CN109037371A - (In) the GaN nano-pillar and the preparation method and application thereof being grown on Al substrate - Google Patents

Abstract

The invention discloses an (In)GaN nano column grown on an Al substrate, a preparation method and an application thereof, comprising an AlN buffer layer grown on an Al substrate and an (In)GaN nano column grown on the AlN buffer layer. The Al substrate used wherein has high thermal conductivity and low cost, which is beneficial to solve the problem of heat dissipation of the device and reduce the cost of the device; secondly, the Al substrate used in the present invention has good electrical conductivity and can be directly used as the electrode of the device, which simplifies the construction of the device. Preparation process; the method for preparing (In)GaN nanocolumns grown on an Al substrate in the present invention has the advantages of simple growth process and low preparation cost, and the (In)GaN nanocolumns prepared by the present invention have good crystal quality and low defect It has the characteristics of low density and stress relaxation, and can be used to prepare light-emitting diodes, photodetectors and solar cells.

Description

(In)GaN Nanocolumns Grown on Al Substrate and Its Preparation Method and Application

technical field

The invention relates to (In)GaN nanocolumns, in particular to (In)GaN nanocolumns grown on an Al substrate, a preparation method and application thereof.

Background technique

Group III nitride (In)GaN has extremely excellent properties in electricity, optics and acoustics, and has attracted extensive attention in recent years. (In)GaN is a direct bandgap material with good chemical and thermal stability, high thermal conductivity, high electron mobility, and high breakdown dielectric strength. It is widely used in light-emitting diodes (LEDs), lasers (LDs), high Electron mobility transistor (HEMT), etc.

Compared with thin-film materials, (In)GaN nanopillars have a high specific surface area, and its high specific surface area allows the lattice strain due to the lattice mismatch between the nanopillars and the substrate to be effectively relaxed at the sidewalls of the nanopillars. , can significantly reduce the threading dislocation density, obtain nano-column materials with high crystal quality, effectively suppress the piezoelectric polarization effect of the device and improve the device performance. Due to the significant size reduction, (In)GaN nanopillars provide a new avenue for future downsizing of devices and systems. In addition, (In)GaN nanopillars also exhibit more novel properties in terms of quantum effects, interface effects, volume effects, and size effects, which make them have great prospects in basic physical science and new technology applications.

At present, thin-film and nanopillar GaN-based devices are mainly grown on sapphire and single-crystal Si substrates. And they often have low thermal conductivity (sapphire 25W/m K, Si single crystal 156W/m K), high resistivity (sapphire 1014Ω cm, doped Si ~ 10Ω cm), sapphire substrate high cost issues. When the thermal conductivity of the substrate is low, it is difficult to discharge the heat generated by the GaN-based device in time, resulting in heat accumulation and ultimately affecting the performance of the device. When sapphire and single crystal Si with high resistivity are used as the substrate material of (In)GaN nanopillar-based devices, when preparing electrodes, it is necessary to evaporate multiple metal layers to form ohmic contacts, which increases the complexity of the device process. Therefore, it is of great significance to find a substrate material with low price, high thermal conductivity and good electrical conductivity for growing (In)GaN nanopillars for the application of (In)GaN nanopillar-based devices.

Contents of the invention

In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the object of the present invention is to provide a kind of (In)GaN nanocolumn grown on the Al substrate, the substrate cost of this nanocolumn is low, thermal conductivity is high, electrical conductivity is good . The metal Al substrate has a high thermal conductivity, which can conduct the heat generated when the (In)GaN nanopillar-based device works in a timely manner, which helps to solve the heat dissipation problem of the device. Secondly, the metal Al substrate can be directly used as the electrode of the device without preparing an ohmic contact electrode, which simplifies the device process. Again, the price of the metal Al substrate is relatively low, which is conducive to reducing the cost of the device.

Another object of the present invention is to provide a preparation method and application of (In)GaN nanocolumns grown on an Al substrate. The study found that the nanocolumn structure formed by reducing the size of the (In)GaN epitaxial layer to the nanometer range is strain-relaxed, has almost no defects, and has high crystal quality.

The purpose of the present invention is achieved through the following technical solutions.

The (In)GaN nanocolumn grown on the Al substrate comprises an Al substrate 1, an AlN buffer layer 2 grown on the Al substrate 1, and an (In)GaN nanocolumn 3 grown on the AlN buffer layer.

Preferably, the Al substrate is common Al metal.

Preferably, the thickness of the AlN buffer layer is 5-50 nm, and when the thickness of the AlN buffer layer reaches 5-50 nm, the stress of the grown (In)GaN nanocolumns is released. In addition, due to the large specific surface area of (In)GaN nanopillars, the strain is effectively relaxed on the sidewalls of the nanopillars, which is beneficial to the growth of high-quality (In)GaN nanopillars on Al substrates.

Preferably, the (In)GaN nanocolumns include GaN, InGaN, InN nanocolumns.

Preferably, the (In)GaN nanocolumns have a height of 60-2000 nm and a diameter of 15-500 nm.

The method for preparing the above-mentioned (In)GaN nanocolumn grown on an Al substrate comprises the following steps:

(1) Selection of substrate: Al substrate is used;

(2) Surface polishing of the substrate: polishing the surface of the Al substrate with diamond slurry, observing the surface of the substrate with an optical microscope until there are no scratches, and then polishing by chemical mechanical polishing;

(3) Substrate cleaning: ultrasonically clean the Al substrate after step (2) polishing to remove residual organic matter on the surface, and finally dry it with high-purity dry nitrogen;

(4) Substrate annealing treatment: put the Al substrate obtained in step (3) into the reaction chamber, and perform annealing treatment on the Al substrate at 500-650° C. to obtain a smooth surface;

(5) Preparation of AlN buffer layer: control the temperature of the Al substrate obtained in step (4) to be 450-650° C., and the rotating speed is 5-10 r/min, and then use a nitrogen plasma source to nitride the surface of the Al substrate. The power of the source is 200-450W, the flow rate of nitrogen gas is 1-5sccm, and an AlN buffer layer is obtained on the Al substrate, which is conducive to the growth of subsequent (In)GaN nanocolumns;

(6) Preparation of (In)GaN nanocolumns: using molecular beam epitaxy growth process, controlling the substrate temperature at 450-650°C, the rotation speed at 5-10r/min, and the Ga beam flow rate at 1.0×10 ^-8 to 1.5× 10 ^-7 Torr, In beam flow of 1.0×10 ^-8 to 5×10 ^-7 Torr, nitrogen flow of 1 to 5 sccm, plasma source power of 200 to 450 W, on the AlN buffer layer obtained in step (5) Growth of (In)GaN nanopillars.

Preferably, the ultrasonic cleaning in step (3) is to ultrasonically clean the Al substrate with acetone, ethanol and water for 2-5 minutes respectively.

Preferably, the annealing treatment time in step (4) is 0.5-1 hour.

Preferably, the nitriding time in step (5) is 10-50 minutes.

The (In)GaN nanocolumns grown on the Al substrate described above are applied to the preparation of light-emitting diodes, photodetectors and solar cells.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) The present invention uses ordinary Al metal as the substrate, which is cheaper than other substrate materials, such as sapphire and single crystal Si substrate, which is conducive to reducing device manufacturing costs.

(2) Al metal substrate has very high thermal conductivity, which is 217.7W/m·K. Using Al metal as the substrate material of (In)GaN nanopillars can quickly conduct the heat generated by (In)GaN nanopillar-based devices during operation, which helps to solve the heat dissipation problem of the device and increase the service life of the device.

(3) As the substrate material for growing (In)GaN nanocolumns, Al metal can be directly used as the electrode of the device. In this way, there is no need to vapor-deposit multi-layer metals to prepare ohmic contact electrodes, which simplifies the device preparation process.

(4) The present invention uses Al metal as a substrate, and directly nitridizes the surface of the substrate to form an AlN buffer layer, without pre-depositing a layer of metal Al film, and the process is simple and easy. The formation of the AlN buffer layer is beneficial to the nucleation and growth of the subsequent (In)GaN nanocolumns, and when the thickness of the AlN buffer layer reaches 5-50nm, the (In)GaN nanocolumns are in a relaxed state; in addition, (In)GaN nanocolumns are in a relaxed state; Due to the large specific surface area of the nanocolumns, the strain is effectively relaxed on the sidewalls of the nanocolumns, which is beneficial to the growth of high-quality (In)GaN nanocolumns on the Al metal substrate.

(5) The (In)GaN nanocolumn prepared by the present invention has high crystal quality and low dislocation density. On the one hand, the use of the AlN buffer layer reduces the lattice mismatch between the Al substrate and (In)GaN, can effectively reduce the formation of dislocations, and is conducive to the growth of high-quality (In)GaN nanocolumns; On the one hand, the (In)GaN nanopillar structure is strain-relaxed, almost defect-free, and of high crystal quality. The finally prepared (In)GaN nanocolumns with high crystal quality can greatly reduce the probability of non-radiative recombination of carriers, and can greatly improve the device efficiency of nitride devices such as lasers, light-emitting diodes and solar cells.

Description of drawings

1 is a schematic cross-sectional view of InGaN nanocolumns grown on an Al substrate in Example 1.

FIG. 2 is an SEM top view of InGaN nanocolumns grown on Al substrates in Example 1. FIG.

Detailed ways

The present invention will be described in further detail below in conjunction with the examples, but the embodiments of the present invention are not limited thereto.

Example 1

The preparation method of the InGaN nano column grown on the Al substrate comprises the following steps:

(1) Selection of the substrate: ordinary Al metal is used as the substrate.

(2) Surface polishing of the substrate: Polish the surface of the Al substrate with diamond slurry, observe the surface of the substrate with an optical microscope until there are no scratches, and then perform polishing treatment by chemical mechanical polishing.

(3) Substrate cleaning: the Al substrate was ultrasonically cleaned with acetone, ethanol, and deionized water for 3 minutes each, and finally dried with high-purity dry nitrogen.

(4) Substrate annealing treatment: put the substrate into the reaction chamber, and perform annealing treatment on the Al substrate at 550° C. for 1 hour.

(5) Formation of the AlN buffer layer: the substrate temperature is controlled at 500°C, the substrate speed is 10r/min, and then the surface of the Al substrate is nitrided using a nitrogen plasma source, the power of the plasma source is 300W, and the nitrogen flow rate is 2 sccm, after 10 minutes of nitriding, an AlN buffer layer was obtained.

(6) Preparation of high-quality InGaN nanocolumns: the molecular beam epitaxy growth process is adopted, the substrate temperature is 500°C, the substrate speed is 10r/min, the Ga beam flow rate is 8×10 ^-8 Torr, and the In beam flow rate is 3×10 ^-7 Torr, nitrogen gas flow rate of 2 sccm, plasma source power of 250 W, and grow InN nanocolumns on the AlN buffer layer obtained in step (5).

As shown in Figure 1, the cross-sectional schematic view of the InGaN nanocolumn grown on the Al substrate in this embodiment includes the Al substrate 1, the AlN buffer layer 2 grown on the Al substrate 1, the AlN buffer layer 2 grown on the Al substrate InGaN nanopillar3.

As shown in FIG. 2 , the scanning electron microscope top view of the InGaN nanocolumns grown on the Al substrate in this embodiment.

Example 2

The preparation method of the InN nano column grown on the Al substrate comprises the following steps:

(1) Selection of the substrate: ordinary Al metal is used as the substrate.

(2) Surface polishing of the substrate: Polish the surface of the Al substrate with diamond slurry, observe the surface of the substrate with an optical microscope until there are no scratches, and then perform polishing treatment by chemical mechanical polishing.

(3) Substrate cleaning: the Al substrate was ultrasonically cleaned with acetone, ethanol, and deionized water for 2 minutes each, and finally dried with high-purity dry nitrogen.

(4) Substrate annealing treatment: put the substrate into the reaction chamber, and perform annealing treatment on the Al substrate at 500° C. for 1 hour.

(5) Formation of the AlN buffer layer: the substrate temperature is controlled at 450°C, the substrate speed is 5r/min, and then the surface of the Al substrate is nitrided by a nitrogen plasma source, the power of the plasma source is 200W, and the nitrogen flow rate is 1 sccm, after 50 minutes of nitriding, an AlN buffer layer was obtained.

(6) Preparation of high-quality InGaN nanocolumns: the molecular beam epitaxy growth process is adopted, the substrate temperature is 450°C, the substrate speed is 10r/min, the Ga beam flow rate is 1.0×10 ^-8 Torr, and the In beam flow rate is 5×10 ^-7 Torr, the nitrogen gas flow rate is 5 sccm, the plasma source power is 450 W, and the InN nanocolumns are grown on the AlN buffer layer obtained in step (5).

Example 3

The preparation method of the GaN nano column grown on the Al substrate comprises the following steps:

(1) Selection of the substrate: ordinary Al metal is used as the substrate.

(2) Surface polishing of the substrate: Polish the surface of the Al substrate with diamond slurry, observe the surface of the substrate with an optical microscope until there are no scratches, and then perform polishing treatment by chemical mechanical polishing.

(3) Substrate cleaning: The substrate was ultrasonically cleaned with acetone, ethanol, and deionized water for 5 minutes each, and finally dried with high-purity dry nitrogen.

(4) Substrate annealing treatment: put the substrate into the reaction chamber, and perform annealing treatment on the Al substrate at 650° C. for 0.5 hour.

(5) Formation of the AlN buffer layer: the substrate temperature is controlled at 650°C, the substrate speed is 10r/min, and then the surface of the Al substrate is nitrided with a nitrogen plasma source, the power of the plasma source is 450W, and the nitrogen flow rate is 5 sccm, after 10 minutes of nitriding, an AlN buffer layer was obtained.

(6) Preparation of high-quality GaN nanocolumns: the molecular beam epitaxy growth process was adopted, the substrate temperature was 650°C, the substrate speed was 5r/min, the In beam flow rate was 1.0×10 ^-8 Torr, and the Ga beam flow rate was 1.5×10 ^-7 Torr, nitrogen gas flow rate of 1.0 sccm, and plasma source power of 200 W, GaN nanocolumns were grown on the AlN buffer layer obtained in step (5).

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the embodiment, and any other changes, modifications, substitutions and combinations made without departing from the spirit and principle of the present invention , simplification, all should be equivalent replacement methods, and are all included in the protection scope of the present invention.

Claims (10)

1. The (In)GaN nanocolumn grown on the Al substrate is characterized in that, comprises the Al substrate (1), the AlN buffer layer (2) grown on the Al substrate (1), the AlN buffer layer grown on the AlN buffer layer (In)GaN nanopillars (3) on (2). 2. The (In)GaN nanocolumn grown on an Al substrate according to claim 1, wherein the Al substrate is ordinary Al metal. 3. the (In)GaN nanocolumn growing on the Al substrate according to claim 1, is characterized in that, the thickness of described AlN buffer layer is 5～50 nm. 4. the (In)GaN nanocolumn growing on the Al substrate according to claim 1, is characterized in that, described (In)GaN nanocolumn comprises GaN, InGaN, InN nanocolumn. 5. The (In)GaN nanocolumn grown on an Al substrate according to claim 4, wherein the (In)GaN nanocolumn has a height of 60-2000 nm and a diameter of 15-500 nm. 6. the method for preparing the (In)GaN nanocolumn growing on the Al substrate described in any one of claim 1-5, is characterized in that, comprises the following steps: (1) Selection of substrate: Al substrate is used; (2) Surface polishing of the substrate: Polish the surface of the Al substrate with diamond slurry, and observe the surface of the substrate with an optical microscope until there are no scratches, and then polish it by chemical mechanical polishing; (3) Substrate cleaning: ultrasonically clean the polished Al substrate in step (2) to remove residual organic matter on the surface, and finally dry it with high-purity dry nitrogen; (4) Substrate annealing treatment: put the Al substrate obtained in step (3) into the reaction chamber, and anneal the Al substrate at 500-650 ºC to obtain a smooth surface; (5) Preparation of AlN buffer layer: control the temperature of the Al substrate obtained in step (4) at 450-650 ºC, and the rotation speed at 5-10 r/min, and then use a nitrogen plasma source to nitride the surface of the Al substrate. The power of the bulk source is 200~450 W, the nitrogen flow rate is 1~5 sccm, and the AlN buffer layer is obtained on the Al substrate; (6) Preparation of (In)GaN nanocolumns: using the molecular beam epitaxy growth process, controlling the substrate temperature at 450~650 ºC, the rotation speed at 5~10 r/min, and the Ga beam flow at 1.0×10 ^-8 ~1.5 ×10 ^-7 Torr, the In beam flow rate is 1.0×10 ^-8 ~5×10 ^-7 Torr, the nitrogen flow rate is 1~5 sccm, the plasma source power is 200~450 W, the AlN obtained in step (5) (In)GaN nanopillars are grown on the buffer layer. 7. The preparation method according to claim 6, wherein the ultrasonic cleaning in step (3) is to ultrasonically clean the Al substrate with acetone, ethanol, and water for 2-5 min respectively. 8 . The preparation method according to claim 6 , wherein the annealing treatment in step (4) takes 0.5 to 1 hour. 9. The preparation method according to claim 6, characterized in that the nitriding time in step (5) is 10-50 minutes. 10. The (In)GaN nanocolumn grown on the Al substrate according to any one of claims 1-5 is applied to the preparation of light-emitting diodes, photodetectors and solar cells.