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Research Of Gaas Substrate Adsorption Stripping

Posted on:2014-01-30Degree:MasterType:Thesis
Country:ChinaCandidate:Z H GeFull Text:PDF
GTID:2248330395983021Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
In the year of1965, GaAs-Cs appears as a new kind of photocathode in the photoemission field. GaAs-Cs owns novel theoretical model. With excellent performance, such as:high sensitivity, low dark current, concentrated electron emission energy and high quantum efficiency, this new kind of photocathode cause profound changes in the photoemission field. Ever since, negative electron affinity (NEA) photocathode manufactured by III-V semiconductor(GaAs, GaN, InP and so on),is widely studied.In the preparation of NEA photocathode, activation process is an important step. The bulk characteristics of the photocathode are determined by the epitaxial growth method of the substrate while the surface properties of the photocathode are decided by the activation process. Before the activation process, the substrate should be atomically clear. Clearing process contain chemical cleaning and high temperature heating cleaning. The chemical cleaning can remove the oil and a part of oxides on the surface, while high temperature heating cleaning can remove the carbides and oxides. The earliest activation process is alternate cover of Cs and O on the GaAs substrate, which can lower the surface potential barrier and produce NEA surface. Ever since, the activation process is improved continuously, the improve methods are focused on the alternate cover way.In this article, to improve the activation process and the integral sensitivity of the NEA photocathode, the adsorption and desorption of foreign gases in the ultra-high vacuum activation system, desorption of oxidation layer during the high temperature heating cleaning process and the adsorption and desorption of Cs and O in the activation process are studied and analyzed. A reasonable activation process is given...
Keywords/Search Tags:NEA photocathode, ultra-high vacuum, activation, adsorption and desorption
PDF Full Text Request
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