Methods for forming optoelectronic devices including heterojunction

A method for forming a solar cell, the method comprising:

• forming an absorber layer made of gallium arsenide (GaAs) and having only one type of doping;
• forming an emitter layer made of a different material than the absorber layer and having a higher bandgap than the absorber layer;
• and
• forming an intermediate layer 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 a heterojunction is formed between the emitter layer and the absorber layer, and wherein 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, 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.

A method for forming a photovoltaic cell, the method comprising:

• forming an absorber layer made of gallium arsenide (GaAs) and having only one type of doping;
• forming an emitter layer made of a different material than the absorber layer and having a higher bandgap than the absorber layer;
• forming an intermediate layer between the absorber layer and the emitter layer, the intermediate layer having the same type of doping as the absorber layer;
• and
• such that a heterojunction is formed between the emitter layer and the absorber layer and a 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, wherein a majority of the absorber layer is outside of a depletion region formed by the p-n junction, 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.