Interface quantum well states observed by three-wave mixing in ZnSe/GaAs heterostructures

Three-wave mixing was used to spectroscopically probe the interface electronic structure of a buried ZnSe/GaAs[001] heterointerface from 1.3 to 4.3 eV. An unusual resonance at 2.72 eV was observed and assigned to a virtual transition between the valence band of ZnSe and a quantum well state at the buried heterointerface. This assignment was confirmed by experiments that combine three-wave mixing with photoinduced band bending. The experiments also indicate the resonance may be a useful probe of defects at the buried interface.