Abstract

Three-wave mixing has been used to observe a broad range of physical phenomena at vacuum–solid, liquid–solid, and more recently even solid-solid interfaces.^1,2 The latter development is particularly exciting because it is difficult to study buried interfaces with traditional electron and photon spectroscopies. We have uses second-harmonic (SH) generation to spectroscopically probe the interface electronic structure of the ZnSe/GaAs [001] heterojunction. Our measurements reveal an unusual three-wave mixing resonance that appears to arise as a result of virtual transitions to a quantum-well (QW) state that forms locally at the buried interface. These experiments represent the first observation of this class of phenomena.

© 1992 Optical Society of America