阅读说明：本技术 改善p型氮化镓欧姆的方法 (Method for improving p-type gallium nitride ohm ) 是由 梁锋 赵德刚 刘宗顺 朱建军 陈平 杨静 于 2020-04-03 设计创作，主要内容包括：本公开提供了一种改善p型氮化镓欧姆的方法,包括：步骤1：在衬底上生长低温氮化镓缓冲层；步骤2：在低温氮化镓缓冲层上生长高温非故意掺杂氮化镓层；步骤3：在高温非故意掺杂氮化镓层上生长中度掺镁p型氮化镓；步骤4：在中度掺镁p型氮化镓上生长重掺镁p型氮化镓。本公开通过调整重掺镁p型氮化镓的外延生长条件,控制该层中碳杂质浓度,可有效降低比接触电阻率,改善p型氮化镓的欧姆接触。(The present disclosure provides a method of improving p-type gallium nitride ohms, comprising: step 1: growing a low-temperature gallium nitride buffer layer on a substrate; step 2: growing a high-temperature unintended doped gallium nitride layer on the low-temperature gallium nitride buffer layer; and step 3: growing medium magnesium-doped p-type gallium nitride on the high-temperature unintentionally doped gallium nitride layer; and 4, step 4: heavily Mg-doped p-type gallium nitride is grown on the moderately Mg-doped p-type gallium nitride. The method can effectively reduce specific contact resistivity and improve ohmic contact of p-type gallium nitride by adjusting epitaxial growth conditions of heavily magnesium-doped p-type gallium nitride and controlling the concentration of carbon impurities in the layer.)

1. A method of improving p-type gallium nitride ohms, comprising:

step 1: growing a low-temperature gallium nitride buffer layer on a substrate;

step 2: growing a high-temperature unintended doped gallium nitride layer on the low-temperature gallium nitride buffer layer;

and step 3: growing medium magnesium-doped p-type gallium nitride on the high-temperature unintentionally doped gallium nitride layer;

and 4, step 4: heavily Mg-doped p-type gallium nitride is grown on the moderately Mg-doped p-type gallium nitride.

2. The method for improving p-type GaN ohmic of claim 1, wherein in the step 4, the heavily Mg-doped p-type GaN layer is grown at 800-1000 deg.C, under 10-500 Torr, with a thickness of 10-100 nm and a Mg impurity concentration of 1 × 10¹⁹cm^-3～1×10²¹cm^-3。

3. The method for improving p-type GaN ohmic contact of claim 1, wherein in step 3, the growth temperature of the moderately Mg-doped p-type GaN layer is 800-1500 ℃, the pressure is 10Torr-500Torr, the thickness is 10 nm-1000 nm, and the Mg impurity concentration is 1 × 10¹⁸cm^-3～5×10¹⁹cm^-3。

4. The method for improving p-type GaN ohm according to claim 1, wherein in the step 2, the growth temperature of the high-temperature unintentionally doped GaN layer is 800-1500 ℃ and the thickness is 10-4000 nm.

5. The method for improving p-type GaN ohm as claimed in claim 1, wherein in step 1, the growth temperature of the low-temperature GaN buffer layer is 400-700 ℃ and the thickness is 10-50 nm.

6. The method for improving p-type GaN ohmic according to any of claims 1 to 5, further comprising:

and 5: growing a metal layer on the heavily magnesium-doped p-type gallium nitride; the metal layer is made of nickel-gold alloy, wherein the thickness of nickel is 10nm-50nm, and the thickness of gold is 10-50 nm.

7. The method for improving p-type GaN ohmic of claim 6, wherein in step 5, the metal layer is prepared by electron beam evaporation or magnetron sputtering.

8. The method for improving p-type GaN ohmic according to any of claims 1 to 5, wherein the growth method in steps 1 to 4 is a vapor deposition method.

9. The method for improving p-type GaN ohmic according to any of claims 1 to 5, wherein the material of the substrate is one or more of silicon, sapphire, silicon carbide and gallium nitride.

Technical Field

The disclosure relates to the field of semiconductor material growth and device preparation, and in particular relates to a method for improving p-type gallium nitride ohm.

Background

Gallium nitride material systems are excellent in the fields of photoelectronic and microelectronic devices such as solid-state light-emitting diodes, blue/green lasers, high electron mobility transistors and solar cells. The gallium nitride-based laser has the advantages of adjustable wavelength, high efficiency, small volume, controllable time and space and the like, and has important application value in the fields of submarine communication, laser mine exploration, laser display, laser micro projection, laser illumination and the like.

How to obtain good p-type gallium nitride ohmic contact is an important basis for wide application of gallium nitride-based devices, for example, the working voltage of a gallium nitride-based laser is directly related to the p-type ohmic contact. However, since the ionization energy of the magnesium acceptor impurity in p-type gallium nitride is as high as 200meV, and the magnesium acceptor is compensated by impurities or defects in the gallium nitride, the hole concentration is low, and furthermore, a metal having a higher work function than p-type gallium nitride is absent, so that it is difficult to realize a high-quality p-type gallium nitride ohmic contact. Therefore, improving p-type gallium nitride ohmic contact is the key to improving gallium nitride-based devices.

Disclosure of Invention

Technical problem to be solved

The present disclosure provides a method for improving p-type gan ohmic contact by reducing specific ohmic contact resistivity to at least partially solve the above-identified problems.

(II) technical scheme

According to an aspect of the present disclosure, there is also provided a method of improving p-type gallium nitride ohm, including:

step 1: growing a low-temperature gallium nitride buffer layer on a substrate;

step 2: growing a high-temperature unintended doped gallium nitride layer on the low-temperature gallium nitride buffer layer;

and step 3: growing medium magnesium-doped p-type gallium nitride on the high-temperature unintentionally doped gallium nitride layer;

and 4, step 4: heavily Mg-doped p-type gallium nitride is grown on the moderately Mg-doped p-type gallium nitride.

In some embodiments of the present disclosure, in the step 4, the growth temperature of the heavily magnesium-doped p-type gallium nitride layer is 800 ℃ to 1000 ℃, the pressure is 10Torr to 500Torr, the thickness is 10nm to 100nm, and the concentration of the magnesium impurity is 1 × 10¹⁹cm^-3～1×10²¹cm^-3。

In some embodiments of the present disclosure, in the step 3, the growth temperature of the moderately magnesium-doped p-type gallium nitride layer is 800 ℃ to 1500 ℃, the pressure is 10Torr to 500Torr, the thickness is 10nm to 1000nm, and the concentration of the magnesium impurity is 1 × 10¹⁸cm^-3～5×10¹⁹cm^-3。

In some embodiments of the present disclosure, in the step 2, the growth temperature of the high-temperature unintentionally doped gallium nitride layer is 800 ℃ to 1500 ℃ and the thickness is 10nm to 4000 nm.

In some embodiments of the present disclosure, in step 1, the growth temperature of the low-temperature gallium nitride buffer layer is 400-700 ℃ and the thickness is 10-50 nm.

In some embodiments of the present disclosure, further comprising:

and 5: growing a metal layer on the heavily magnesium-doped p-type gallium nitride; the metal layer is made of nickel-gold alloy, wherein the thickness of nickel is 10nm-50nm, and the thickness of gold is 10-50 nm.

In some embodiments of the present disclosure, in the step 5, the metal layer is prepared by electron beam evaporation or magnetron sputtering.

In some embodiments of the present disclosure, the growth method in the step 1 to the step 4 is a vapor deposition method.

In some embodiments of the present disclosure, the material of the substrate is one or more of silicon, sapphire, silicon carbide, and gallium nitride.

(III) advantageous effects

From the technical scheme, the method for improving p-type gallium nitride ohm has at least one or part of the following beneficial effects:

(1) the specific contact resistivity can be effectively reduced by regulating and controlling the concentration of carbon impurities in the heavily doped p-type gallium nitride.

(2) The method directly utilizes the growth conditions to control the concentration of carbon impurities in the heavily doped p-type gallium nitride, and the growth regulation process is simple.

(3) The method directly utilizes carbon in the metal organic compound as a carbon source, does not need to additionally introduce a new doping material, improves the utilization efficiency and simplifies the process.

(4) The ohmic contact with low specific contact resistivity is realized by selecting a proper metal system, particularly a nickel-gold double-layer metal film.

Drawings

Fig. 1 is a block flow diagram of a method for improving p-type gan ohmic contact according to an embodiment of the present disclosure.

Fig. 2 is a schematic cross-sectional structure diagram corresponding to step 5 of the method for improving p-type gallium nitride ohm according to the embodiment of the disclosure.

Fig. 3 is a schematic top view structure diagram corresponding to step 5 of the method for improving p-type gan ohmic contact according to the embodiment of the disclosure.

Fig. 4 is a schematic diagram illustrating a dependence of specific contact resistivity on a carbon impurity concentration in the p-type heavily magnesium-doped gallium nitride layer in the embodiment of the present disclosure.

[ description of main reference numerals in the drawings ] of the embodiments of the present disclosure

1-a substrate;

2-a low temperature gallium nitride buffer layer;

3-high temperature unintentional doping of gallium nitride layer;

4-moderate magnesium-doped p-type gallium nitride layer;

5-heavily doped magnesium p-type gallium nitride layer;

6-metal layer.

Detailed Description

The present disclosure provides a method of improving p-type gallium nitride ohms, comprising: step 1: growing a low-temperature gallium nitride buffer layer on a substrate; step 2: growing a high-temperature unintended doped gallium nitride layer on the low-temperature gallium nitride buffer layer; and step 3: growing medium magnesium-doped p-type gallium nitride on the high-temperature unintentionally doped gallium nitride layer; and 4, step 4: heavily Mg-doped p-type gallium nitride is grown on the moderately Mg-doped p-type gallium nitride. The method can effectively reduce specific contact resistivity and improve ohmic contact of p-type gallium nitride by adjusting epitaxial growth conditions of heavily magnesium-doped p-type gallium nitride and controlling the concentration of carbon impurities in the layer.

For the purpose of promoting a better understanding of the objects, aspects and advantages of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.

Certain embodiments of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the disclosure are shown. Indeed, various embodiments of the disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements.

In one exemplary embodiment of the present disclosure, a method of improving p-type gallium nitride ohms is provided. Fig. 1 is a block flow diagram of a method for improving p-type gan ohmic contact according to an embodiment of the present disclosure. As shown in fig. 1, the method for improving p-type gallium nitride ohm comprises the following steps:

step 1: growing a low-temperature gallium nitride buffer layer on the substrate. Specifically, the growth temperature of the low-temperature gallium nitride buffer layer is 400-700 ℃, and the thickness is 10-50 nm.

Step 2: and growing a high-temperature unintentional doped gallium nitride layer on the low-temperature gallium nitride buffer layer. Specifically, the growth temperature of the high-temperature unintentional doped gallium nitride layer is 800-1500 ℃, and the thickness is 10-4000 nm.

Step 3, growing moderate magnesium-doped p-type gallium nitride on the high-temperature unintentionally doped gallium nitride layer, wherein the growth temperature of the moderate magnesium-doped p-type gallium nitride layer is 800-1500 ℃, the pressure is 10Torr-500Torr, the thickness is 10 nm-1000 nm, the concentration of magnesium impurities is 1 × 10¹⁸cm^-3～5×10¹⁹cm^-3。

Step 4, growing heavily-doped Mg-p-type gallium nitride on the moderately-doped Mg-p-type gallium nitride, specifically, the growing temperature of the heavily-doped Mg-p-type gallium nitride layer is 800-1000 ℃, the pressure is 10Torr-500Torr, the thickness is 10 nm-100 nm, the concentration of Mg impurities is 1 × 10¹⁹cm^-3～1×10²¹cm^-3。

And 5: and growing a metal layer on the heavily magnesium-doped p-type gallium nitride. Specifically, the metal layer is made of nickel-gold alloy, wherein the thickness of nickel is 10nm-50nm, and the thickness of gold is 10-50 nm. As shown in fig. 2 and 3.