MODELLING OF THE ELECTRON-BEAM-INDUCED CURRENT AT A METAL-p-Si SCHOTTKY CONTACT : COMPARISON WITH EXPERIMENT

Abstract
The Electron-Beam-Induced Current (EBIC) of a Schottky barrier irradiated by an electron beam perpendicular to its surface, is calculated. The continuity equation is solved for Everhart and Hoff's generation function, which applies to the case of silicon. In the depleted zone, drift and diffusion of carriers are taken into account. Recombination of carriers is introduced in the neutral zone in terms of minority carrier life time, and at the metal-semiconductor interface in terms of the Shockley-Read recombination rate. It is shown how a simple formulation can be obtained in the two extreme situations of small and strong excitation. The influence of the carrier collection through an oxide layer at the metal-semiconductor interface is considered. The variation of the collection efficiency as a function of the electron beam energy is given for different values of the interface recombination coefficient and of the diffusion length of minority carriers. These results are compared to those obtained by applying Wu and Wittry's model to silicon. The present model allows a satisfactory interpretation of experimental data obtained on Al-p-Si Schottky contacts.