PHOTOELECTRIC STUDY OF BETA-FESI2 ON SILICON - OPTICAL-THRESHOLD AS AFUNCTION OF TEMPERATURE

Investigation of the photoelectric properties of several metal/beta-Fe Si2/Si heterostructures is presented. For thin silicide samples (200 a ngstrom), the photocurrent follows a Fowler's law with a threshold PHI 1 lower than the silicide band gap E(g). For thicker silicide samples (2500 angstrom), the behavior of the photocurrent is different because the optical absorption within the silicide can no longer be neglected : a maximum of the photocurrent is observed Instead at E(g). The varia tions of E(g) and PHI1 with temperature are compellingly similar and s how the strong effect of the electron-phonon coupling. We suggest that the threshold PHI1 corresponds to transitions between a trap localize d near the heterojunction and the silicide conduction band.