METAL-DOPED GALLIUM OXIDE TRANSPARENT CONDUCTIVE THIN FILM FOR ULTRAVIOLET WAVEBAND AND PREPARATION METHOD THEREFOR

Abstract

A preparation method for a metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband includes: growing a contact layer thin film (2) on a substrate (1) first, and annealing the grown contact layer thin film (2) in a nitrogen-oxygen atmosphere at 400° C. to 600° C. through a rapid thermal annealing furnace; growing a first Ga.sub.2O.sub.3 thin film (31) by sputtering through magnetron sputtering under argon conditions; growing a doped thin film (4) by sputtering through magnetron sputtering under argon conditions; growing a second Ga.sub.2O.sub.3 thin film (32) by sputtering through magnetron sputtering under argon conditions; and annealing the grown thin films in a nitrogen-oxygen atmosphere at 500° C. to 600° C. through a rapid thermal annealing furnace, so that permeation, diffusion and fusion occur between thin film materials to form a metal-doped Ga.sub.2O.sub.3 thin film (5). A metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband is provided.

Claims

1. A preparation method for a metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband, wherein the preparation method comprises the following steps: 1) growing a contact layer thin film on a substrate using an electron beam conventionally, and annealing the grown contact layer thin film in a nitrogen-oxygen atmosphere at 400° C. to 600° C. through a rapid thermal annealing furnace; 2) growing a first Ga.sub.2O.sub.3 thin film by sputtering through magnetron sputtering under argon conditions, and controlling a thickness of the first Ga.sub.2O.sub.3 thin film to be 10 nm to 20 nm; 3) growing a doped thin film by sputtering through magnetron sputtering under argon conditions, the doped thin film being an Ag, Al or Ti thin film, and controlling a thickness of the doped thin film to be 3 nm to 7 nm; 4) growing a second Ga.sub.2O.sub.3 thin film by sputtering through magnetron sputtering under argon conditions, and controlling a thickness of the second Ga.sub.2O.sub.3 thin film to be 10 nm to 20 nm; and 5) annealing the grown thin films integrally in a nitrogen-oxygen atmosphere at 500° C. to 600° C. through the rapid thermal annealing furnace, so that permeation, diffusion and fusion occur between thin film materials to form a metal-doped Ga.sub.2O.sub.3 thin film.

2. The preparation method for the metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband according to claim 1, wherein the substrate in the step 1) is obtained by washing respectively with sulfuric acid, hydrogen peroxide, and ammonia water in a water bath at 60° C.

3. The preparation method for the metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband according to claim 1, wherein the substrate in the step 1) is circular, with a thickness of 1 mm to 2 mm; and the substrate is a GaN-based LED epitaxy.

4. The preparation method for the metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband according to claim 1, wherein the contact layer thin film in the step 1) is made of ITO or Ni, and if the contact layer thin film is made of the ITO, the ITO has a growth thickness of 10 nm to 20 nm; and if the contact layer thin film is made of the Ni, the Ni has a growth thickness of 1 nm to 4 nm.

5. The preparation method for the metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband according to claim 1, wherein the magnetron sputtering in the step 2) has a power of 120 W to 140 W, a substrate rotation speed of 20 rmp, and a pressure of 5 mtorr; and the sputtering lasts for 5 minutes to 10 minutes.

6. The preparation method for the metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband according to claim 1, wherein the magnetron sputtering in the step 3) has a power of 100 W to 120 W, a substrate rotation speed of 20 rmp, and a pressure of 5 mtorr.

7. The preparation method for the metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband according to claim 1, wherein the magnetron sputtering in the step 4) has a power of 120 W to 140 Wa substrate rotation speed of 20 rmp, and a pressure of 5 mtorr; and the sputtering lasts for 5 minutes to 10 minutes.

8. The preparation method for the metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband according to claim 1, wherein the metal-doped Ga.sub.2O.sub.3 thin film in the step 5) is formed by fusing the contact layer thin film, the first Ga.sub.2O.sub.3 thin film, the doped thin film[[ 4]], and the second Ga.sub.2O.sub.3 thin film; and the metal-doped Ga.sub.2O.sub.3 thin film has a thickness of 24 nm to 67 nm.

9. The preparation method for the metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband according to claim 1, wherein the annealing in both the step 1) and the step 5) lasts for 1 minute to 5 minutes.

10. A metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband, wherein the ultraviolet waveband metal-doped gallium oxide transparent conductive thin film is prepared by the preparation method according to claim 1; and the metal-doped gallium oxide transparent conductive thin film has a square resistance lower than 20 Ω/sq, and a transmittance higher than 90% in an ultraviolet waveband above 330 nm.

11. A metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband, wherein the ultraviolet waveband metal-doped gallium oxide transparent conductive thin film is prepared by the preparation method according to claim 2; and the metal-doped gallium oxide transparent conductive thin film has a square resistance lower than 20 Ω/sq, and a transmittance higher than 90% in an ultraviolet waveband above 330 nm.

12. A metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband, wherein the ultraviolet waveband metal-doped gallium oxide transparent conductive thin film is prepared by the preparation method according to claim 3; and the metal-doped gallium oxide transparent conductive thin film has a square resistance lower than 20 Ω/sq, and a transmittance higher than 90% in an ultraviolet waveband above 330 nm.

13. A metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband, wherein the ultraviolet waveband metal-doped gallium oxide transparent conductive thin film is prepared by the preparation method according to claim 4; and the metal-doped gallium oxide transparent conductive thin film has a square resistance lower than 20 Ω/sq, and a transmittance higher than 90% in an ultraviolet waveband above 330 nm.

14. A metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband, wherein the ultraviolet waveband metal-doped gallium oxide transparent conductive thin film is prepared by the preparation method according to claim 5; and the metal-doped gallium oxide transparent conductive thin film has a square resistance lower than 20 Ω/sq, and a transmittance higher than 90% in an ultraviolet waveband above 330 nm.

15. A metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband, wherein the ultraviolet waveband metal-doped gallium oxide transparent conductive thin film is prepared by the preparation method according to claim 6; and the metal-doped gallium oxide transparent conductive thin film has a square resistance lower than 20 Ω/sq, and a transmittance higher than 90% in an ultraviolet waveband above 330 nm.

16. A metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband, wherein the ultraviolet waveband metal-doped gallium oxide transparent conductive thin film is prepared by the preparation method according to claim 7; and the metal-doped gallium oxide transparent conductive thin film has a square resistance lower than 20 Ω/sq, and a transmittance higher than 90% in an ultraviolet waveband above 330 nm.

17. A metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband, wherein the ultraviolet waveband metal-doped gallium oxide transparent conductive thin film is prepared by the preparation method according to claim 8; and the metal-doped gallium oxide transparent conductive thin film has a square resistance lower than 20 Ω/sq, and a transmittance higher than 90% in an ultraviolet waveband above 330 nm.

18. A metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband, wherein the ultraviolet waveband metal-doped gallium oxide transparent conductive thin film is prepared by the preparation method according to claim 9; and the metal-doped gallium oxide transparent conductive thin film has a square resistance lower than 20 Ω/sq, and a transmittance higher than 90% in an ultraviolet waveband above 330 nm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Description of the Drawings

[0031] FIG. 1 is a schematic cross-sectional view of a transparent conductive thin film before annealing in Embodiment 1.

[0032] FIG. 2 is a schematic cross-sectional view of a Ga.sub.2O.sub.3 transparent conductive thin film for ultraviolet waveband after annealing in Embodiment 1.

[0033] FIG. 3 is a curve graph of transmittances of the Ga.sub.2O.sub.3 transparent conductive thin film for ultraviolet waveband in Embodiment 1 and an ordinary 90 nm ITO thin film.

[0034] In the drawings, 1 refers to substrate, 2 refers to contact layer thin film, 31 refers to first Ga.sub.2O.sub.3 thin film, 4 refers to doped thin film, 32 refers to second Ga.sub.2O.sub.3 thin film, and 5 refers to metal-doped Ga.sub.2O.sub.3 thin film.

DESCRIPTION OF THE EMBODIMENTS

Implementations of the Present Invention

[0035] In order to better understand the present invention, the present invention is further described hereinafter with reference to the accompanying drawings and the embodiments, but the implementations of the present invention are not limited hereto.

Embodiment 1

[0036] FIG. 1 is a schematic cross-sectional view of a novel metal-doped Ga.sub.2O.sub.3 thin film before high-temperature annealing in a specific embodiment.

[0037] As shown in FIG. 1, a preparation method for a metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband included the following steps:

[0038] 1) a contact layer thin film 2 was conventionally grown on a substrate 1 respectively washed with sulfuric acid, hydrogen peroxide, and ammonia water in a water bath at 60° C. using an electron beam evaporation first, the contact layer thin film 2 was ITO, with a thickness of 10 nm, and was annealed in a nitrogen-oxygen atmosphere at 600° C. for 1 minute through a rapid thermal annealing furnace;

[0039] 2) a first Ga.sub.2O.sub.3 thin film 31 was grown by sputtering through magnetron sputtering with a power of 140 W, a substrate rotation speed of 20 rmp, and a pressure of 5 mtorr under argon conditions, the sputtering preferably lasted for 10 minutes, and a thickness of the first Ga.sub.2O.sub.3 thin film was 15 nm;

[0040] 3) a doped thin film 4 was grown by sputtering through magnetron sputtering with a power of 100 W, a substrate rotation speed of 20 rmp, and a pressure of 5 mtorr under argon conditions, and the doped thin film 4 was an Ag thin film with a thickness of 7 nm;

[0041] 4) a second Ga.sub.2O.sub.3 thin film 32 was grown by sputtering through magnetron sputtering with a power of 140 W, a substrate rotation speed of 20 rmp, and a pressure of 5 mtorr under argon conditions, the sputtering preferably lasted for 10 minutes, and a thickness of the second Ga.sub.2O.sub.3 thin film was 15 nm; and

[0042] 5) the grown thin films were integrally annealed in a nitrogen-oxygen atmosphere at 600° C. for 1 minute through a rapid thermal annealing furnace, and a metal-doped Ga.sub.2O.sub.3 thin film 5 shown in FIG. 2 was formed by infiltration, diffusion, and fusion between thin film materials. Specifically, the contact layer thin film 2, the first Ga.sub.2O.sub.3 thin film 31, the doped thin film 4, and the second Ga.sub.2O.sub.3 thin film 32 were fused into the metal-doped Ga.sub.2O.sub.3 thin film 5. The metal-doped Ga.sub.2O.sub.3 thin film 5 had a thickness of 47 nm.

[0043] A transmittance of the sample in Embodiment 1 was measured with an ellipsometer to obtain a curve graph of the transmittance in FIG. 3. In FIG. 3, an x-coordinate is the wavelength, and a y-coordinate is the transmittance. The 90 nm ITO is an ITO thin film with a thickness of 90 nm, which is formed by conventional electron beam evaporation and deposition, and an ITO-Ga.sub.2O.sub.3—Ag—Ga.sub.2O.sub.3 thin film is the sample prepared in Embodiment 1. It can be seen from FIG. 3 that the transmittance of the sample in the embodiment is much higher than that of the conventional 90 nm ITO thin film in a waveband range of 300 nm to 500 nm.

[0044] Table 1 shows transmittance and square resistance parameters of the new metal-doped Ga.sub.2O.sub.3 thin film 5 with the ITO as the contact layer thin film 2 and the 90 nm ITO thin film at 365 nm in Embodiment 1, and the square resistance is measured with a four-probe tester. The square resistance of the novel metal-doped Ga.sub.2O.sub.3 thin film 5 in the embodiment is much lower than that of the conventional 90 nm ITO thin film.

TABLE-US-00001 TABLE 1 365 nm 90 nm ITO ITO-M-Ga.sub.2O.sub.3 Transmittance 78.03% 92.68% Square resistance 45.03 Ω/sq 20.1 Ω/sq

[0045] The square resistance of the ultraviolet waveband Ga.sub.2O.sub.3 transparent conductive thin film of the present invention is reduced to 20 Ω/sq, the transmittance at a waveband of 365 nm is over 92%, and the specific contact resistivity between the thin film and the p-GaN surface is 10.sup.−3 Ωcm.sup.2. Since the ITO is used as the contact layer, and the doped thin film 4 is added, an overall ohmic contact characteristic of the thin film is improved. Meanwhile, due to a high transmittance of the Ga.sub.2O.sub.3 thin film in the ultraviolet waveband, the overall high transmittance of the thin film is ensured.

[0046] Compared with an ITO transparent conductive thin film, the transparent conductive thin film of the present invention has a higher thin film optical transmittance and a lower thin film square resistance. According to the present invention, conventional magnetron sputtering device and electron beam evaporation device are used to deposit each thin film, and new device does not need to be introduced into the original device, so that a process difficulty will not be increased.

[0047] The Ga.sub.2O.sub.3 transparent conductive thin film for ultraviolet waveband of the present invention combines the contact layer thin film with a better conductivity and the Ga.sub.2O.sub.3 thin film with a higher transmittance, which is beneficial for improving the transmittance of the thin film in the ultraviolet waveband and reducing the square resistance by overcoming problems of a poor contact characteristic and a low conductivity of an existing Ga.sub.2O.sub.3 thin film in the ultraviolet waveband.

Embodiment 2

[0048] A preparation method for a metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband included the following steps:

[0049] 1) a contact layer thin film 2 was conventionally grown on a substrate 1 respectively washed with sulfuric acid, hydrogen peroxide, and ammonia water in a water bath at 60° C. using an electron beam first, the contact layer thin film 2 was Ni, with a thickness of 4 nm, and was annealed in a nitrogen-oxygen atmosphere at 600° C. for 1 minute through a rapid thermal annealing furnace;

[0050] 2) a first Ga.sub.2O.sub.3 thin film 31 was grown by sputtering through magnetron sputtering with a power of 140 W, a substrate rotation speed of 20 rmp, and a pressure of 5 mtorr under argon conditions, the sputtering preferably lasted for 10 minutes, and a thickness of the first Ga.sub.2O.sub.3 thin film was 15 nm;

[0051] 3) a doped thin film 4 was grown by sputtering through magnetron sputtering with a power of 100 W, a substrate rotation speed of 20 rmp, and a pressure of 5 mtorr under argon conditions, and the doped thin film 4 was an Ag thin film with a thickness of 7 nm;

[0052] 4) a second Ga.sub.2O.sub.3 thin film 32 was grown by sputtering through magnetron sputtering with a power of 140 W, a substrate rotation speed of 20 rmp, and a pressure of 5 mtorr under argon conditions, the sputtering preferably lasted for 10 minutes, and a thickness of the second Ga.sub.2O.sub.3 thin film was 15 nm; and

[0053] 5) the grown thin films were integrally annealed in a nitrogen-oxygen atmosphere at 600° C. for 1 minute through a rapid thermal annealing furnace, and a metal-doped Ga.sub.2O.sub.3 thin film 5 shown in FIG. 2 was formed by infiltration, diffusion, and fusion between thin film materials. Specifically, the contact layer thin film 2, the first Ga.sub.2O.sub.3 thin film 31, the doped thin film 4, and the second Ga.sub.2O.sub.3 thin film 32 were fused into the metal-doped Ga.sub.2O.sub.3 thin film 5. The metal-doped Ga.sub.2O.sub.3 thin film 5 had a thickness of 41 nm.

[0054] The square resistance of the ultraviolet waveband Ga.sub.2O.sub.3 transparent conductive thin film in Embodiment 2 is reduced to 16 Ω/sq, the transmittance at a waveband of 365 nm is over 93%, and the contact characteristic between the thin film and the p-GaN surface is 0.5×10.sup.−3 Ωcm.sup.2.

Embodiment 3

[0055] A preparation method for a metal-doped gallium oxide transparent conductive thin film for ultraviolet waveband included the following steps:

[0056] 1) a contact layer thin film 2 was conventionally grown on a substrate 1 respectively washed with sulfuric acid, hydrogen peroxide, and ammonia water in a water bath at 60° C. using an electron beam first, the contact layer thin film 2 was ITO, with a thickness of 10 nm, and was annealed in a nitrogen-oxygen atmosphere at 600° C. for 1 minute through a rapid thermal annealing furnace;

[0057] 2) a first Ga.sub.2O.sub.3 thin film 31 was grown by sputtering through magnetron sputtering with a power of 140 W, a substrate rotation speed of 20 rmp, and a pressure of 5 mtorr under argon conditions, the sputtering preferably lasted for 10 minutes, and a thickness of the first Ga.sub.2O.sub.3 thin film was 10 nm;

[0058] 3) a doped thin film 4 was grown by sputtering through magnetron sputtering with a power of 100 W, a substrate rotation speed of 20 rmp, and a pressure of 5 mtorr under argon conditions, and the doped thin film 4 was an Ag thin film with a thickness of 7 nm;

[0059] 4) a second Ga.sub.2O.sub.3 thin film 32 was grown by sputtering through magnetron sputtering with a power of 140 W, a substrate rotation speed of 20 rmp, and a pressure of 5 mtorr under argon conditions, the sputtering preferably lasted for 10 minutes, and a thickness of the second Ga.sub.2O.sub.3 thin film was 10 nm; and

[0060] 5) the grown thin films were integrally annealed in a nitrogen-oxygen atmosphere at 600° C. for 1 minute through a rapid thermal annealing furnace, and a metal-doped Ga.sub.2O.sub.3 thin film 5 shown in FIG. 2 was formed by infiltration, diffusion, and fusion between thin film materials. Specifically, the contact layer thin film 2, the first Ga.sub.2O.sub.3 thin film 31, the doped thin film 4, and the second Ga.sub.2O.sub.3 thin film 32 were fused into the metal-doped Ga.sub.2O.sub.3 thin film 5. The metal-doped Ga.sub.2O.sub.3 thin film 5 had a thickness of 37 nm.

[0061] The square resistance of the ultraviolet waveband Ga.sub.2O.sub.3 transparent conductive thin film in Embodiment 2 is reduced to 20 Ω/sq, the transmittance at a waveband of 365 nm is over 94%, and the contact characteristic between the thin film and the p-GaN surface is 10.sup.−3 Ωcm.sup.2.

[0062] It should be noted that the embodiments do not constitute any restrictions on the present invention. Apparently, after understanding the contents and principles of the present invention, those skilled in the art can make various modifications and changes in forms and details without departing from the principles and scope of the present invention. These modifications and changes based on the present invention are still within the scope of protection claimed by the present invention.