INVESTIGATION OF THE PROCESS OF INTERNAL PHOTOEMISSION IN PLATINUM SILICIDE SCHOTTKY BARRIER DIODES (DETECTOR, INFRARED).

Abstract

In this work, the theory of internal photoemission is reviewed and extended for the special case of platinum silicide Schottky barrier infrared photodiodes. Vickers' model of hot-electron-mode photodetection is recast in terms of hot-holes, and the effects of carrier energy loss due to phonon collisions, as well as the depletion of the occupation of the emitting states due to emission are included. The optical absorption of the Schottky diodes is measured and used to relate the quantum efficiency of the diodes to the internal yield as calculated from the model. By including the effects of the carrier energy loss due to phonon collisions and the depletion of the occupation of the emitting states in the model, one can resolve previously unexplained anomalies in the photoresponse data (the shape of the Fowler plots, the absolute magnitude of the yield, and the difference between the optical and thermal barriers). Independent estimates are obtained for the mean-free-path between hot-hole/phonon, hot-hole/cold-electron, and hot-hole/imperfection collisions as well as the mean phonon energy, mean transmission coefficient across the Schottky barrier, and the Fermi energy. The model is found to be in excellent agreement with the experimental data for parameter values consistent with those reported in the literature. Some degree of correlation is found to exist between the one free variable for each diode and the processing used for that diode. Namely, the temperature of the substrate during deposition is correlated with the value of the mean-free-path between imperfection scattering events.