AMORPHOUS silicon grown by the rf glow discharge decomposition of silane in the process developed by Spear and Le Comber1,2 is one of the most promising materials found so far in the search for a cheap, large-area solar cell. Only two results, albeit encouraging, have been reported by RCA for p-n cells3 (AMI efficiency 2.4%) and anti-reflection coated platinum Schottky barrier cells4 (AMI efficiency 5.5%), but with area only =2×10-2 cm2. We report here the achievement of comparable efficiencies for a Schottky barrier cell, incorporating an insulating layer between the metal and semiconductor (an M-I-S cell) and with significantly greater area. The insulating layer is tailored to compensate for the low work function of the cheaper barrier metal (nickel) which we have used5-9, leading to higher cell voltages otherwise obtainable only with higher work function metals. This is a significant step forward in the development of large area terrestrial solar cells. © 1978 Nature Publishing Group.