A simple Monte Carlo model for prediction of avalanche multiplication process in Silicon

Abstract

A Simple Monte Carlo model has been developed to model the avalanche characteristics of Silicon. Good agreement with experimental results from Silicon p+-i-n+ diodes with i-regions ranging from 0.082 to 0.26 μm, an n+-i-p+ diode with an i-region of 0.82 μm and a p+n diode was obtained. Therefore our model can be used to model the avalanche process in diodes with varying electric field profiles. We also studied the competing effects of the ratio of electron to hole ionization coefficients and the dead space on excess noise factor, by varying these parameters in our simulations of ideal p+-i-n+ diodes with avalanche regions width of 0.05 to 0.3 μm to cover the electric field range in the measured devices. As avalanche region width reduces from 0.3 to 0.05 μm, the electron to hole ionisation coefficient ratio decreases from 3.42 to 1.23 while the dead space to avalanche width ratio increases from 0.19 to 0.49 for electrons. The former increases the excess noise while the latter suppresses the avalanche noise such that on balance, a weak dependence of excess noise on the avalanche width for w < 0.3 μm was observed in these p+-i-n+ diodes, consistent with the excess noise results reported in thin Silicon p+-i-n+ diodes.