Epitaxial lift-off process for III-V solar cells by using porous germanium for substrate re-use

Germanium substrate re-use by porous sacrificial layer appears to be a promising approach for next generation high efficiency III- V solar cells. The morphological evolution of the double porous Ge layer upon ultra-high-vacuum annealing both experimentally and numerically was studied. We introduced the three-dimensional kinetic Monte Carlo model based on thermally activated jumps of atoms to simulate the porous Ge layer evolution during high temperature annealing driven by minimization of the total surface energy. It was demonstrated that the simulated sintering of double layer of randomly distributed Ge pores concurs quantitatively with experimental findings.