semiconductor layer 2 1 1 can be solved, the p-type gallium nitride compound semiconductor layer 2 0 7 has a large resistance, thus limiting its use. Although the thickness can be changed to reduce the resistance, the improvement is limited, so how to effectively reduce

The object of the present invention is to propose a structure through which the specific conductivity of the diode element can be increased from ΛΑ through the structure without changing the epitaxial thickness. In the invention, the structure is located in the p layer in the diode epitaxial structure, and the η layer with better conductivity is added, and a tunneling layer is added between the _ n layers 569464 V. Description of the invention (3)

The main problem of the structure of the low-n-type gallium nitride compound semiconductor layer 2 丨 丨 is that the present invention is to propose a p-type downward tunneling effect to solve the problem of high resistance of the diode. [Summary of the Invention] This low-resistance layer is composed of high-concentration P-type and η-type materials, or / and different heterostructures. Under the bias voltage, the current or electron flow passes through the electrode through the low resistance layer through the bias / tunneling effect to reach the 0 layer which is easy to conduct. It moves under the light-emitting layer in the η layer or surface layer, and then passes through the collapse / tunneling effect Into the region of the p layer, and then enter the light-emitting area and combine with electrons to form photons. ^ In order to make the objects and advantages of the present invention more obvious and beneficial, the following will be described by the specific embodiments in the detailed description of the sheep in conjunction with the drawings. [Detailed description of the invention] The present invention will use specific examples and refer to the related drawings to explain the present invention's gallium nitride compound semiconductor system using metal organic chemical vapor phase = product method (MOCVD) or molecular beam epitaxy method (ΜΒΕ) or other epitaxial techniques. The n-type gallium nitride compound semiconductor according to the present invention! The! -Type doped impurity may be: silicon (Si), germanium (Ge), or other elements having the same function: The p-type doped impurity of the p-type gallium nitride compound semiconductor described in the present invention may be

Page 6 569464 V. Description of the invention (4) • Magnesium (Mg), rhenium (Zn), beryllium (Be) or other elements with the same function. A low-resistance layer is a structure that uses a carrier to reduce resistance or operating voltage via, for example, a penetrating effect or a collapse effect, and a substantial structure such as a high concentration (> = 7xl017cm-3) p / n interface, or p + GaN / n + GaN (10 ~ 2 0 0 0 Angstroms); it is a superlattice structure of p / η-type aluminum indium gallium nitride semiconductor layer / p / n-type aluminum indium gallium nitride semiconductor layer (I n xlGa ylA 1 (bxHD N: MgZnS i / I n x2G ay2Al " _x2_y2) N: MgZnSi '(xl'ylS 1, OS x2, y2g 1, OS xl + ylg 1, 0 $ x2 + y2 $ 1), its thickness combination It is 10 to 50 0/1 / 0 to 50 Angstroms (A), the logarithm is between 3 to 100, and the total thickness is about 60 to 1,000 Angstroms (A). (Embodiment 1) FIG. 2 is a schematic diagram illustrating a gallium nitride diode epitaxial structure according to Embodiment 1, including a substrate 3 01, for example, an aluminum oxide (a 丨 203, sapphire), Gallium nitride (GaN), silicon carbide (Sic), gallium arsenide (hAs), silicon (Si), germanium (Ge), silicon germanium (SiGe), etc .; one nitrogen = ί = compound semiconductor buffer layer 3 〇3 Is formed on the surface of the substrate 301 and is crystalline (amorph ous) structure with a thickness of about 50 ~ 500 Angstroms (A); a] doped gallium nitride compound semiconductor layer 305, with a thickness of about 丨 ~ 10 micrometers ^^) an n-type nitrogen The gallium compound semiconductor layer 3 0 7 has a thickness of about 0.1 mm (equivalent m), the aforementioned low-resistance layer 3 9 9 has a structure, composition, and a thick thickness]. A heavily doped P-type gallium nitride compound semiconductor layer 311, 2500 angstroms (A) to 4 micrometers (/ m), a p-type gallium nitride compound half 569464 guards the fish! 1 d, a light-emitting layer 3 1 5, a n-type gallium nitride compound semiconductor layer 317+ ', a heavily doped n-type gallium nitride compound semiconductor layer 319 is formed on the surface of the n-type gallium nitride compound semiconductor layer 317, The thickness is about 500 Angstroms (A) to 2 microns (m) 'to form a good ohmic contact; the contact layer may also be a single layer or multiple low-energy materials such as indium gallium nitride InxGa (1_x) N (〇 < = x < = 1). After the epitaxy is completed, a platform is formed on the P-type gallium nitride compound semiconductor layer 3 1 1 using a coating film, lithography, heat treatment, and coining processes, and a 1τ〇 transparent electrode 321 is produced. A metal contact layer 3 2 3 of 3 21 layers is fabricated on the n-layer semiconductor 31 9, and a p-type contact layer 3 2 5 is fabricated on 3 11 layers. (Embodiment 2) FIG. 4 is a schematic diagram illustrating the gallium nitride diode epitaxial structure of Embodiment 2 including: a substrate 401, the material of which is, for example, alumina (a 1 2 0 3, sapphire), nitrogen Gallium nitride (GaN), silicon carbide (Sic), gallium arsenide (GaAs), silicon (Si), germanium (Ge), silicon germanium (SiGe), etc .; a gallium nitride compound semiconductor buffer layer 403 is formed on the substrate On the surface of 401, it is an amorphous structure with a thickness of about 50 to 50 Angstroms (A); — η or undoped gallium nitride compound semiconductor layer 405, with a thickness of about 1 to 1 0 microns (// m). An n-type gallium nitride compound semiconductor layer 407 has a thickness of about 0.5 to 2 micrometers (// m), and the aforementioned low-resistance layer 409 has the same structure, composition, and thickness as the foregoing. A heavily doped p-type gallium nitride compound semiconductor layer 4 1 1 ′ has a thickness of about 500 angstroms (A) to 4 μm (/ m), a p-type gallium nitride compound semiconductor layer 413, and a light-emitting layer 415. , An n-type gallium nitride compound semiconductor

Page 8 569464 V. Description of the invention (6) Layer 417 'A heavily doped n-type gallium nitride compound semiconductor layer 41-type gallium nitride compound semiconducting semiconductor 4] 7 books; The thickness is about 500 angstroms (A) to 2 microns (// m) to form a good ohmic contact; the contact layer may also be a layer or multiple layers of low energy materials such as indium gallium nitride Ιηχ (^^ Ν (0 < KO). After the epitaxy is completed, a platform is fabricated on the low-resistance layer 409 and used as a transparent ITO electrode layer using coating, lithography, heat treatment, and etching processes. 421 is on _semiconductor 419, and a metal contact layer 423 of m transparent electrode layer 421 is formed on ττο transparent electrode layer 421, and contact layer 4 2 5 is on the low resistance layer. ≪ (Embodiment 3) Figure 5 It is a schematic diagram illustrating the structure of the gallium nitride diode epitaxy of the second embodiment, including: a substrate 501 made of, for example, alumina (A1203, sapphire), gallium nitride (GaN), and silicon carbide (Sic). ), Gallium arsenide (GaAs), silicon (Si), germanium (Ge), silicon germanium (. To), etc .; nitriding, = compound semiconductor buffer layer 503, formed On the surface of the substrate 501, an amorphous structure has a thickness of about 50 to 500 angstroms (A); an n-type or undoped gallium nitride compound semiconductor layer 505 has a thickness of about 50 10 μm (// in). An n-type gallium nitride compound semiconductor layer 507, with a thickness of about 0.5 to 2 micrometers (#m), and the aforementioned low-resistance layer 509, structure and composition. The thickness and thickness are as described above. A heavily doped p-type gallium nitride compound semiconductor layer has a thickness of about 500 angstroms (A) to 4 micrometers (U), and a p-type gallium nitride compound semiconductor layer 5 1 3, A light-emitting layer 5 1 5, an n-type gallium nitride compound semiconductor · layer 5 1 7, a heavily doped n-type gallium nitride compound semiconductor layer 5 丨 9 is formed in type 11

569464 V. Description of the invention " ------ Gasification compound of the tomb (micrometer um)), from the surface of the 517, the thickness is about 500 Angstroms (A) ~ 2 or more to form a good ohmic contact; The contact layer can also be a single layer of yttrium. Materials such as indium gallium nitride 1 nx G a (bu x) N (〇 < = X < = 1), use n film, micro Photolithography process ^ ^ a, the remaining 1 process' nitrided on the n-type gallium nitride compound semiconductor layer 5 0 7 and made 1 τ〇 transparent electrodes 5 2 1 and 5 2 5 are respectively heavily doped η On type 5.0, a semiconductor layer 5 1 9 and an n-type gallium gaseous compound semiconductor layer electrode 521 are coated as a metal contact layer 5 2 3 of a transparent electrode 521 on top of I TO, although it is wonderful. The contact layer 52 7 is on the 5 2 5 layer. Limiting the invention The present invention has been disclosed in the preferred embodiment as above. However, it is not intended to be invented with Fan Yuan. Anyone familiar with this skill can still make changes and decorations without departing from the spirit of the invention. Various changes and those defined in the patent application scope of the present invention.

Page 10 569464 Schematic description [Schematic description] The first diagram is a η-down gallium nitride light-emitting diode structure with a conventional technique. It is not intended. The second figure is a schematic diagram of the structure of a gallium nitride light-emitting diode facing downward. The third figure is a schematic structural diagram illustrating the gallium nitride light emitting diode epitaxial structure of Example 1 of the present invention. The fourth figure is a schematic diagram illustrating the structure of the gallium nitride diode epitaxial structure of the second embodiment. The fifth figure is a schematic diagram illustrating the structure of the gallium nitride diode epitaxial structure of the second embodiment. [Figure No. Description] 101 Substrate 103 GaN compound semiconductor low temperature buffer layer 105 undoped gallium nitride compound semiconductor layer 107 n-type gallium nitride compound semiconductor layer 109 gallium nitride compound semiconductor light emitting active layer 111 p-type gallium nitride compound semiconductor 113 n electrode 115 ρ Layer transparent electrode 1 1 7 ρ electrode 201 substrate 2 0 3 gallium nitride compound semiconductor low temperature buffer layer

569464 Brief description of drawings 2 0 5 undoped gallium nitride compound semiconductor layer 2 0 7 p-type gallium nitride compound semiconductor layer 2 0 9 gallium nitride compound semiconductor light emitting active layer 211 n-type gallium nitride compound semiconductor layer 213 n-type transparent electrode ITO 301 substrate 3 0 3 gallium nitride compound semiconductor buffer layer 3 0 5 n or undoped gallium nitride compound semiconductor layer 3 0 7 n-type gallium nitride compound semiconductor layer 3 0 9 low resistance layer 311 heavily doped p-type gallium nitride compound semiconductor layer 313 p-type gallium nitride compound semiconductor layer 315 light-emitting layer 317 n-type gallium nitride compound semiconductor layer 319 heavily doped n-type gallium nitride compound semiconductor layer 321 I TO transparent Electrode 3 2 3 Metal contact layer 3 2 5 ρ-type contact layer 401 Substrate 40 3 GaN compound semiconductor buffer layer 4 0 5 η or undoped gallium nitride compound semiconductor layer

Page 12 569464 Brief description of the diagram 4 0 7 n-type gallium nitride compound semiconductor layer 4 0 9 Low-resistance layer 411 heavily doped p-type gallium nitride compound semiconductor layer 413 p-type gallium nitride compound semiconductor layer 415 light-emitting layer 417 n-type gallium nitride compound semiconductor layer 419 heavily doped n-type gallium nitride compound semiconductor layer 421 I TO transparent electrode layer 42 3 metal contact layer 42 5 contact layer 501 substrate 5 0 3 gallium nitride compound semiconductor buffer layer 5 0 5 n-type or undoped gallium nitride compound semiconductor layer 5 0 7 n-type gallium nitride compound semiconductor layer 5 0 9 low-resistance layer 511 heavily doped p-type gallium nitride compound semiconductor layer 513 p-type gallium nitride Compound semiconductor layer 515 Light emitting layer 517 n-type gallium nitride compound semiconductor layer 519 heavily doped n-type gallium nitride compound semiconductor layer 521 I TO transparent electrode 5 2 3 metal contact layer

Page 13 569464 Schematic illustration 5 2 5 I TO transparent electrode 5 2 7 Contact layer

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Claims (1)

1 · A low-resistance layer with a low-resistance layer or one of the peak areas · Its structure includes the structure located at p by the tunneling effect, the collapse effect, or OR: the resistive layer is by using carriers Resistance or operating voltage through the crystal structure. Type b effect to reduce the ei 2 · As in the first item of the scope of the patent application, the low-resistance layer is ^ non-degree \ low ^ = light-emitting diode junction 3 · As the second scope of the patent application The structure 'wherein the south concentration of the p / n interface cm (/ cm-3). A light-emitting diode junction with a low-resistance layer has a concentration of at least 7 × 10 17 pieces / cubic patent. The light-emitting diode structure with a low-resistance layer has a thickness of 10 angstroms ( 8) to 2000 Angstroms (A) 5. The light-emitting diode structure having a low-resistance layer according to item 1 of the patent application scope, wherein the low-resistance layer is a ρ / η-type aluminum indium gallium semiconductor layer Superlattice structure (InxlGaylAl (Bu Xbyl) N: MgZnSi / lnx2Gay2Al (Bu x2_y2) N: MgZnSi, (0 $ xl, yl $ 1, x2, y2 $ 1, 0 $ xl + yi $ 1, x2 + y2 $ 1 ), The thickness combination is between 10 and 500 angstroms (A) or between 10 and 500 angstroms (A), the logarithm is between 3 and 100 pairs, and the total thickness is about Between 210 and 100 Angstroms (A). Page 15 569464 _Case No. 91121366_f / 0 β__ VI. Application for patent scope 6. For example, the light-emitting diode structure with a low resistance layer in the scope of patent application No. 1 further includes a lower electrode which is located at P-type aluminum indium gallium nitride semiconductor layer, low-resistance layer structure, or n-type aluminum indium gallium nitride semiconductor layer. Page 16