DocumentCode :
41434
Title :
Real-Time, In-Line, and Mapping Spectroscopic Ellipsometry for Applications in Cu(In _{{\\bf 1}-{bm x}} Ga </div
Author :
Aryal, Puruswottam ; Pradhan, Parth ; Attygalle, Dinesh ; Ibdah, Abdel-Rahman A. ; Aryal, Krishna ; Ranjan, Viresh ; Marsillac, Sylvain ; Podraza, Nikolas J. ; Collins, Robert W.
Author_Institution :
Dept. of Phys. & Astron., Univ. of Toledo, Toledo, OH, USA
Volume :
4
Issue :
1
fYear :
2014
fDate :
Jan. 2014
Firstpage :
333
Lastpage :
339
Abstract :
In the scale-up of Cu(In1-xGax)Se2 (CIGS) solar cell processing for large-area photovoltaics technology, the challenge is to achieve optimum values of layer thicknesses, as well as CIGS Cu stoichiometry and alloy composition x within narrow ranges and simultaneously over large areas. As a result, contactless metrologies - those that provide such information in real-time or in-line process step by step, with the capabilities of large-area mapping - are of great interest in this technology. We have demonstrated high-speed multichannel spectroscopic ellipsometry (SE) in a number of modes for CIGS metrology, including 1) single-spot real-time SE monitoring of (In1-xGax)2Se3 as the first stage in multisource evaporation of three-stage CIGS; 2) control of Cu stoichiometry in the second and third stages of the process; 3) single-spot in situ SE analysis of alloy composition and grain size averaged through the thickness for the final CIGS film; 4) offline mapping of the CIGS thickness and composition over large areas, as well as mapping after each device fabrication step for correlation with local small area cell performance; 5) ex situ single-spot analysis of alloy composition profiles in CIGS and of completed solar cell stacks to extract thicknesses and properties of semiconductor and contact layers; and 6) predictive capability for quantum efficiency based on the results of SE multilayer analysis. With the future development of new instrumentation, the offline and ex situ capabilities in multilayer analysis and mapping will be possible in-line for both rigid and roll-to-roll flexible substrates.
Keywords :
copper compounds; ellipsometry; gallium compounds; grain size; indium compounds; semiconductor thin films; solar cells; stoichiometry; ternary semiconductors; thickness measurement; CIGS Cu stoichiometry; CIGS layer thicknesses; Cu(In1-xGax)Se2; alloy composition; contact layer thickness; contactless metrologies; ex situ single-spot analysis; grain size; high-speed multichannel spectroscopic ellipsometry; in-line mapping spectroscopic ellipsometry; large-area photovoltaics technology; multilayer analysis; offline mapping; quantum efficiency; real-time mapping spectroscopic ellipsometry; rigid substrates; roll-to-roll flexible substrates; semiconductor layer thickness; single-spot in situ spectroscopic ellipsometry analysis; single-spot real-time spectroscopic ellipsometry monitoring; solar cell processing; Dielectrics; Ellipsometry; Photovoltaic cells; Real-time systems; Rough surfaces; Substrates; Surface roughness; Ellipsometry; gallium-based semiconductor materials; photovoltaic (PV) cells; thickness measurement;
fLanguage :
English
Journal_Title :
Photovoltaics, IEEE Journal of
Publisher :
ieee
ISSN :
2156-3381
Type :
jour
DOI :
10.1109/JPHOTOV.2013.2282745
Filename :
6623109
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