Patent ID: 7202102

Claim:
A method of generating an electrical current in response to light comprising the steps of: (a) absorbing light by a light-absorption intrinsic semiconductor layer having a thickness ti, a doping concentration below 5e14 cm −3 , and producing, in response to light absorbed by said light-absorption intrinsic semiconductor layer, electrical carriers that are transported therethrough; (b) absorbing light by a first light absorption doped semiconductor layer doped with one of p- and n-conductivity type-determining impurities, having a thickness td1, and a first doping concentration dc 1 between 1e17 and 2e18 cm −3 , said first light absorption doped semiconductor layer having a first surface thereof abutting a first surface of said light absorption intrinsic semiconductor layer, and producing, in response to light absorbed by said first light absorption doped semiconductor layer, electrical carriers that are transported therethrough, and wherein td1/ti is greater than or equal to 0.17; and (c) extracting electrical current comprised of said carriers produced by and transported through said light-absorption intrinsic semiconductor layer and said first light absorption doped semiconductor layer, by means of a first electrode electrically coupled to said first light absorption doped semiconductor layer, and a second electrode electrically coupled to said light absorption intrinsic semiconductor layer, wherein step (b) further comprises absorbing light by a second light absorption doped semiconductor layer doped with the other of said p- and n-conductivity type-determining impurities, having a thickness td2, and a second doping concentration dc 2 between 1e17 and 2e18 cm −3 , said second light absorption doped semiconductor layer having a first surface thereof abutting a second surface of said light absorption intrinsic semiconductor layer that is spaced apart from said first surface of said light absorption intrinsic semiconductor layer by material of said light absorption intrinsic semiconductor layer therebetween, and producing, in response to light absorbed by said second light absorption doped semiconductor layer, electrical carriers that are transported therethrough, and wherein (td1+td2)/ti is greater than or equal to 0.17, and step (c) comprises extracting said electrical current, comprised of said carriers produced by and transported through said light-absorption intrinsic semiconductor layer and said first and second light absorption doped semiconductor layers, by means of said first electrode electrically coupled to said first light absorption doped semiconductor layer, and said second electrode electrically coupled to said second light absorption doped semiconductor layer.