A PHOTOEMISSION-STUDY OF THE BAND-STRUCTURE OF INSB(100)

Angle resolved photoemission spectroscopy with synchrotron radiation w as used to study the valence band structure of InSb (100). Normal emis sion energy distribution curves exhibit direct transitions from the va lence band maximum Gamma(8) at the Gamma-point of the Brillouin zone a nd along the [100] direction (Delta). The splitting of the valence ban d maximum along Delta into a heavy hole band Delta(5)(hh) and a light hole band Delta(5)(lh) is clearly resolved. The amount of the splittin g is found to be < 200 meV. In addition, we find transitions from the spin-orbit split valence band Gamma(7). The valence band spin-orbit sp litting at the Gamma-point is determined to be (750+/-50) meV. The dis persion behaviour of light and heavy hole bands and the spin-orbit spl it valence band as well as the resulting data for spin-orbit and light -hole/heavy-hole-band splitting of the topmost valence bands are compa red to band structures calculated by nonlocal pseudopotential and self -consistent local-density approximations.