Growth of InN and InGaN on Si substrate for solar cell applications

Epitaxial growth of InN and InGaN films by radio-frequency plasma-excited molecular beam epitaxy was studied as a key technology for the realization of a new high-efficiency tandem solar cell. Much improvement of InN and InGaN films on Si, which is necessary for the realization of a high-efficiency solar cell, was realized by brief substrate nitridation for 3 min prior to growth by MBE. Photoluminescence peaks at less than 0.8 eV were observed for all samples independent of the crystallinity of InN, which supports the recent reports of band-gap energy of InN being 0.7-0.8 eV. Rectifying characteristics and photovoltaic characteristics were also observed in our n-InN/p-Si heterojunctions.