give the desired p layer composition the deposition occurs at a pressure of about 0 1 1 0 torr and at a temperature of about 150 u00b0 300 u00b0 c deposition is continued for a sufficient period of time to deposit a layer of the desired thickness a p layer having a band gap between bout 1 9 and 2 0 ev a dark conductivity of about 10 6 reciprocal ohm centimeters and a light conductivity of about 10 5 reciprocal ohm centimeters can be obtained in this manner after the p layer is deposited the glow discharge chamber is purged to avoid any contamination of the i layer which is deposited next deposition of the i layer is then accomplished by evacuating the chamber and back filling with pure silane gas deposition then proceeds at a pressure of about 0 1 1 0 torr and a temperature of about 150 u00b0 300 u00b0 c following deposition of the i layer the chamber is pumped down and back filled for deposition of the n layer in order to deposit the desired silicon and phosphorous composition comprising the n layer silane and a mixture of phosphine in an inert gas are passed through.