Electron injection into thin insulating and luminescent films on silicon

Abstract

This thesis describes electron injection into thin films of thermally grown SiO(_2) and also Zn(_2)SiO(_4):Mn. Electrons are accelerated to high energies in the depletion field of a reverse biased, shallow (l000 Ǻ deep), planar p-n(_+) junction, and directed towards the silicon and thin film interface. The injection process is aided by the additional application of an electric field across the thin films. The form of the injected current dependence on the field applied across the films and with junction avalanche current is found to be consistent with electron injection from localised microplasmas within the shallow junction. The experimental results indicate that there is a near exponential rise in the injected current with increasing junction current. Previous explanations for similar dependences are shown to have several deficiencies when applied to the present structures. A new model of electron injection is proposed which is based on microplasma switching probabilities. Numerical approximations when applied to the microplasma injection model are shown to give acceptable agreement with experimental results. The fabrication of the shallow junction injection structures is described in detail and also the thin film formation, techniques. A proposed injection structure which should give a more uniform electron injection is also described.