Electronic structure and optical properties of β-FeSi2(100)/Si(001) interface at high pressure

The electronic structure and optical absorption properties of the β-FeSi2(100)/Si(001) interface are investigated by first-principle calculation at high pressure. As the pressure increases, the optical gap decreases sharply, reaches a minimum, and then increases slowly. Structural analysis reveals that the Si(001) slab partially offsets the pressure exerted on the β-FeSi2 (100) interface, thus downshifting the lowest unoccupied electronic states of the interface and decreasing the optical gap. As the pressure increases further, this offsetting effect weakens and the optical gap increases again gradually. Hence, a high pressure plays an important role in the optical behavior.