Journal of Vacuum Science & Technology A, Vol.17, No.1, 291-296, 1999
Direct observation of Na and O impurities at grain surfaces of CuInSe2 thin films
The authors use field-emission Auger electron spectroscopy to investigate the spatial nature of trace Na and O impurities in thin films of photovoltaic-grade CuInSe2 thin films. They give the first direct proof that Na and O reside at grain surfaces and not in the grain interiors of CuInSe2 (CIS) thin films, and discuss the improvement in photovoltaic conversion efficiency of CIS with Na.