An optimization calculation method for the absorption coefficient of semiconductor thin film materials grown on a transparent substrate

Abstract

The present invention discloses an optimization calculation method for the absorption coefficient of a semiconductor thin film material grown on a transparent substrate. The calculation process includes the following steps: first, the ultraviolet-visible absorption spectrum and reflection spectrum of the semiconductor electrode are tested by a UV-visible spectrophotometer, and then the measured absorption value is corrected by the reflection spectrum. Next, the absorption value is subjected to Min-Max standardization to make it more realistic, and finally the absorption coefficient of the pure semiconductor film is derived using the relationship between the absorption coefficient and the absorption value. The present invention mainly optimizes the calculation of the absorption coefficient of a pure semiconductor film by using the UV-visible absorption spectrum and the reflection spectrum, and proposes a method for calculating the absorption coefficient of a pure semiconductor film. This method can be applied to any semiconductor thin film electrode, and provides a basis for accurately calculating the absorption coefficient of the semiconductor film.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor thin films, and in particular relates to an optimization calculation method for the absorption coefficient of a semiconductor thin film material grown on a transparent substrate. Background Art

[0002] Among many photocatalytic and photoelectrocatalytic systems, thin-film semiconductor photoelectrode materials grown on transparent substrates have been widely used. The light absorption performance of semiconductor materials is one of the most important factors affecting their photocatalytic and photoelectrocatalytic performance, so it is of great significance to accurately measure the light absorption coefficient of thin-film semiconductor materials.

[0003] For thin film semiconductor materials grown on transparent substrates, the difficulty in accurately measuring their absorption coefficients lies in the reflection of light by the semiconductor film and the absorption and reflection of light by the transparent substrate. Therefore, the present invention optimizes the method for calculating the absorption coefficient of pure semiconductor films at different wavelengths by combining the test results of the ultraviolet-visible absorption spectrum and reflection spectrum of the transparent substrate and the thin film semiconductor material grown on the transparent substrate. Summary of the invention

[0004] The purpose of the present invention is to provide a method for optimizing the calculation of the absorption coefficient of a semiconductor thin film material grown on a transparent substrate, and to optimize the calculation of the absorption coefficient of the semiconductor thin film through the test results of the ultraviolet-visible absorption spectrum and the reflection spectrum.

[0005] The technical solution provided by the present invention is: a method for optimizing the calculation of the absorption coefficient of a semiconductor thin film material grown on a transparent substrate, characterized in that it comprises the following steps:

[0006] Step 1: Use a UV-visible spectrophotometer to test the UV-visible absorption spectrum and reflection spectrum of the semiconductor electrode to obtain the absorption value A 测 and R;

[0007] Step 2: Use the R obtained from the reflectance spectrum test to measure the absorption value A measured in step 1 测 make corrections;

[0008] Step 3: Corrected absorption value A 修 Perform Min-Max normalization to obtain A * ;

[0009] Step 4: Using the absorption coefficient and absorption value A * The absorption coefficient of the semiconductor film is derived from the relationship between

[0010] Furthermore, the above-mentioned method for optimizing the calculation of the absorption coefficient of a semiconductor thin film material grown on a transparent substrate is characterized in that the absorption value described in step 1 is:

[0011]

[0012] Among them, I0 is the incident light intensity, I t is the intensity of transmitted light.

[0013] Furthermore, the above-mentioned method for optimizing the calculation of the absorption coefficient of a semiconductor thin film material grown on a transparent substrate is characterized in that the correction formula of the absorption value in step 2 is as follows:

[0014]

[0015] Where R% is the reflectivity, I R The intensity of reflected light.

[0016] Furthermore, the above-mentioned method for optimizing the calculation of the absorption coefficient of a semiconductor thin film material grown on a transparent substrate is characterized in that the Min-Max normalization process of the corrected absorption value in step 3 is as follows:

[0017]

[0018] Among them, A * is the standardized absorbance value corresponding to different wavelengths, A max is the maximum value among all corrected absorption values, A min is the minimum value among all corrected absorption values.

[0019] Furthermore, the above-mentioned method for optimizing the calculation of the absorption coefficient of a semiconductor thin film material grown on a transparent substrate is characterized in that the calculation formula of the absorption coefficient in step 4 is as follows:

[0020] I t =(I0-I R )·e -αl ;

[0021] Deformed: Taking the logarithm of both sides gives: A 修 =αl·lge;

[0022] Among them, α is the absorption coefficient, l is the thickness of the semiconductor film; due to the actual process of A 修 Min-Max normalization was performed, so at this time The beneficial effects of the present invention are:

[0023] 1. The present invention proposes an optimization calculation method for the absorption coefficient of a semiconductor thin film material grown on a transparent substrate. The calculation process is simple and feasible, and the absorption coefficient value obtained is more accurate.

[0024] 2. The application scope of the present invention is very wide. In theory, it can be applied to any thin-film semiconductor photoelectrode material grown on a transparent substrate, providing a basis for calculating the absorption coefficient of the semiconductor film. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1a This is a planar SEM image of the FTO / BiVO4 photoelectrode prepared in the present invention.

[0026] Figure 1b This is a cross-sectional SEM image of the FTO / BiVO4 photoelectrode prepared in the present invention.

[0027] Figure 2a The UV-visible absorption spectra of FTO and FTO / BiVO4 photoelectrodes measured in the present invention.

[0028] Figure 2b The UV-visible reflection spectra of FTO and FTO / BiVO4 photoelectrodes measured in the present invention.

[0029] Figure 2c These are the corrected absorption values ​​of the FTO and FTO / BiVO4 photoelectrodes prepared in the present invention.

[0030] Figure 2d is the absorption value of the pure BiVO4 film prepared in the present invention.

[0031] Figure 2e It is the absorption value of the pure BiVO4 film prepared in the present invention after Min-Max standardization.

[0032] Figure 2f is the absorption coefficient of the pure BiVO4 film prepared in the present invention. DETAILED DESCRIPTION

[0033] The present invention is further explained below in conjunction with specific implementation schemes, but is not intended to limit the protection scope of the present invention.

[0034] In order to obtain an optimized calculation method for the absorption coefficient of semiconductor thin film materials grown on a transparent substrate, the present invention takes FTO / BiVO4 electrode as an example, optimizes and calculates the absorption coefficient of pure BiVO4 through the test results of ultraviolet-visible absorption spectrum and reflection spectrum, and provides an optimized calculation method for the absorption coefficient of semiconductor thin film materials grown on a transparent substrate. The technical solution is as follows:

[0035] According to Lambert-Beer's law:

[0036]

[0037] In fact, when a beam of light hits a semiconductor electrode, it will go through the processes of transmission, reflection, refraction, scattering and absorption. Here we ignore the refraction and scattering. The actual measured absorption value includes the real absorption and reflection, so I0 here should be I0-I R ,Right now

[0038]

[0039] In addition, the calculation formula of reflectivity is as follows:

[0040]

[0041] Substituting equation (3) into equation (2) and combining it with equation (1), we can obtain:

[0042] A 修 =lg(1-R%)+A 测 (4)

[0043] (4) is the corrected absorption value. In the actual test process, we tested the absorption values ​​of FTO and FTO / BiVO4 in the wavelength range of 350nm-650nm under positive and negative light respectively. 测 And the reflectivity R, such as Figure 2a and 2b Table 1 shows the absorption and reflectivity of FTO and FTO / BiVO4 at 450nm when they are illuminated directly, taking this as an example for calculation.

[0044] Table 1 Absorption and reflectivity of FTO and FTO / BiVO4 at 450nm under direct light

[0045]

[0046] Using formula (3), the FTO absorption value is corrected: A FTO =lg(1-12.089 / 100)+0.109=0.05304FTO / BiVO4 absorption value correction: A FTO / BiVO4 =lg(1-7.874 / 100)+2.301=2.26538 All the absorption values ​​of FTO and FTO / BiVO4 are corrected respectively. The corrected results are as follows Figure 2c As shown. Then, to obtain the absorption value of pure BiVO4, it is necessary to subtract the absorption value of FTO from the absorption value of FTO / BiVO4, that is, 2.26538-0.05304=2.21234, which is the absorption value of pure BiVO4. Subtract the corrected absorption value of FTO from the corrected absorption value of FTO / BiVO4 at all wavelengths to obtain the absorption value of pure BiVO4 at all wavelengths, as shown in Figure 2d shown.

[0047] from Figure 2a It can be seen that BiVO4 still has a certain absorption in the long-wave region, which is caused by the scattering of BiVO4, not the real absorption of BiVO4. In the short-wave region, the absorption value of BiVO4 is larger, and we approximately assume that no scattering occurs. Therefore, the absorption value in the long-wave region needs to be standardized. Here we use Min-Max standardization:

[0048]

[0049] For example, under normal illumination conditions, among all wavelengths of pure BiVO4 corrected absorption values, the maximum value is 2.28014 and the minimum value is 0.2296. By analogy, the standardized absorption value is Figure 2e As shown, the absorption value Min-Max in the long-wave region is standardized on the premise that the absorption value in the short-wave region does not change, so as to make it more consistent with the facts.

[0050] Finally, substitute the standardized absorption value into (where l is the thickness of the semiconductor film. As can be seen from Figure 1, the thickness of the prepared BiVO4 film is about 1.5 μm). The same is true for other wavelengths. The absorption coefficient of pure BiVO4 is as follows: Figure 2f As shown in Figure 2, the absorption coefficient of pure BiVO4 is close to that of pure BiVO4 under both positive and backlight conditions, which is consistent with the facts.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for optimizing the calculation of the absorption coefficient of a semiconductor thin film material grown on a transparent substrate, characterized in that: The steps include: Step 1: Use a UV-visible spectrophotometer to measure the UV-visible absorption spectrum and reflectance spectrum of the semiconductor electrode to obtain the absorption value A 测 and reflectivity R ; Step 2: Using reflectance spectroscopy to test R The absorbance value measured in step 1 A 测 make corrections; Step 3: Corrected absorption value A 修 Min-Max normalization is performed to obtain A * ; Step 4: Using the absorption coefficient and absorption value A * The absorption coefficient of the semiconductor film is derived from the relationship between The correction formula of the absorption value in step 2 is as follows: A 修 = = lg (1-R%) + A 测 ； in, R% is the reflectivity, R % = ，I R is the intensity of reflected light; The calculation formula of the absorption coefficient in step 4 is as follows: = · ； Deformed: , taking the logarithm of both sides, we get: ,Right now A 修 = ； in, α is the absorption coefficient, l is the thickness of the semiconductor film; due to the actual process A 修 After Min-Max normalization, the absorption coefficient is .

2. The method for optimizing the calculation of the absorption coefficient of a semiconductor thin film material grown on a transparent substrate according to claim 1, characterized in that: The absorption value described in step 1 is: A 测 = ； in, I 0 is the incident light intensity, I t is the intensity of transmitted light.

3. The method for optimizing the calculation of the absorption coefficient of a semiconductor thin film material grown on a transparent substrate according to claim 1, characterized in that: The Min-Max standardization process of the corrected absorbance value in step 3 is as follows: ； in, A * is the standardized absorbance value corresponding to different wavelengths, A max is the maximum value among all corrected absorption values, A min is the minimum value among all corrected absorption values.

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