Semiconductor photoelectron emission device

A semiconductor photoelectron emission device comprising:

• ohmic contacts;
• a first layer of p-type Al.sub.x Ga.sub.(1-x) Sb, wherein x is a positive number less than 1, having high impurity concentration and predetermined forbidden band and being of an indirect transition type semiconductor;
• a second layer of Al.sub.x Ga.sub.(1-x) Sb having a low impurity concentration and wider forbidden band;
• a third layer of n-type GaSb, said third layer having at selected portions, different layers of direct transition type semiconductor of p-type impurity thereby to form thereat with said first layer a heterojunction;
• said third layer and said first layer having substantially the same crystal structures at said junction and having small differences in lattic constants;
• a fourth layer at parts of said third layer substantially absent said diffused p-type impurity, said fourth layer comprising high concentration p-type Al.sub.x Ga.sub.(1-x) Sb;
• a fifth layer of p-type GaSb on said fourth layer;
• and electrodes on said fifth layer, whereby said ohmic contacts are disposed on said first layer at selected areas wherein transversely are absent said diffused p-type impurities, and said first layer has an electron emissive surface at areas not covered by said ohmic contacts and thereby to form a transmission type device.