Abstract

The combination of photoexcitation and second-harmonic generation (PSHG) has recently been demonstrated to be a useful probe of band bending and electronic traps at semiconductor heterojunctions.¹ PSHG differs from most other modulation spectroscopies²⁴ as a result of the high sensitivity to symmetry inherent in SH probes. Most generally, it offers the possibility of probing surfaces and interfaces that are perturbed by local electric fields or stresses without the use of contacts. In this contribution we report our observations on an enhancement of the bulk second-order susceptibility in GaAs as a result of reduced surface band bending. This reduction is produced by photoexcited carriers in the depletion region.

© 1993 Optical Society of America