An Investigation into the relationship of Selenium and Arsenic in Cadmium Telluride Thin Films using STEM-EDX, NanoSIMS and Cathodoluminescence

Ali Abbas1, Kieran Curson1, Stuart Robertson1, Geoff West2, Ian Franchi3, Xuchao Zhao3, Gang Xiong4, Dingyuan Lu4, Mike Walls1 1Loughborough University, Loughborough, --, United Kingdom /2Warwick University, Coventry, --, United Kingdom /3Open University, Milton Keynes, --, United Kingdom /4First Solar, San Francisco , CA, United States

Cadmium Selenium Telluride thin films were deposited with a highly doped arsenic film, which after an cadmium chloride anneal showed an anti-correlation between Selenium and arsenic. This was observed using NanoSIMS on a cleaved surface, as well as cross sectional STEM analysis. Both Selenium and arsenic show preferential grain boundary migration. Arsenic is shown to form a barrier prohibiting the movement of Selenium during recrystallisation of the grains, the reverse is also true.