Electronic structures calculation of Si1−xSnx compound alloy using interacting quasi-band model

We investigate energy band structures of Si_1-xSn_x compound alloy in zincblende structure using interacting qasi-band (IQB) model. The previous IQB model has been developed for three element compound semiconductors such as A_1-xB_xD. To apply IQB for Si_1-xSn_x, we here extend the IQB for four element compounds and calculate the electronic structures of virtual alloy as Si_1-xSn_xSi_1-ySn_y, where x=y. Diagonalizing a 20 × 20 non-Hermitian Hamiltonian matrix using sp3s* tight binding theory, we obtain quasi-band structures for several x. Comparing the band structures, we reveal that indirect-direct gap crossover in Si_1-xSn_x occurs around x = 0.39.