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Activation method for improving stability of gallium arsenide photocathode

A photocathode and stability technology, which is applied in the manufacture of light-emitting cathodes, can solve the unsatisfactory stability of GaAs photocathode and other problems, and achieve the effect of good activation method, easy promotion, and few operation steps

Active Publication Date: 2017-10-03
NANJING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] However, the stability of the GaAs photocathode obtained by these two activation methods is not satisfactory, and we urgently need an activation method that can improve the stability of the photocathode

Method used

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  • Activation method for improving stability of gallium arsenide photocathode
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  • Activation method for improving stability of gallium arsenide photocathode

Examples

Experimental program
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Effect test

Embodiment 1

[0032] The activation process is as follows figure 1 shown.

[0033] Before cesium oxygen activation, we chemically clean and high-temperature purify the GaAs photocathode material.

[0034] The step of chemical cleaning is to first use H with a ratio of 4:1:100 2 SO 4 :H 2 o 2 :H 2 O mixed solution was chemically etched for 1 minute, and then put into HCl:H with a ratio of 1:1 2 O mixed solution was etched for 2 minutes, and finally the sample was repeatedly rinsed with deionized water and dried.

[0035] The step of high temperature purification is to send the sample to a vacuum degree not lower than 10 -7 In the ultra-high vacuum system of the order of Pa, the heating temperature is 650°C and the heating time is 20 minutes. After the sample is naturally cooled to room temperature, the sample is sent to the activation position, and the cesium oxygen activation starts.

[0036] When activated, a tungsten-halogen lamp is used to irradiate the cathode surface verticall...

Embodiment 2

[0043] An activation method for improving the stability of gallium arsenide photocathode, comprising cesium source activation and oxygen source activation, the specific steps are as follows:

[0044] Step 1. Perform chemical cleaning and high-temperature purification on the sample to be activated;

[0045] The chemical cleaning method is as follows: first use H with a ratio of 4:1:100 2 SO 4 :H 2 o 2 :H 2 O mixed solution for chemical etching; then put in HCl:H with a ratio of 1:1 2 O mixed solution was etched, and finally the sample was rinsed with deionized water for at least one minute.

[0046] The high-temperature purification step is: put the sample after chemical cleaning into the ultra-high vacuum system for 30 minutes of heating, the heating temperature is 550°C, and the vacuum degree of the ultra-high vacuum system is not lower than 10 -7 Pa order of magnitude.

[0047] Step 2. Turn on the cesium source, the photocurrent gradually increases, and the photocurre...

Embodiment 3

[0054] An activation method for improving the stability of gallium arsenide photocathode, comprising cesium source activation and oxygen source activation, the specific steps are as follows:

[0055] Step 1. Perform chemical cleaning and high-temperature purification on the sample to be activated;

[0056] The chemical cleaning method is as follows: first use H with a ratio of 4:1:100 2 SO 4 :H 2 o 2 :H 2 O mixed solution for chemical etching; then put in HCl:H with a ratio of 1:1 2 O mixed solution was etched, and finally the sample was rinsed with deionized water for at least one minute.

[0057] The high-temperature purification step is: put the sample after chemical cleaning into the ultra-high vacuum system for 10 minutes of heating, the heating temperature is 650°C, and the vacuum degree of the ultra-high vacuum system is not lower than 10 -7 Pa order of magnitude.

[0058] Step 2. Turn on the cesium source, the photocurrent gradually increases, and the photocurre...

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Abstract

The invention discloses an activation method for improving the stability of a gallium arsenide photocathode. The method comprises cesium source activation and oxygen source activation. The activation method comprises the steps that 1 a cesium source is turned on, the photocurrent gradually increases and the photocurrent reaches the peak and then decreases; 2 when the photocurrent decrease rate is less than 0.2 micron A / min, an oxygen source is turned on, and the cesium source is still turned on and the photocurrent turns to rise; 3 when the photocurrent reaches the peak again, the oxygen source is turned off, and the photocurrent first rises slightly and then immediately decreases; and 4 the steps 2 and 3 are repeated until the photocurrent peak current is no longer increase, and the oxygen source and cesium source are turned off in order to end the activation process. The method provided by the invention can acquire the gallium arsenide photocathode with better stability and higher quantum efficiency, has simple operation steps, and is a better method to realize computer automatic control activation.

Description

technical field [0001] The invention relates to an activation method for preparing a negative electron affinity semiconductor photoelectric emission material, in particular to an activation method for improving the stability of a gallium arsenide photocathode. Background technique [0002] Gallium arsenide (GaAs) photocathode is the core component of modern low-light night vision devices, which can convert weak light signals into electrical signals. important applications. In current photocathode applications, it is required to prepare a photocathode with as high a quantum efficiency as possible and good stability. However, the attenuation of the cathode quantum efficiency over time (that is, cathode stability) is still a problem in the practical process. technical challenge. In an ultra-high vacuum environment, a negative electron affinity (NEA) photocathode is prepared by alternately covering the surface of a clean GaAs material with cesium and oxygen. The activation of ...

Claims

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Application Information

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IPC IPC(8): H01J9/12
CPCH01J9/12
Inventor 张益军汤狸明刘欣欣冯琤钱芸生张俊举张翔
Owner NANJING UNIV OF SCI & TECH
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