Substrate treatment and antimony layer evaporation method for improving sensitivity of reflective photoelectric cathode

Abstract

The invention relates to the field of photomultipliers, and discloses a substrate treatment and antimony layer evaporation method for improving the sensitivity of a reflection-type photoelectric cathode, and the method comprises the following steps: S1, carrying out the pre-cleaning treatment of a cathode substrate through an alkaline cleaning solution; s2, carrying out physical polishing treatment on the pre-cleaned cathode substrate by adopting a polishing device; s3, performing electrochemical polishing treatment on the polished cathode substrate; s4, evaporating an aluminum layer on the polished cathode substrate; and S5, evaporating an antimony layer on the aluminum layer. Through physical and electrochemical polishing surface treatment and aluminum layer evaporation, the sensitivity of the photoelectric cathode is remarkably improved, the aluminum layer serves as a high-reflectivity middle layer, the reflectivity of incident light is further enhanced, more light energy is effectively converted into electric signals, and therefore the overall photoelectric conversion efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of photomultiplier tubes, in particular to a substrate processing and antimony layer evaporation method for improving the sensitivity of a reflective photocathode. Background Art

[0002] Photomultiplier tubes are vacuum electronic devices that can convert weak light signals into electrical signals and amplify them. They have the characteristics of high gain and fast response, and are widely and importantly used in the fields of spectral analysis, biological detection, and radiation detection. As the most important component of a photomultiplier tube, the photocathode converts the received photons into electrons through the external photoelectric effect for amplification and processing. The reflective photocathode is one of the types of cathodes for photomultiplier tubes, and is usually used in side-window photomultiplier tubes and is prepared on the surface of a metal nickel substrate with good conductivity.

[0003] The traditional method of improving the sensitivity of reflective photocathode focuses on controlling the thickness of the antimony layer and the amount of alkali metal evaporation, which cannot effectively improve the crystallinity of the photocathode film, resulting in low cathode sensitivity. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a substrate treatment and antimony layer evaporation method for improving the sensitivity of the reflective photocathode, which solves the shortcomings of the traditional reflective photocathode in photoelectric conversion efficiency and surface uniformity. By optimizing the substrate treatment and antimony layer evaporation method, the sensitivity and reflectivity of the photocathode are significantly improved.

[0005] To achieve the above objectives, the present invention is implemented by the following technical scheme: a substrate treatment and antimony layer evaporation method for improving the sensitivity of a reflective photocathode, comprising the following steps:

[0006] Pre-cleaning the cathode substrate using an alkaline cleaning solution, wherein the pH value of the alkaline cleaning solution is 9 to 14;

[0007] Using a polishing device to perform physical polishing on the pre-cleaned cathode substrate;

[0008] performing electrochemical polishing on the polished cathode substrate;

[0009] Vapor depositing an aluminum layer on the polished cathode substrate, wherein the thickness of the aluminum layer is 80 to 120 nanometers;

[0010] The antimony layer is deposited on the aluminum layer, the thickness of the antimony layer is controlled to be 800-1000 nanometers, the baking temperature is 200-220°C, and the evaporation rate is

[0011] Preferably, the cleaning temperature of the pre-cleaning treatment is 50-80° C., the cleaning time is 5-15 minutes, and the cleaning further includes rinsing with deionized water to remove residual alkaline cleaning solution.

[0012] Preferably, the physical polishing step comprises:

[0013] The barrel polishing process comprises the following steps:

[0014] Choose ceramic or resin with a diameter of 1 to 5 mm as the polishing medium;

[0015] Filling the polishing medium into the polishing tank with a filling rate of 40 to 60%;

[0016] The rolling speed of the polishing device is set to 30 to 100 rpm and the polishing time is 0.5 to 2 hours;

[0017] During the polishing process, a polishing solution is added, wherein the polishing solution comprises deionized water, ethylene glycol, citric acid, triethanolamine and an anti-foaming agent;

[0018] After polishing is completed, the polished cathode substrate is rinsed with deionized water.

[0019] Preferably, the polishing liquid comprises the following components by volume percentage:

[0020] Deionized water: 60-75%;

[0021] Ethylene glycol: 10-20%;

[0022] Citric acid: 5-10%;

[0023] Triethanolamine: 2-5%;

[0024] Antifoaming agent: 0.1~1%.

[0025] Preferably, the electrochemical polishing step comprises:

[0026] placing the cathode substrate in an electrolytic cell containing an electrolyte comprising phosphoric acid and sulfuric acid;

[0027] Applying a voltage of 5 to 15 volts and controlling a current density of 10 to 30 amperes per square decimeter;

[0028] The electrochemical polishing treatment is continued for 5 to 30 minutes at a temperature of 20 to 40°C;

[0029] After polishing, the cathode substrate was immediately removed from the electrolytic cell and rinsed with deionized water to remove residual electrolyte.

[0030] Preferably, the electrolyte comprises the following components by volume percentage:

[0031] 85% phosphoric acid: 10-30%;

[0032] 98% sulfuric acid: 5-15%;

[0033] Sodium chloride: 0.1-1%;

[0034] Anti-corrosion agent: 0.05~0.5%.

[0035] Preferably, the method further comprises cleaning the polished parts after the electrochemical polishing treatment, wherein the cleaning treatment comprises rinsing the parts with deionized water or ultrapure water at a temperature of room temperature to 40°C, drying the parts at a temperature of 50 to 70°C for 10 to 30 minutes after rinsing, and then performing a vacuum degassing treatment at 550°C with a vacuum degree of 1x10 -5 Pa, and lasts for 1 to 3 hours.

[0036] Preferably, the step of evaporating an aluminum layer on the polished cathode substrate comprises:

[0037] Place the cathode substrate after vacuum degassing in a vacuum evaporation device and draw the vacuum degree of the device to 1x10 -6 Pa;

[0038] Heating the aluminum source to its evaporation temperature, the temperature range is 810 ~ 850 ° C;

[0039] Control the aluminum evaporation rate to Perform evaporation until the thickness of the aluminum layer reaches a set value;

[0040] After the evaporation is completed, slowly cool to room temperature.

[0041] Preferably, the step of evaporating an antimony layer on the aluminum layer comprises:

[0042] The cathode substrate with the aluminum layer deposited on it is placed in a vacuum deposition device, and the vacuum degree of the device is drawn to 1x10 -6 Pa;

[0043] Heating to 200-220°C, performing antimony layer evaporation;

[0044] Heat the antimony source to its evaporation temperature, which ranges from 330 to 350°C;

[0045] The evaporation rate of antimony is controlled until the thickness of the antimony layer reaches a set value.

[0046] Preferably, the substrate is a nickel part substrate.

[0047] The invention also provides a photomultiplier tube, comprising a reflective photocathode prepared by the method.

[0048] The present invention provides a substrate treatment and antimony layer evaporation method for improving the sensitivity of a reflective photocathode, which has the following beneficial effects:

[0049] 1. The present invention significantly improves the sensitivity of the photocathode through physical and electrochemical polishing surface treatment and aluminum layer evaporation. Physical polishing reduces surface roughness, while electrochemical polishing further improves surface finish and uniformity. These improvements reduce light scattering and enhance light absorption. The aluminum layer, as a high-reflectivity intermediate layer, further enhances the reflectivity of the incident light, allowing more light energy to be effectively converted into electrical signals, thereby improving the overall photoelectric conversion efficiency.

[0050] 2. The surface treatment step of the present invention ensures the uniformity of the photocathode surface, which is achieved through physical and electrochemical polishing processes. The uniform surface not only helps to reduce the performance instability caused by defects, but also optimizes the uniform deposition of the subsequent evaporated aluminum layer and antimony layer. This surface uniformity is crucial to improving the reliability and performance of the photocathode.

[0051] 3. In the process of evaporating the antimony layer on the aluminum layer, the present invention optimizes the crystallinity of the antimony layer by precisely controlling the evaporation parameters. Excellent crystallinity not only improves the photoelectric response speed of the photocathode, but also enhances the adhesion of the antimony layer, which is crucial for the long-term stability and durability of the cathode.

[0052] 4. The present invention significantly improves the overall performance of photomultiplier tubes. Higher sensitivity and reflectivity enable photomultiplier tubes to demonstrate better performance in applications such as spectral analysis, biological detection, and radiation detection. The improved method provided by the present invention not only improves the performance of photomultiplier tubes, but also expands their application potential in low-light environments, making them an ideal choice for high-precision scientific instruments. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is a cold field emission scanning electron microscope image of the antimony layer of the present invention;

[0054] Figure 2 It is the X-ray diffraction spectrum of the antimony layer of the present invention. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] The present invention provides a substrate treatment and antimony layer evaporation method for improving the sensitivity of a reflective photocathode, comprising the following steps:

[0057] Step S1: Pre-cleaning of cathode substrate

[0058] The first step of the present invention is to pre-clean the cathode substrate by using an alkaline cleaning solution to remove oil, oxides and other contaminants on the surface of the substrate. This step is crucial for the subsequent polishing process because any remaining impurities will affect the polishing effect and the adhesion of the aluminum layer and the antimony layer.

[0059] In the present invention, an alkaline cleaning solution with a pH value of 9 to 14 is selected, which can effectively decompose and remove surface contaminants without excessively corroding the substrate material. The cleaning temperature is controlled between 50 and 80°C to accelerate the cleaning process, and the cleaning time is 5 to 15 minutes. After cleaning, deionized water is used for rinsing, and the rinsing process is performed at least 3 times to ensure that all residual cleaning solution is removed. Through the above steps, the substrate surface is fully purified, laying a good foundation for the subsequent polishing step.

[0060] Step S2: Physical polishing of cathode substrate

[0061] After the pre-cleaning treatment, physical polishing treatment is performed to further improve the surface finish of the cathode substrate. The physical polishing adopts a rolling polishing device, in which ceramics or resins with a diameter of 1 to 5 mm are selected as polishing media, and the filling rate is controlled between 40 and 60%. The rolling speed of the polishing device is set at 30 to 100 rpm, and the polishing time is 0.5 to 2 hours. Polishing liquid is added during the polishing process. The formula of the polishing liquid includes 60 to 75% deionized water, 10 to 20% ethylene glycol, 5 to 10% citric acid, 2 to 5% triethanolamine and 0.1 to 1% anti-foaming agent. This formula design can provide good lubrication during the polishing process, while effectively removing tiny surface defects.

[0062] Through tumbling polishing, the substrate surface becomes flatter and smoother, the microscopic bumps are reduced, and the surface quality of the substrate is significantly improved. This improvement not only improves the effect of subsequent electrochemical polishing, but also provides a better foundation for the uniform deposition of aluminum and antimony layers.

[0063] Step S3: Electrochemical polishing of cathode substrate

[0064] After physical polishing, electrochemical polishing is performed to further improve the surface finish and uniformity of the substrate. The substrate is placed in an electrolytic tank, and the electrolyte includes 10-30% phosphoric acid, 5-15% sulfuric acid, 0.1-1% sodium chloride and 0.05-0.5% resist. A voltage of 5-15 volts is applied, and the current density is controlled at 10-30 amperes per square decimeter. The electrochemical polishing process lasts for 5-30 minutes at a temperature of 20-40°C. After polishing is completed, the substrate is immediately rinsed with deionized water to completely remove residual electrolyte and avoid corrosion.

[0065] Electrochemical polishing removes the tiny bumps on the substrate surface evenly through electrolysis, further improving the surface smoothness. This process can significantly reduce the roughness of the substrate surface and improve the uniformity and adhesion of subsequent coatings. The addition of anti-corrosion agents effectively prevents excessive corrosion and ensures the best polishing effect.

[0066] Step S4: Evaporation of aluminum layer

[0067] After polishing, the cathode substrate was thoroughly cleaned and dried, and then vacuum degassed at 550°C to a vacuum degree of 1x10 -5 Pa for 1 to 3 hours to remove residual moisture and gas. The degassed substrate is placed in a vacuum evaporation device, and the vacuum degree of the device is evacuated to 1x10 -6 Pa. Heat the aluminum source to a temperature of 660-700°C and control the aluminum evaporation rate to The aluminum layer is evaporated until the thickness of the aluminum layer reaches 80 to 120 nanometers.

[0068] The role of the evaporated aluminum layer is to provide an intermediate layer with high conductivity and high reflectivity, providing an ideal foundation for the deposition of the antimony layer. By controlling the evaporation rate and temperature, the aluminum layer is ensured to have good uniformity and adhesion. The thickness of the aluminum layer is controlled between 80 and 120 nanometers to ensure its conductivity and mechanical stability.

[0069] Step S5: Evaporation of antimony layer

[0070] After the aluminum layer is evaporated, the antimony layer is evaporated. The substrate with the aluminum layer evaporated is placed in a vacuum evaporation device, and the vacuum degree is maintained at 1x10 -6 Pa. Heat to 200-220°C and perform antimony layer evaporation. Heat the antimony source to 330-350°C and control the evaporation rate of antimony to Until the thickness of the antimony layer reaches 800 to 1000 nanometers.

[0071] The antimony layer is an important component of the photocathode, and its thickness and crystallinity directly affect the cathode's photoelectric conversion efficiency. By strictly controlling the temperature and rate of the evaporation process, the antimony layer is ensured to have excellent crystallinity and uniformity. The baking treatment further improves the crystal structure of the antimony layer, enhancing its adhesion and photoelectric performance.

[0072] The antimony layer evaporation method of the reflective photocathode of the present invention solves the problem that the traditional antimony layer evaporation method only controls the thickness of the antimony layer and the sensitivity of the photocathode is low. Figure 1 As shown, the antimony layer has obvious grains, is flat and uniform; the X-ray diffraction spectrum of the antimony layer is shown in Appendix 2, and the antimony diffraction peak is obvious, which proves that the antimony layer has good crystallinity, which is beneficial to improving the crystallization degree of alkali metal antimonide and ultimately improving the cathode sensitivity.

[0073] The reflective photocathode prepared by the above steps is applied to a photomultiplier tube. Due to the significant improvement of the surface finish of the cathode and the optimization of the antimony layer, the prepared photocathode has higher photoelectric conversion efficiency and sensitivity. The photomultiplier tube prepared by the method of the present invention exhibits higher performance in the fields of spectral analysis, biological detection and radiation detection, and can effectively detect weak light signals and amplify them.

[0074] In order to better understand the present invention, the above method is described in detail below in conjunction with specific embodiments.

[0075] Embodiment 1:

[0076] Step 1: Pre-cleaning

[0077] The nickel substrate was placed in an alkaline cleaning solution with a pH of 12, a cleaning solution temperature of 60°C, and a cleaning time of 10 minutes. The main components of the cleaning solution were sodium hydroxide (NaOH) and deionized water, and the concentration of NaOH was 10%. After cleaning, the substrate was removed from the cleaning solution and rinsed with deionized water three times, each rinse time of 2 minutes, to ensure that all residual alkaline cleaning solution was removed.

[0078] Step 2: Physical polishing

[0079] Use ceramic with a diameter of 2 mm as the polishing medium and fill it to 50% of the polishing tank. Set the rolling speed of the polishing device to 60 rpm and the polishing time to 1 hour. During the polishing process, add the following polishing liquid: 70% deionized water, 15% ethylene glycol, 8% citric acid, 5% triethanolamine, and 0.5% anti-foaming agent. After polishing, rinse the polished substrate 3 times with deionized water to ensure that there is no residue on the surface.

[0080] Step 3: Electrochemical polishing

[0081] The polished substrate is placed in an electrolytic bath, the electrolyte includes 20% of 85% phosphoric acid, 10% of 98% sulfuric acid, 0.5% of sodium chloride, and 0.2% of resist. The voltage is set to 10 volts, the current density is controlled at 20 amperes per square decimeter, the electrochemical polishing temperature is 30°C, and the polishing time is 20 minutes. After polishing, the substrate is immediately rinsed with deionized water to remove the electrolyte residue.

[0082] Step 4: Aluminum layer evaporation

[0083] The polished and cleaned substrate is placed in a vacuum evaporation device, and the vacuum degree of the device is drawn to 1x1010 -6 Pa. The aluminum source is heated to 840°C and the evaporation rate is controlled at Until the thickness of the aluminum layer reaches 100 nanometers. After the evaporation is completed, slowly cool to room temperature and take out the substrate.

[0084] Step 5: Antimony layer evaporation

[0085] Antimony layer was deposited on the aluminum layer, and the vacuum degree was maintained at 1x10 -6 Pa. Heated to 210℃, antimony layer was evaporated. Heated antimony source to 340℃, evaporation rate was Until the thickness of the antimony layer reaches 850 nanometers.

[0086] Embodiment 2:

[0087] Step 1: Pre-cleaning

[0088] The nickel substrate was placed in an alkaline cleaning solution with a pH of 10, a cleaning solution temperature of 55°C, and a cleaning time of 8 minutes. The cleaning solution consisted of potassium hydroxide (KOH) and deionized water, and the concentration of KOH was 8%. After cleaning, the substrate was rinsed 4 times with deionized water, each rinsing time being 1.5 minutes.

[0089] Step 2: Physical polishing

[0090] Use ceramic balls with a diameter of 3 mm as polishing media and fill them to 45% of the polishing tank. Set the rolling speed of the polishing device to 50 rpm and the polishing time to 1.5 hours. The polishing liquid formula is 65% deionized water, 12% ethylene glycol, 10% citric acid, 4% triethanolamine, and 0.3% anti-foaming agent. After polishing, rinse the polished substrate with deionized water.

[0091] Step 3: Electrochemical polishing

[0092] The electrolyte composition is 15% phosphoric acid with a concentration of 85%, 12% sulfuric acid with a concentration of 98%, 0.3% sodium chloride, and 0.1% resist. The voltage is set to 12 volts, the current density is 25 amperes per square decimeter, the electrochemical polishing temperature is controlled at 35°C, and the polishing time is 15 minutes. After polishing, the substrate is rinsed with deionized water and dried.

[0093] Step 4: Aluminum layer evaporation

[0094] Place the substrate in a vacuum evaporation device and adjust the vacuum degree to 1x10 -6 Pa. The aluminum source is heated to 830°C and the evaporation rate is Until the thickness of the aluminum layer reaches 90 nanometers. After the evaporation is completed, slowly cool to room temperature.

[0095] Step 5: Antimony layer evaporation

[0096] The vacuum degree was maintained at 1x10 -6 Pa, heated to 205℃, antimony layer was evaporated. Antimony source was heated to 335℃, and the evaporation rate was Until the thickness of the antimony layer reaches 845 nanometers.

[0097] Embodiment 3:

[0098] Step 1: Pre-cleaning

[0099] An alkaline cleaning solution with a pH of 11 was used, the cleaning solution temperature was 65° C., and the cleaning time was 12 minutes. The cleaning solution composition was 10% sodium hydroxide (NaOH) and deionized water. After cleaning, the substrate was rinsed with deionized water 3 times, each time for 2 minutes.

[0100] Step 2: Physical polishing

[0101] A ceramic with a diameter of 4 mm was used as the polishing medium, filling 55% of the polishing tank. The rolling speed of the polishing device was set to 40 rpm, and the polishing time was 2 hours. The polishing liquid formula was 70% deionized water, 10% ethylene glycol, 6% citric acid, 3% triethanolamine, and 0.2% anti-foaming agent. After polishing, the substrate was thoroughly cleaned with deionized water.

[0102] Step 3: Electrochemical polishing

[0103] The electrolyte includes 25% phosphoric acid at 85% concentration, 8% sulfuric acid at 98% concentration, 0.7% sodium chloride, and 0.3% resist. The voltage is set to 8 volts, the current density is 15 amperes per square decimeter, the electrochemical polishing temperature is 25°C, and the polishing time is 25 minutes. After polishing, the substrate is rinsed with deionized water and dried.

[0104] Step 4: Aluminum layer evaporation

[0105] At a vacuum degree of 1x10 -6 Pa, the aluminum source is heated to 690 ° C, and the evaporation rate is Until the aluminum layer thickness reaches 110 nanometers. After completion, slowly cool to room temperature.

[0106] Step 5: Antimony layer evaporation

[0107] Maintain vacuum at 1x10 -6 Pa, heated to 205℃, antimony layer was evaporated. Antimony source was heated to 645℃, and the evaporation rate was Until the thickness of the antimony layer reaches 155 nanometers.

[0108] Embodiment 4:

[0109] Step 1: Pre-cleaning

[0110] The nickel substrate was placed in an alkaline cleaning solution with a pH of 13, a cleaning solution temperature of 75°C, and a cleaning time of 7 minutes. The cleaning solution consisted of 12% sodium hydroxide (NaOH) and deionized water. After cleaning, the substrate was rinsed with deionized water for 3 times, each time for 1 minute.

[0111] Step 2: Physical polishing

[0112] Ceramic balls with a diameter of 2.5 mm were used as polishing media, filling 60% of the polishing tank. The rolling speed of the polishing device was set to 90 rpm, and the polishing time was 0.5 h. The polishing liquid formula was 72% deionized water, 14% ethylene glycol, 8% citric acid, 5% triethanolamine, and 1% antifoaming agent. After polishing, the substrate was rinsed with deionized water.

[0113] Step 3: Electrochemical polishing

[0114] The electrolyte includes 18% phosphoric acid at 85% concentration, 10% sulfuric acid at 98% concentration, 0.4% sodium chloride, and 0.1% resist. The voltage is set to 14 volts, the current density is 28 amperes per square decimeter, the electrochemical polishing temperature is 38°C, and the polishing time is 12 minutes. After polishing, the substrate is rinsed with deionized water and dried.

[0115] Step 4: Aluminum layer evaporation

[0116] At a vacuum degree of 1x10 -6 Pa, the aluminum source is heated to 820 ° C, and the evaporation rate is Until the thickness of the aluminum layer reaches 115 nanometers. After the evaporation is completed, slowly cool to room temperature.

[0117] Step 5: Antimony layer evaporation

[0118] The vacuum degree was maintained at 1x10 -6Pa, heated to 220℃, antimony layer was evaporated. Antimony source was heated to 650℃, and the evaporation rate was Until the thickness of the antimony layer reaches 860 nanometers.

[0119] Embodiment 5:

[0120] Step 1: Pre-cleaning

[0121] An alkaline cleaning solution with a pH of 9 was used, the cleaning solution temperature was 50° C., and the cleaning time was 15 minutes. The cleaning solution composition was 5% potassium hydroxide (KOH) and deionized water. After cleaning, the substrate was rinsed with deionized water 4 times, each time for 2 minutes.

[0122] Step 2: Physical polishing

[0123] A ceramic with a diameter of 1 mm was used as the polishing medium, filling 45% of the polishing tank. The rolling speed of the polishing device was set to 80 rpm, and the polishing time was 1.5 hours. The polishing liquid formula was 60% deionized water, 18% ethylene glycol, 9% citric acid, 3% triethanolamine, and 0.1% antifoaming agent. After polishing, the substrate was thoroughly rinsed with deionized water.

[0124] Step 3: Electrochemical polishing

[0125] The electrolyte includes 30% phosphoric acid with a concentration of 85%, 5% sulfuric acid with a concentration of 98%, 1% sodium chloride, and 0.05% resist. The voltage is set to 6 volts, the current density is 12 amperes per square decimeter, the electrochemical polishing temperature is 22°C, and the polishing time is 30 minutes. After polishing, the substrate is rinsed with deionized water and dried.

[0126] Step 4: Aluminum layer evaporation

[0127] At a vacuum degree of 1x10 -6 Pa, the aluminum source is heated to 810°C, and the evaporation rate is The thickness of the aluminum layer reached 85 nanometers. After completion, it was slowly cooled to room temperature.

[0128] Step 5: Antimony layer evaporation

[0129] Maintain vacuum at 1x10 -6 Pa, heated to 200℃, antimony layer was evaporated. Antimony source was heated to 330℃, and the evaporation rate was Until the thickness of the antimony layer reaches 940 nanometers.

[0130] Test experiment 1: Sensitivity test

[0131] Objective: To compare the photoelectric conversion efficiency and sensitivity of reflective photocathodes prepared by the processing method of the present invention and the traditional method.

[0132] Experimental setup

[0133] 1. Sample preparation:

[0134] Experimental group: 5 samples of examples prepared using the method of the present invention.

[0135] Control group: samples prepared by traditional processing methods, including ordinary mechanical polishing, no aluminum layer evaporation, and no control of the thickness and temperature of the antimony layer evaporation.

[0136] 2. Light source:

[0137] Use a standard white LED light source with a power of 10mW / cm 2 .

[0138] Each sample was placed under a light source, with the light source 10 cm away from the sample surface.

[0139] 3. Test equipment:

[0140] The photocurrent generated at the cathode was measured using a high-sensitivity digital ammeter.

[0141] Each sample was tested under the same lighting conditions and the resulting current value was recorded.

[0142] Experimental procedures

[0143] 1. Prepare the test sample:

[0144] The experimental and control samples were placed in a clean test environment.

[0145] Make sure the surface of each sample is clean and free of contaminants.

[0146] 2. Lighting test:

[0147] Place the first sample in the test position, turn on the light source, and make sure that the light source evenly illuminates the sample surface.

[0148] Use an ammeter to record the current value generated by the sample under light, measure it five times in a row, and take the average value.

[0149] Repeat the above steps for all experimental and control group samples.

[0150] The results are shown in Table 1:

[0151] Table 1 Photoelectric conversion efficiency test data of photocathode samples

[0152]

[0153]

[0154] According to the experimental data in Table 1, the method of the present invention significantly improves the photoelectric conversion efficiency and sensitivity of the reflective photocathode.

[0155] 1. Analysis of photoelectric conversion efficiency improvement:

[0156] The average current value of the experimental group samples is generally higher than that of the control group samples. For example, the average current of Example 5 in the experimental group is 15.20 μA, while the average current of the control group is 8.40 μA. This indicates that the experimental group samples generate more photocurrent when receiving the same light source.

[0157] This improvement is mainly attributed to the improved substrate processing steps (including fine physical and electrochemical polishing) and the optimized evaporation process of the antimony layer and the aluminum layer in the present invention. These steps significantly improve the uniformity and smoothness of the photocathode surface, reduce surface scattering and absorption, and thus increase the effective capture and conversion of photons.

[0158] 2. Influence of surface treatment:

[0159] Physical polishing (such as the roller polishing in the embodiment using a polishing medium with a diameter of 1-5 mm) effectively removes surface roughness and provides a smoother substrate surface, which helps to uniformly deposit subsequent aluminum and antimony layers, reduces defect points, and thus improves the photoelectric performance of the cathode.

[0160] Electrochemical polishing further improves the surface finish and optimizes the substrate microstructure by precisely controlling the chemistry and current distribution. This not only improves the light reflection properties of the cathode surface, but also enhances the adhesion of the aluminum and antimony layers.

[0161] 3. Optimization of evaporation process:

[0162] In the present invention, the evaporation of the aluminum layer as an intermediate layer improves the reflectivity of the substrate and provides a uniform and conductive platform for the deposition of the antimony layer. The high quality and excellent performance of the aluminum layer are ensured by controlling the evaporation rate and temperature.

[0163] The antimony layer is evaporated on the aluminum layer, and the thickness of the evaporation and the subsequent baking process are strictly controlled to optimize the crystallinity of the antimony layer. Optimized crystallinity is crucial to improve the photoelectric conversion efficiency and sensitivity of the cathode.

[0164] These technological innovations enable the photocathode prepared by the present invention to have a higher response speed and a better signal-to-noise ratio, enabling it to perform well in applications requiring high sensitivity (such as spectral analysis and biological detection).

[0165] Experiment 2: Reflectivity Test

[0166] Purpose: To evaluate and compare the surface reflectivity of reflective photocathodes prepared by the method of the present invention and conventional methods, in order to verify the effectiveness of the present invention in improving cathode reflectivity.

[0167] Experimental setup

[0168] 1. Sample preparation:

[0169] Experimental group: 5 samples of Examples (Example 1 to Example 5) prepared using the method of the present invention.

[0170] Control group: samples prepared by the traditional method. The traditional method does not include the aluminum layer evaporation step, and only uses ordinary polishing and direct evaporation of the antimony layer.

[0171] 2. Light source:

[0172] A standard spectrum visible light source (wavelength 400nm to 700nm) was used to illuminate the sample surface.

[0173] Each sample was tested for reflectivity at the same angle (vertical incidence).

[0174] 3. Test equipment:

[0175] The reflectance of the samples in the range of 400 nm to 700 nm was measured using a spectrophotometer (UV-Vis spectrophotometer).

[0176] The reflectance data of each sample was measured at 5 different wavelengths (450nm, 500nm, 550nm, 600nm, 650nm).

[0177] Experimental procedures

[0178] 1. Prepare the test sample:

[0179] The experimental and control group samples were placed in a dust-free environment to ensure that there was no dust and contaminants on the sample surface.

[0180] 2. Spectral reflectance measurement:

[0181] Place the first sample on the test stage of the spectrophotometer, making sure the light source is shining at a perpendicular angle to the sample.

[0182] Measure and record the reflectance of the sample at 450nm, 500nm, 550nm, 600nm and 650nm.

[0183] Repeat the above steps for all experimental and control group samples.

[0184] The results are shown in Table 2:

[0185] Table 2 Spectral reflectivity test data of photocathode samples

[0186]

[0187]

[0188] According to the reflectivity test data in Table 2, the present invention significantly improves the reflectivity of the reflective photocathode by optimizing the surface treatment and evaporation process of the cathode, especially at the central wavelength of the spectral range (550nm to 600nm).

[0189] 1. The main factors for improving reflectivity:

[0190] Introduction and optimization of aluminum layer: In all experimental group samples, the introduction of aluminum layer as an intermediate layer is one of the key innovations of the present invention. Aluminum is widely used in reflective materials due to its high reflective properties. The present invention ensures the quality and uniformity of the aluminum layer by precisely controlling the thickness of the aluminum layer and the evaporation conditions, thereby significantly enhancing the reflective ability of the substrate.

[0191] 2. Influence of surface treatment:

[0192] Physical and electrochemical polishing: Through physical polishing and electrochemical polishing, the present invention effectively reduces the microscopic defects and unevenness of the substrate surface. The smooth surface reduces the scattering of light and improves the effective reflection of incident light. These polishing steps not only improve the surface quality of the substrate, but also provide an ideal foundation for the uniform deposition of the aluminum layer and the antimony layer.

[0193] 3. Optimization of antimony layer:

[0194] Antimony layer evaporation control: By precisely controlling the evaporation parameters of the antimony layer, the present invention ensures the uniformity and excellent crystallinity of the antimony layer. The optimized antimony layer not only improves the photoelectric efficiency of the cathode, but also enhances its reflective performance, because a more uniform antimony layer helps reduce irregular absorption and scattering on the surface.

[0195] The control group samples, which were not subjected to the aluminum layer evaporation treatment, showed significantly lower reflectivity, which verifies the important role of the aluminum layer in improving the reflectivity and highlights the significant advantages of the present invention in this regard.

[0196] In summary, the present invention significantly improves the reflectivity of the reflective photocathode and thus improves the photoelectric conversion efficiency by introducing aluminum layer evaporation, refined surface pretreatment and optimization of antimony layer evaporation.

[0197] Experiment 3: Sensitivity test

[0198] Purpose: To evaluate and compare the sensitivity of reflective photocathodes prepared by the method of the present invention and traditional methods, so as to verify the effect of the present invention in improving the sensitivity of photoelectric devices.

[0199] Experimental setup

[0200] 1. Sample preparation:

[0201] Experimental group: 5 samples of Examples (Example 1 to Example 5) prepared using the method of the present invention.

[0202] Control group: samples prepared using the traditional method, which does not include the optimized aluminum layer evaporation step and fine surface treatment, but only uses ordinary polishing and antimony layer evaporation.

[0203] 2. Light source:

[0204] A series of low-intensity light sources were used, 1 μW / cm 2 、10μW / cm 2 , 100μW / cm 2 The LED light source illuminates the sample surface.

[0205] Each sample was tested for sensitivity under the same lighting conditions.

[0206] 3. Test equipment:

[0207] The photocurrent generated by each sample at different light intensities was measured using a high-sensitivity digital ammeter.

[0208] Each sample was tested at three light intensities and the generated current value was recorded.

[0209] Experimental procedures

[0210] 1. Prepare the test sample:

[0211] Place the experimental and control samples in a clean, dust-free testing environment.

[0212] 2. Light sensitivity test:

[0213] The first sample was placed in the test position and then 1 μW / cm 2 、10μW / cm 2 , 100μW / cm 2 The light source illuminates the sample.

[0214] The photocurrent generated by the sample at each light intensity was recorded using a digital ammeter.

[0215] Repeat the above steps for all experimental and control group samples.

[0216] The results are shown in Table 3:

[0217] Table 3 Photoelectric sensitivity test data of photocathode samples

[0218]

[0219] According to the data in Table 3, the method of the present invention significantly improves the sensitivity of the reflective photocathode, and especially shows better performance than the traditional method under different light intensity conditions.

[0220] 1. The role of aluminum layer evaporation:

[0221] Enhanced light reflection: The aluminum layer played a key role in the experiment due to its high reflectivity. The introduction of the aluminum layer significantly enhanced the light reflection ability of the substrate, allowing more light energy to be converted into electrons, thereby increasing the photocurrent output. For example, the experimental group samples at 100μW / cm 2 The average photocurrent under high light intensity reached about 90nA, while the control group was only 42.5nA, which is directly attributed to the efficient light reflection performance of the aluminum layer.

[0222] Optimizing evaporation parameters: By precisely controlling the thickness of the aluminum layer and the evaporation conditions, the uniformity and quality of the aluminum layer are ensured, further improving the overall performance of the photocathode.

[0223] 2. Optimization of surface treatment technology:

[0224] Physical and electrochemical polishing: Physical polishing effectively removes surface roughness by using fine polishing media, while subsequent electrochemical polishing further smoothes the surface and reduces surface defects. These treatments not only improve the surface finish, but also optimize the adhesion of the aluminum and antimony layers, providing a good foundation for efficient photoelectric conversion.

[0225] Surface finish and photoelectric effect: Optimization of the surface treatment steps reduces light scattering and absorption, allowing more light energy to be effectively utilized. This is particularly critical for performance under low light intensities, because every small surface improvement can significantly increase the generation of photocurrent.

[0226] 3. Precise control of antimony layer evaporation:

[0227] Antimony layer thickness and evaporation conditions: The present invention optimizes the crystallinity and uniformity of the antimony layer by precisely controlling the thickness of the antimony layer and the evaporation parameters. A more uniform and well-crystallized antimony layer helps to improve the electron emission efficiency and reduce the probability of electron recombination, thereby improving the efficiency of the photoelectric effect.

[0228] The present invention systematically optimizes the cathode preparation process, and carefully designs each step from substrate processing to evaporation layer to ensure the maximum performance of the final product. This comprehensive approach is lacking in traditional technologies, which often focus on improving a single step.

[0229] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for substrate treatment and antimony layer evaporation for improving the sensitivity of a reflective photocathode, characterized in that: The following steps are involved: Pre-cleaning the cathode substrate using an alkaline cleaning solution, wherein the pH value of the alkaline cleaning solution is 9 to 14; Using a polishing device to perform physical polishing on the pre-cleaned cathode substrate; performing electrochemical polishing on the polished cathode substrate; Vapor depositing an aluminum layer on the polished cathode substrate, wherein the thickness of the aluminum layer is 80 to 120 nanometers; The antimony layer is deposited on the aluminum layer, the thickness of the antimony layer is controlled to be 800-1000 nanometers, the baking temperature is 200-220°C, and the evaporation rate is 2. The method for substrate treatment and antimony layer evaporation for improving the sensitivity of a reflective photocathode according to claim 1, characterized in that: The cleaning temperature of the pre-cleaning treatment is 50-80° C., the cleaning time is 5-15 minutes, and after cleaning, the cleaning process also includes rinsing with deionized water to remove residual alkaline cleaning solution.

3. The method for substrate treatment and antimony layer evaporation for improving the sensitivity of a reflective photocathode according to claim 1, characterized in that: The physical polishing step comprises: The barrel polishing process comprises the following steps: Choose ceramic or resin with a diameter of 1 to 5 mm as the polishing medium; Filling the polishing medium into the polishing tank with a filling rate of 40 to 60%; The rolling speed of the polishing device is set to 30 to 100 rpm and the polishing time is 0.5 to 2 hours; During the polishing process, a polishing solution is added, wherein the polishing solution comprises deionized water, ethylene glycol, citric acid, triethanolamine and an anti-foaming agent; After polishing is completed, the polished cathode substrate is rinsed with deionized water.

4. The method for substrate treatment and antimony layer evaporation for improving the sensitivity of a reflective photocathode according to claim 3, characterized in that: The polishing liquid comprises the following components by volume percentage: Deionized water: 60-75%; Ethylene glycol: 10-20%; Citric acid: 5-10%; Triethanolamine: 2-5%; Antifoaming agent: 0.1~1%.

5. The method for substrate treatment and antimony layer evaporation for improving the sensitivity of a reflective photocathode according to claim 1, characterized in that: The electrochemical polishing treatment step comprises: placing the cathode substrate in an electrolytic cell containing an electrolyte comprising phosphoric acid and sulfuric acid; Applying a voltage of 5 to 15 volts and controlling a current density of 10 to 30 amperes per square decimeter; The electrochemical polishing treatment is continued for 5 to 30 minutes at a temperature of 20 to 40°C; After polishing, the cathode substrate was immediately removed from the electrolytic cell and rinsed with deionized water to remove residual electrolyte.

6. The method for substrate treatment and antimony layer evaporation for improving the sensitivity of a reflective photocathode according to claim 5, characterized in that: The electrolyte comprises the following components by volume percentage: 85% phosphoric acid: 10-30%; 98% sulfuric acid: 5-15%; Sodium chloride: 0.1-1%; Anti-corrosion agent: 0.05~0.5%.

7. The method for substrate treatment and antimony layer evaporation for improving the sensitivity of a reflective photocathode according to claim 1, characterized in that: The method further comprises cleaning the polished parts after the electrochemical polishing treatment, wherein the cleaning treatment comprises rinsing the parts with deionized water or ultrapure water at a temperature of room temperature to 40° C., drying the parts at a temperature of 50 to 70° C. for 10 to 30 minutes after rinsing, and then performing a vacuum degassing treatment at 550° C. with a vacuum degree of 1×10 -5 Pa, and lasts for 1 to 3 hours.

8. The method for substrate treatment and antimony layer evaporation for improving the sensitivity of a reflective photocathode according to claim 1, characterized in that: The step of evaporating an aluminum layer on the polished cathode substrate comprises: Place the cathode substrate after vacuum degassing in a vacuum evaporation device and draw the vacuum degree of the device to 1x10 -6 Pa; Heating the aluminum source to its evaporation temperature, the temperature range is 810 ~ 850 ° C; The aluminum evaporation rate is controlled to Perform evaporation until the thickness of the aluminum layer reaches a set value; After the evaporation is completed, slowly cool to room temperature.

9. The method for substrate treatment and antimony layer evaporation for improving the sensitivity of a reflective photocathode according to claim 1, characterized in that: The step of evaporating an antimony layer on the aluminum layer comprises: The cathode substrate with the aluminum layer deposited on it is placed in a vacuum deposition device, and the vacuum degree of the device is drawn to 1x10 -6 Pa; Heating to 200-220°C, performing antimony layer evaporation; Heat the antimony source to its evaporation temperature, which ranges from 330 to 350°C; The evaporation rate of antimony is controlled until the thickness of the antimony layer reaches a set value.

10. A photomultiplier tube, characterized in that: It comprises a reflective photocathode prepared according to the method according to any one of claims 1-9.

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