Effects of deposition termination on Cu2ZnSnSe4 device characteristics

Co-evaporated Cu2ZnSnSe4 (CZTSe) is used to examine sensitivities to the device performance that originate from variations in Zn content very near the surface. While integral Zn content of the film is held approximately constant, the surface composition is manipulated via changes to the Zn flux at the end of the deposition. Surface composition, device performance, and open-circuit voltage extrapolated to zero temperature are measured as a function of deposition termination. Origins of the apparent reduction in surface recombination with increasing Zn are discussed.