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 used 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 state that forms locally at the buried interface. These experiments represent the first observation of this class of phenomena.

© 1992 IQEC