Optoelectronic devices including heterojunction and intermediate layer

An optoelectronic semiconductor device comprising:nan absorber layer made of gallium arsenide (GaAs) and having only one type of doping;an emitter layer located closer than the absorber layer to a back side of the device, the emitter layer made of a different material than the absorber layer and having a higher bandgap than the absorber layer;a heterojunction formed between the emitter layer and the absorber layer;a p-n junction formed between the emitter layer and the absorber layer at a location offset from the heterojunction, the p-n junction causing a voltage to be generated in the device in response to the device being exposed to light at a front side of the device; andan intermediate layer located between the absorber layer and the emitter layer and providing the offset of the p-n junction from the heterojunction, the intermediate layer having the same type of doping as the absorber layer and including the different material,wherein the intermediate layer includes:na graded layer having a material gradation from GaAs at a side closer to the absorber layer, to the different material of the emitter layer, anda back window layer not having the gradation and having an approximately uniform composition of the different material.

A solar cell comprising:nan absorber layer made of gallium arsenide (GaAs) and having only one type of doping;an emitter layer made of a different material than the absorber layer and having a higher bandgap than the absorber layer;an intermediate layer provided between the absorber layer and the emitter layer, the intermediate layer having the same type of doping as the absorber layer, wherein the intermediate layer includes a material gradation from GaAs at a side closer to the absorber layer, to the different material of the emitter layer at a side closer to the emitter layer, wherein the intermediate layer includes:n(a) a graded layer having the gradation, and(b) a back window layer not having the gradation and having an approximately uniform composition of the different material;a heterojunction formed between the emitter layer and the absorber layer; anda p-n junction formed between the emitter layer and the absorber layer and at least partially within the different material at a location offset from the heterojunction, the p-n junction causing a voltage to be generated in the cell in response to the cell being exposed to light at a front side of the cell.