Optoelectronic devices including heterojunction and intermediate layer

摘要

Embodiments generally relate to optoelectronic semiconductor devices such as solar cells. In one aspect, a device includes an absorber layer made of gallium arsenide (GaAs) and having only one type of doping. An emitter layer is located closer than the absorber layer to a back side of the device and is made of a different material and having a higher bandgap than the absorber layer. A heterojunction is formed between the emitter layer and the absorber layer, and a p-n junction is formed between the emitter layer and the absorber layer and at least partially within the different material at a location offset from the heterojunction. An intermediate layer is located between the absorber layer and the emitter layer and provides the offset of the p-n junction from the heterojunction, and includes a graded layer and an ungraded back window layer.

主权项

1. An optoelectronic semiconductor device comprising:
an 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; and an 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:
a 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.