The effect of O/sub 2/ on H/sub 2/Se selenization in a continuous flow reactor

Cu-In bilayers were reacted to form CuInSe/sub 2/ in a continuous flow tubular reactor using a dilute H/sub 2/Se mixture. The system was evacuated to 1/spl times/10/sup -6/ torr prior to the introduction of the reacting gas to remove all gas phase contaminants. High efficiency solar cells could not be made on CuInSe/sub 2/ films formed using only H/sub 2/Se as the reacting gas. However, by mixing O/sub 2/ with the H/sub 2/Se, CuInSe/sub 2/ was formed and cells with efficiencies over 10% were fabricated. The O/sub 2/ reacts with the H/sub 2/Se in the gas phase forming Se/sub x/ species. At O/sub 2H/sub 2/Se ratios of 0.9 to 0.2, Cu/sub 7/Se/sub 4/ and In/sub 2/O/sub 3/ along with CuInSe/sub 2/ are formed. At low O/sub 2H/sub 2/Se ratios, 0.02 to 0.004, single phase CuInSe/sub 2/ films are formed which are suitable for devices.<>