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Title: An electron impact emission spectroscopy flux sensor for monitoring deposition rate at high background gas pressure with improved accuracy

Abstract

Electron impact emission spectroscopy (EIES) has been proven to be a critical tool for film composition control during codeposition processes for the fabrication of multicomponent thin film materials including the high-efficiency copper-indium-gallium-diselenide photovoltaic cells. This technique is highly specific to atomic species because the emission spectrum of each element is unique, and the typical width of atomic emission lines is very narrow. Noninterfering emission lines can generally be allocated to different atomic species. However, the electron impact emission spectra of many molecular species are often broadband in nature. When the optical emission from an EIES sensor is measured by using a wavelength selection device with a modest resolution, such as an optical filter or monochromator, the emissions from common residual gases may interfere with that from the vapor flux and cause erroneous flux measurement. The interference is most pronounced when measuring low flux density with the presence of gases such as in reactive deposition processes. This problem is solved by using a novel EIES sensor that has two electron impact excitation sources in separate compartments but with one common port for optical output. The vapor flux is allowed to pass through one compartment only. Using a tristate excitation scheme andmore » appropriate signal processing technique, the interfering signals from residual gases can be completely eliminated from the output signal of the EIES monitor for process control. Data obtained from Cu and Ga evaporations with the presence of common residual gases such as CO{sub 2} and H{sub 2}O are shown to demonstrate the improvement in sensor performance. The new EIES sensor is capable of eliminating the effect of interfering residual gases with pressure as high as in the upper 10{sup -5} Torr range.« less

Authors:
; ;  [1];  [2]
  1. C. Lu Laboratory, 1012A Linda Vista Avenue, Mountain View, California 94043 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
21192402
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films; Journal Volume: 26; Journal Issue: 4; Conference: 54. international AVS symposium, Seattle, WA (United States), 14-19 Oct 2007; Other Information: DOI: 10.1116/1.2830633; (c) 2008 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CARBON DIOXIDE; CATHODOLUMINESCENCE; COPPER; DEPOSITION; ELECTRONS; EMISSION SPECTRA; EMISSION SPECTROSCOPY; EXCITATION; FLUX DENSITY; GALLIUM; INDIUM; OPTICAL FILTERS; PHOTOVOLTAIC CELLS; PROCESS CONTROL; SENSORS; SIGNALS; THIN FILMS; VAPORS; X-RAY PHOTOELECTRON SPECTROSCOPY

Citation Formats

Lu, C., Blissett, C. D., Diehl, G., and Sigma Instruments, 120 Commerce Drive Unit 1, Fort Collins, Colorado 80524. An electron impact emission spectroscopy flux sensor for monitoring deposition rate at high background gas pressure with improved accuracy. United States: N. p., 2008. Web. doi:10.1116/1.2830633.
Lu, C., Blissett, C. D., Diehl, G., & Sigma Instruments, 120 Commerce Drive Unit 1, Fort Collins, Colorado 80524. An electron impact emission spectroscopy flux sensor for monitoring deposition rate at high background gas pressure with improved accuracy. United States. doi:10.1116/1.2830633.
Lu, C., Blissett, C. D., Diehl, G., and Sigma Instruments, 120 Commerce Drive Unit 1, Fort Collins, Colorado 80524. Tue . "An electron impact emission spectroscopy flux sensor for monitoring deposition rate at high background gas pressure with improved accuracy". United States. doi:10.1116/1.2830633.
@article{osti_21192402,
title = {An electron impact emission spectroscopy flux sensor for monitoring deposition rate at high background gas pressure with improved accuracy},
author = {Lu, C. and Blissett, C. D. and Diehl, G. and Sigma Instruments, 120 Commerce Drive Unit 1, Fort Collins, Colorado 80524},
abstractNote = {Electron impact emission spectroscopy (EIES) has been proven to be a critical tool for film composition control during codeposition processes for the fabrication of multicomponent thin film materials including the high-efficiency copper-indium-gallium-diselenide photovoltaic cells. This technique is highly specific to atomic species because the emission spectrum of each element is unique, and the typical width of atomic emission lines is very narrow. Noninterfering emission lines can generally be allocated to different atomic species. However, the electron impact emission spectra of many molecular species are often broadband in nature. When the optical emission from an EIES sensor is measured by using a wavelength selection device with a modest resolution, such as an optical filter or monochromator, the emissions from common residual gases may interfere with that from the vapor flux and cause erroneous flux measurement. The interference is most pronounced when measuring low flux density with the presence of gases such as in reactive deposition processes. This problem is solved by using a novel EIES sensor that has two electron impact excitation sources in separate compartments but with one common port for optical output. The vapor flux is allowed to pass through one compartment only. Using a tristate excitation scheme and appropriate signal processing technique, the interfering signals from residual gases can be completely eliminated from the output signal of the EIES monitor for process control. Data obtained from Cu and Ga evaporations with the presence of common residual gases such as CO{sub 2} and H{sub 2}O are shown to demonstrate the improvement in sensor performance. The new EIES sensor is capable of eliminating the effect of interfering residual gases with pressure as high as in the upper 10{sup -5} Torr range.},
doi = {10.1116/1.2830633},
journal = {Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films},
number = 4,
volume = 26,
place = {United States},
year = {Tue Jul 15 00:00:00 EDT 2008},
month = {Tue Jul 15 00:00:00 EDT 2008}
}