Monte Carlo Simulations of Ballistic Structures
It is well known that velocities much higher than those of steady state can be realized in specific conditions. Assuming first an homogeneous field in the semiconductor, the maximum average velocity which could be achieved for carriers over a distance d in GaAs material is numerically calculated by Monte Carlo methods in the case of overshoot and ballistic motions.
The potential of such velocity overshoot or ballistic motion in real submicronic devices is then assessed. It is shown that due to spatial non-uniformity, additional phenomena occur which reduce the velocity of the carriers, especially in ballistic motion. Therefore, it appears that simplified methods based on studies versus time could not be used and only microscopic space simulations should be employed.
We finally study two examples of real submicronic devices that roughly illustrate these overshoot and ballistic regimes. The effect of the application of the magnetic field is also investigated.
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