A NEW RECOMBINATION MODEL FOR DEVICE SIMULATION INCLUDING TUNNELING

A new recombination model for device simulation is presented. This model includes both trap-assisted tunneling (under forward and reverse bias) and band-to-band tunneling (Zener tunneling). The model is formulated in terms of analytical functions of local variables which makes it easy to implement in a numerical device simulator. The trap-assisted tunneling effect is described by an expression that for weak electric fields reduces to the conventional Shockley-Read-Hall (SRH) expression for recombination via traps. Compared to the conventional SRH expression, the proposed model has one extra physical parameter, vis. the effective mass m*. For m* = 0.25m0 the model correctly describes the experimental observations associated with tunneling, including the distinctly different temperature behavior of trap-assisted tunneling and band-to-band tunneling. The band-to-band tunneling contribution is found to be important at room temperature for electric fields larger than 7 x 10(5) V/cm. It is shown that for dopant concentrations above 5 x 10(17) cm-3 or, equivalently, for breakdown voltages below approximately 5 V, the reverse characteristics are dominated by band-to-band tunneling.