CN116072744B - A method for improving the ultraviolet detection performance of diamond using localized surface plasmon resonance of indium nanoparticles - Google Patents

Abstract

A method for improving the ultraviolet detection performance of diamond by using localized surface plasmon resonance of indium nanoparticles. The purpose of the present invention is to improve the spectral response rate of diamond ultraviolet detectors. Method for improving the ultraviolet detection performance of diamond: 1. Immerse intrinsic single crystal diamond in mixed acid and heat it to obtain diamond with oxygen terminals; 2. Clean the sample; 3. Use magnetron sputtering to sputter titanium layer and gold layer on the surface of the cleaned diamond in sequence to form interdigitated electrodes, and anneal to obtain ohmic contact diamond; 4. Set an anodized aluminum mask on the surface of the ohmic contact diamond, and plate indium nano-islands on the ohmic contact diamond surface by thermally evaporating indium. The present invention uses localized surface plasmon resonance of indium nanoparticles to enhance the spectral response rate of diamond ultraviolet detection, expands the way to enhance the ultraviolet detection performance of diamond, and makes the diamond ultraviolet detector closer to the "5S" standard recognized by the industry.

Description

A method for improving diamond ultraviolet detection performance by using localized surface plasmon resonance of indium nanoparticles

Technical Field

The invention relates to a method for improving the diamond ultraviolet detection spectrum response rate by using indium nanoparticle localized surface plasmon resonance.

Background Art

Ultraviolet detection has attracted much attention due to its important applications in fire detection, ozone monitoring and satellite communications. High-performance photon detectors usually need to meet the "5S" standard, namely high sensitivity, high signal-to-noise ratio, high spectral selectivity, high response speed and high stability. Diamond is known as the ultimate semiconductor and is considered to be the ideal material for photon detectors that are most likely to meet the "5S" standard due to its excellent physical and chemical properties, such as wide ^bandgap ( ^5.47eV ), high carrier mobility (electron mobility is about 2000cm2V ^{- 1s} - ¹ , hole mobility is about 1700cm2V ^- 1s ^-1 ), high thermal conductivity (22Wcm ^- 1K ^-1 ), high breakdown field strength (greater than 10MVcm-1) and high carrier saturation velocity (electrons are about 9.6× ^106cms - ¹ , holes are about 1.4× ^107cms - ¹ ). In recent years, researchers have been committed to improving the performance of diamond UV detectors by adopting different device structure designs and using diamond substrates with higher material quality, and have achieved remarkable results. In addition, since the localized surface plasmon resonance of metal nanoparticles can enhance the local electric field and semiconductor light absorption, using metal nanoparticles whose localized surface plasmon resonance band is in the deep ultraviolet range to enhance diamond UV absorption can be an effective solution to improve the performance of diamond UV detectors.

Summary of the invention

The purpose of the present invention is to improve the response rate of the diamond ultraviolet detector spectrum and to provide a method for improving the ultraviolet detection performance of diamond by using the localized surface plasmon resonance of indium nanoparticles.

The method of improving the ultraviolet detection performance of diamond by using localized surface plasmon resonance of indium nanoparticles is implemented by the following steps:

1. Acid-boiled samples:

The autoclave is filled with mixed acid, the intrinsic single crystal diamond is immersed in the mixed acid, and heated at a high temperature of 120°C to 160°C for 2 to 4 hours to obtain diamond with oxygen terminals;

2. Sample cleaning:

The diamond with oxygen terminal is ultrasonically cleaned by using acetone, anhydrous ethanol and deionized water in sequence to obtain the cleaned diamond;

3. Preparation of Ohmic Contact Electrode:

A titanium layer and a gold layer are sequentially sputtered on the cleaned diamond surface by magnetron sputtering to form interdigital electrodes, and then annealing is performed at 400-600°C under a vacuum degree of less than 8×10 ^-4 Pa to obtain ohmic contact diamond;

4. Preparation of Indium Nanoparticles on Diamond Surface:

An anodized aluminum mask is set on the surface of the ohmic contact diamond, and a through hole is opened in the anodized aluminum mask. Indium nano-islands are plated on the ohmic contact diamond surface by thermal evaporation of indium, thereby improving the ultraviolet detection performance of diamond through localized surface plasmon resonance of indium nanoparticles.

The local surface plasmon resonance band of indium overlaps with the corresponding band of the diamond ultraviolet response peak. Under ultraviolet light excitation, conduction electron oscillation occurs in the indium nanoparticles, capturing light around the surface of the nanoparticles, resulting in an enhancement of the local electric field, thereby enhancing the light absorption of diamond. Under this drive, the diamond excitons and plasmons interact with each other, resulting in an increase in the ultraviolet spectrum response rate. The enhancement effect of indium nanoparticles is more significant than that of other metal particles (such as aluminum nanoparticles and iridium nanoparticles). In addition, indium is relatively cheap, has a low melting point, is convenient for evaporation technology, and has good stability at room temperature. Therefore, the present invention adopts indium nanoparticles local surface plasmon resonance to enhance the diamond ultraviolet detection spectrum response rate.

The method of improving the ultraviolet detection performance of diamond by using localized surface plasmon resonance of indium nanoparticles in the present invention has the following beneficial effects:

1. There is no need to perform mechanical processing on the diamond material, which simplifies the device preparation process, ensures that the diamond material is not damaged to the greatest extent, and is more conducive to the advantages of diamond materials in device performance.

2. Indium is relatively cheap, has a low melting point, is convenient for evaporation process, and has good stability at room temperature.

3. Expanded the ways to enhance the performance of diamond UV detection, making diamond UV detectors closer to the industry-recognized "5S" standard.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a scanning electron microscope image of the surface of the diamond UV detector in the embodiment at different magnifications, wherein (a) represents a magnification of 70,000×, and (b) represents a magnification of 50,000×;

FIG2 is a test graph of the spectral response rate of the diamond ultraviolet detector obtained in the embodiment and the comparative embodiment, wherein the upper curve represents the embodiment and the lower curve represents the comparative embodiment;

Figure 3 is a dark current and photocurrent curve of the diamond UV detector obtained in the embodiment and the comparative embodiment under 215nm light illumination, wherein 1 represents the photocurrent of the embodiment, 2 represents the photocurrent of the comparative embodiment, 3 represents the dark current of the embodiment, and 4 represents the dark current of the comparative embodiment.

DETAILED DESCRIPTION

Specific implementation method 1: This implementation method uses indium nanoparticle localized surface plasmon resonance to improve the ultraviolet detection performance of diamond according to the following steps:

1. Acid-boiled samples:

The autoclave is filled with mixed acid, the intrinsic single crystal diamond is immersed in the mixed acid, and heated at a high temperature of 120°C to 160°C for 2 to 4 hours to obtain diamond with oxygen terminals;

2. Sample cleaning:

The diamond with oxygen terminal is ultrasonically cleaned by using acetone, anhydrous ethanol and deionized water in sequence to obtain the cleaned diamond;

3. Preparation of Ohmic Contact Electrode:

A titanium layer and a gold layer are sequentially sputtered on the cleaned diamond surface by magnetron sputtering to form interdigital electrodes, and then annealing is performed at 400-600°C under a vacuum degree of less than 8×10 ^-4 Pa to obtain ohmic contact diamond;

4. Preparation of Indium Nanoparticles on Diamond Surface:

An anodized aluminum mask is set on the surface of the ohmic contact diamond, and a through hole is opened in the anodized aluminum mask. Indium nano-islands are plated on the ohmic contact diamond surface by thermal evaporation of indium, thereby improving the ultraviolet detection performance of diamond through localized surface plasmon resonance of indium nanoparticles.

In this embodiment, a plurality of indium nanoparticles are plated on the surface of the diamond photon detector, and the diamond ultraviolet light absorption is enhanced through the effect of the localized surface plasmon resonance of the indium nanoparticles, thereby enhancing the spectral response rate of the diamond ultraviolet detector.

Specific implementation method 2: This implementation method is different from specific implementation method 1 in that the mixed acid in step 1 is composed of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1.

In this embodiment, the mass concentration of concentrated sulfuric acid is 98%, and the mass concentration of concentrated nitric acid is 68%.

Specific implementation method three: This implementation method is different from specific implementation methods one or two in that in step one, heating is performed at a high temperature of 150° C. for 2 hours.

Specific implementation method 4: The difference between this implementation method and specific implementation methods 1 to 3 is that the ultrasonic cleaning time in step 2 is 15 to 30 minutes each time.

Specific implementation mode 5: This implementation mode is different from any one of specific implementation modes 1 to 4 in that the thickness of the sputtered titanium layer in step 3 is 20 to 30 nm, and the thickness of the gold layer is 30 to 50 nm.

Specific implementation example 6: This implementation example is different from specific implementation example 5 in that the thickness of the sputtered titanium layer in step 3 is 20 nm, and the thickness of the gold layer is 30 nm.

Specific implementation example 7: This implementation example is different from specific implementation examples 1 to 5 in that the interdigitated electrode in step 3 has 6 to 10 electrodes, and the finger width is 100 to 150 μm.

Specific embodiment eight: This embodiment differs from any one of specific embodiments one to six in that in step three, an annealing treatment is performed at 500° C. for 30 minutes.

Specific embodiment 9: This embodiment is different from any one of specific embodiments 1 to 7 in that the process of thermal evaporation of indium in step 4 is to place the single substance indium into an electron beam evaporation device (EB) and control the heating current to be 46-52A.

Specific embodiment ten: This embodiment is different from specific embodiments one to seven in that the diameter of the indium nano-islands in step four is 20 to 30 nm.

Embodiment: The method of improving the ultraviolet detection performance of diamond by using localized surface plasmon resonance of indium nanoparticles in this embodiment is implemented according to the following steps:

1. Acid-boiled samples:

The autoclave is filled with mixed acid, and the intrinsic single crystal diamond is immersed in the mixed acid, which is concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1, and heated at 150°C for 2 hours to obtain diamond with oxygen termination;

2. Sample cleaning:

The diamond with oxygen terminal is ultrasonically cleaned by acetone, anhydrous ethanol and deionized water in sequence, the power of ultrasonic cleaning is 100W, the cleaning time is 15 minutes, and the cleaned diamond is obtained;

3. Preparation of Ohmic Contact Electrode:

A titanium layer with a thickness of 20 nm and a gold layer with a thickness of 30 nm were sequentially sputtered on the cleaned diamond surface by magnetron sputtering to form an interdigitated electrode structure, which has 10 electrodes (5 interdigitated electrodes on one side), with an interval of 80 μm and a finger width of 120 μm. Then, an annealing treatment was performed at 500°C for 30 minutes under a vacuum degree of less than 8×10 ^-4 Pa to obtain an ohmic contact diamond.

4. Preparation of Indium Nanoparticles on Diamond Surface:

An anodized aluminum mask is set on the surface of the ohmic contact diamond. The anodized aluminum mask is provided with through holes (the through hole diameter is 20 to 30 nm). Indium nano-islands are plated on the ohmic contact diamond surface by thermal evaporation of indium. The diameter of the indium nano-islands is 20 to 30 nm, thereby improving the ultraviolet detection performance of diamond through the localized surface plasmon resonance of indium nanoparticles.

In this embodiment, the intrinsic single crystal diamond sample was purchased from Element Six, and is an optical grade CVD single crystal diamond with dimensions of 3 mm × 3 mm × 0.25 mm, roughness of double-sided polishing, Ra < 30 nm, boron impurity concentration < 0.05 ppm, and nitrogen impurity concentration < 1 ppm.

Comparative Example: This example is different from Example 1 in that step 4 of the diamond surface indium nanoparticle preparation process is not performed.

Characterization and testing: A scanning electron microscope was used to characterize the surface of the detector in the experimental group to confirm whether the indium nano-islands were successfully plated; and the ultraviolet detection spectral response rates of the diamond ultraviolet detectors of the embodiment and the comparative embodiment were characterized and compared.

As shown in FIG1 , indium nano-islands with a diameter of 20 to 30 nm and almost uniform size can be clearly observed. As shown in FIG2 , at the measured wavelength, the spectral response rate of the detector of the embodiment is higher than that of the detector of the comparative experimental group as a whole, especially in the deep ultraviolet region, the contrast is very obvious. Under 215nm illumination, the spectral response rate of the detector of the embodiment and the comparative embodiment is most obvious, achieving a leap of 2 orders of magnitude. Under 215nm illumination, the response rate of the detector of the embodiment is about 2.94×10 _– ³ A/W at 20V bias. Under 500nm illumination, the spectral response rates of the detectors of the embodiment and the comparative embodiment are relatively close, from which it can be obtained that the ultraviolet/visible light (215nm/500nm) suppression ratio of the embodiment is significantly enhanced compared to that of the detector of the comparative embodiment. As shown in FIG3 , the dark currents of the two detectors are almost the same, and the photocurrent enhancement is very obvious. Under 215nm illumination, the current of the detector of the embodiment reaches 1.12×10 _– ⁹ A at 20V bias.

Claims (6)

1. The method for improving the ultraviolet detection performance of the diamond by adopting indium nanoparticle localized surface plasmon resonance is characterized by comprising the following steps of:

1. Acid-boiled sample:

The autoclave is filled with mixed acid, the intrinsic single crystal diamond is immersed in the mixed acid, and the diamond with an oxygen terminal is obtained by heating for 2-4 hours at the high temperature of 120-160 ℃;

2. sample cleaning:

sequentially carrying out ultrasonic cleaning on the diamond with the oxygen terminal by adopting acetone, absolute ethyl alcohol and deionized water to obtain cleaned diamond;

3. Ohmic contact electrode preparation:

Sputtering a titanium layer and a gold layer on the surface of the cleaned diamond in sequence by adopting a magnetron sputtering method to form an interdigital electrode, wherein the thickness of the sputtered titanium layer is 20 nm, the thickness of the gold layer is 30 nm, and then annealing treatment is carried out at 400-600 ℃ under the vacuum degree of less than 8 multiplied by 10 ⁻⁴ Pa to obtain the diamond with ohmic contact;

4. preparing diamond surface indium nano particles:

An anodic aluminum oxide mask is arranged on the surface of the ohmic contact diamond, a through hole is formed in the anodic aluminum oxide mask, indium nanometer islands are plated on the ohmic contact diamond surface through indium thermal evaporation, the diameter of each indium nanometer island is 20-30 nm, and therefore the ultraviolet detection performance of the diamond is improved through indium nanometer particle local surface plasmon resonance;

Wherein the interdigital electrode in the third step has 6-10 interdigital electrodes with a finger width of 100-150 μm.

2. The method for improving ultraviolet detection performance of diamond by adopting indium nanoparticle localized surface plasmon resonance according to claim 1, wherein in the first step, the mixed acid is prepared from the following components in a volume ratio of 3:1 and concentrated nitric acid.

3. The method for improving ultraviolet detection performance of diamond by using indium nanoparticle localized surface plasmon resonance according to claim 1, wherein in the first step, heating is performed at a high temperature of 150 ℃ for 2 hours.

4. The method for improving the ultraviolet detection performance of the diamond by adopting indium nanoparticle localized surface plasmon resonance according to claim 1, wherein the ultrasonic cleaning time in the second step is 15-30 minutes each time.

5. The method for improving ultraviolet detection performance of diamond by adopting indium nanoparticle localized surface plasmon resonance according to claim 1, wherein in the third step, annealing treatment is performed at 500 ℃ for 30 minutes.

6. The method for improving ultraviolet detection performance of diamond by adopting indium nanoparticle localized surface plasmon resonance according to claim 1, wherein the process of thermally evaporating indium in the fourth step is to put elemental indium into electron beam evaporation equipment, and control heating current to be 46-52A.