Crystal Growth and Interface Engineering of Group-IV Semiconductor Materials for Multi-Junction Solar Cells(<Special Issue>Novel Solar Cells Utilizing Nano- and Hetero-Structure)

Abstract

We have examined the crystal growth of pseudomorphic epitaxial layers of Ge_<1-x-y>Si_xSn_y ternary alloy on Ge(001) substrates. We have investigated the electronic and optoelectronic properties of Ge_<1-x-y>Si_xSn_y/n-Ge heterostructures for photovoltaic applications. A Ge_<1-x-y>Si_xSn_y layer with a high Sn content of 12% can be prepared with lattice matching epitaxy on Ge at a low temperature below 250 ℃. The small misfit between Ge_<1-x-y>Si_xSn_y and Ge effectively impacts on the high crystalline quality and high thermal stability of substitutional Sn atoms in Ge matrix. Engineering of the absorption energy in solar cell of Ge_<1-x-y>Si_xSn_y/n-Ge hetero-structure is also demonstrated.