Large grain Cu(In,Ga)Se2 thin film growth using a Se-radical beam source

Cu(In,Ga)Se2 (CIGS) thin films were grown by the three-stage process using a rf-plasma cracked Se-radical beam source. CuGaSe2 (CGS) films grown at a maximum substrate temperature of 550 °C and CuInSe2 (CIS) and CIGS films grown at the lower temperature of 400 °C exhibited highly dense surfaces and large grain size compared with films grown using a conventional Se-evaporative source. This result is attributed to the modification of the growth kinetics due to the presence of active Se-radical species and enhanced surface migration during growth. The effect on CIGS film properties and solar cell performance has been investigated. Enhancements in the cell efficiencies of 400 °C-grown CIS and CIGS solar cells have been demonstrated using a Se-radical source.