Bremsstrahlung Isochromat Studies of Conduction-Band States in Gase

Abstract Using bremsstrahlung isochromat spectroscopy, we have directly studied of the conduction band density of states of the prototypical layer compound GaSe. We find two main features in the lower conduction band density of states, in qualitative agreement with core-level reflectivity data. However, there is a large discrepancy between the energy positions of the optical and BIS peaks. This discrepancy is discussed in terms of excitonic effects and of self-energy corrections.