Hetero-structure solar cell made with Si and Ge layers

In this paper, we propose a four layered p-i-i-n hetero structure solar cells. The major novel element of this hetero structure is existence of two intrinsic layers, where photocurrent generation is the highest. Mature technology of fabrication of Si-Ge hetero-structures and well developed device processing methods motivated our design of Si(p)-Si(i)-Ge(i)-Si(n) solar cell. As Si and Ge are lattice matched, epitaxial growth of 4 layers could be significantly simplified. We compare our design to conventional Si (p-i-n) and Si(p)-Ge(i)-Si(p) solar cells with similar dimensions. Our modeling demonstrates open circuit voltage of 0.7V, short circuit current density of 36.8A/cm2 and moderately high total efficiency of 19.72% for a cell 75μm thick.