Relaxation process of band-edge exciton in layered crystalline GeSe2

Relaxation processes of the photoexcited states in layered crystalline GeSe 2 are studied by time-resolved photoluminescence measurement. Two photolumi nescence bands, P1 and P2, are clearly resolved from their decay kinetics. It is found that one of the relaxation pathways to the P2 band arises from a band-edge exciton state. The P2 band shows no polarization dependence, in spite of the fact that the photoexcitation of the exciton shows a strongly anisotropic optical character, We discuss the relaxation process on the ba sis of the luminescence characteristics and the structural model of the ban d-edge exciton quasi-localized at edge-sharing tetrahedra, (C) 2000 Elsevie r Science B.V. All rights reserved.