Quantum size effect on optical absorption edge in thin antimony films

The quantum size effect in thin antimony films grown along (111) direction on a GaSb substrate is studied based on a simple model. The critical film thickness, at which the semimetal-semiconductor transition takes place, is determined. It is proposed that the optical experiments can be used to measure the critical thickness since the dependence of optical transition on thickness in the semimetal region is very different from that in semiconductor region.