Monte Carlo modeling of electron transport in repeated overshootstructures

Repeated velocity overshoot has been proposed as a way of obtaining high average velocities over significant distances in semiconductor devices. The potential of this concept is examined using a fully-self-consistent particle-field Monte Carlo simulation. Numerical results are presented for realistic periodic overshoot structures for a range of bias conditions and operating temperatures of 77 and 300 K. Local velocity overshoot peaks are observed in the simulated structures, but the average carrier velocity and current at each bias point are in all cases less than those associated with transport in bulk material at the same bias point. The physical mechanisms underlying this result are analyzed. It is found that ensemble (diffusion) effects, which were neglected in the original proposal of the repeated overshoot concept, strongly influence the results that are achievable in practice     

An ion-implantation model incorporating damage calculations incrystalline targets

A computer simulation for modeling ion implantation which incorporates the effects of channeling and damage is discussed. The simulation calculates the trajectories of implanted ions through an idealized crystal structure. Secondary generation is modeled using a damage threshold energy. The concentration of interstitials which results is used as a measure of the damage sustained by the target. The accumulated damage is used as a criterion for whether the substrate is treated as amorphous or crystalline. Modeling the crystalline-to-amorphous transition in this manner enables simulation of dose-dependent implantation. The model accounts for temperature-dependent self-annealing using an empirically determined temperature-dependent damage threshold