NDLI: The optimization of (Cs,O) activation of NEA photocathode

Content Provider	IEEE Xplore Digital Library
Author	Du Xiao-qing Chang Ben-kang Du Yu-jie Li Min
Copyright Year	2004
Description	Author affiliation: EE&OE Inst., Nanjing Univ. of Sci. & Technol., China (Du Xiao-qing; Chang Ben-kang; Du Yu-jie; Li Min)
Abstract	As one of the main direction of developing negative electron affinity (NEA) photocathode with higher response performance, the research work on (Cs,O) activation technique of NEA photocathode has been carried. At present the main adoptive activation technique is the "high-low temperature" two-step activation. Although NEA photocathode with high sensitivity has been already prepared by use of this activation method, the research work of activation technique is still semi-experienced and semi-quantitative and therefore the lack of the theoretic guidance of further optimization of activation technique is existent. It is owing to the lack of effective on-line measurement means, and there is not enough useful information obtained during activation. As a result clear and, reasonable explanations for mechanism of activation technique and the details of NEA formation during activation have been inadequate. In this paper, the on-line measurement technology of spectral response and photocurrent are firstly used to research on the "high-low temperature" two-step (Cs,O) activation process of NEA photocathode. A series of GaAs slices were activated and different activation manners were adopted by changing Cs and O exposure coverage in activation cycles. On-line spectral response curves and the dependent curves of photocurrent with (Cs,O) activation cycles were measured during each different activation process, and the variations of photoemission performance parameters of photocathodes, which include threshold wavelength, peak response, peak wavelength, sensitivity and surface escape probability with (Cs,O) deposition cycles were calculated according to the measured curves. By analysis of the relations between different "high-low temperature" activation technique and sensitivity and stability of NEA photocathode, the optimized (Cs,O) activation technique was obtained and the relations between "high temperature" activation and "low temperature" activation was also discovered in this paper. In view of the interaction of GaAs surface and (Cs,O) overlaying atoms and the surface analysis results of GaAs(Cs,O) surface, the formation of NEA surface during activation and mechanisms "high-low temperature" activation were further explored. It was concluded that the surface of NEA photocathode is composed of GaAs-O interface barrier and Cs-O layer, and the purpose of optimization of activation technique is to make an optimized GaAs-O interface barrier with enough small layer thickness and uniform distribution of GaAs-O bonding, and to make an optimized Cs-O layer with sufficient numbers of Cs-O dipoles at a thinner Cs-O layer. The reasons why higher sensitivity can be achieved by "low-temperature" activation compared to "high-temperature" activation are that optimized GaAs-O interface barrier is obtained by low-temperature heat cleaning and the optimized Cs-O layer is also sequentially obtained at the existence of GaAs-O barrier.
File Size	71363
File Format	PDF
ISBN	0780384377
DOI	10.1109/IVESC.2004.1414231
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2004-09-06
Publisher Place	China
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	Temperature sensors Surface waves Wavelength measurement Gallium arsenide Optimization methods Probability Photoelectricity Photoconductivity Cathodes Electrons
Content Type	Text
Resource Type	Article

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Library of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in