Abstract
Photoreflectance (PR) spectroscopy has been performed for the singlet exciton system of g -ZnP 2 in order to investigate fine structure of the higher exciton states. The PR spectrum shows clear structure at each exciton level with large modulation amplitude. It is shown that the mechanism by which the PR signal is produced is electroreflectance due to the periodic cancellation of the built-in surface electric field by photoexcited carriers. A high-resolution PR spectrum obtained by using a Ti:sapphire laser as a probe light reveals the higher members of singlet excitons up to n =6.