Characteristics of indium phosphide solar cells bonded on silicon

Indium phosphide solar cells were bonded on silicon substrates by applying a eutectic bonding method. The InP solar cell structure was first grown homoepitaxially on an InP substrate. Gold layers were deposited on top of the InP cell structure and on the Si substrate. These two samples were then put in contact with each other and the structure was heated to 400-500°C so that eutectic alloys formed between Au and the semiconductor materials. When cooling the structure, these two samples stuck together. The InP substrate was then removed by selective etching. After the bonding process the solar cell devices were processed by using the standard photolithographic methods. These cells exhibited low leakage currents, quantum efficiencies almost identical to homoepitaxial InP solar cells and conversion efficiencies of 12.9% under AMO illumination and 16.5% under AM1.5 illumination, which are relatively high in comparison to heteroepitaxial InP solar cells