Chapter 6 - The Role of Boundary Conditions in Near- and Submicrometer-Length Gallium Arsenide Structures

Abstract

Publisher Summary This chapter discusses the role of boundary conditions in near- and submicrometer-length Gallium Arsenide structures. The major technological interest in transient transport arises from the predictions of unusually high mean carrier velocities. The initial discussions of these high velocity values was for uniform space charge distributions, but the results were thought to be relevant for those situations where the mean carrier energy was insufficient to lead to substantial electron transfer in gallium arsenide. Thus, the trend developed toward submicrometer-scale devices. The complication that arises in submicrometer devices is that the boundary conditions will be the determinant as to whether high velocities will be attained. Additionally, the constraints of current continuity dictate whether high velocities will be accompanied by high carrier densities. Transient overshoot in submicrometer structures reflects the presence of velocity overshoot and displacement current effects. It is not possible, in a simple way, to separate the two, with the result that transient measurements of overshoot require extreme care in interpretation. Relaxation times to steady state are dominated by the dominating boundary; for example, either the metal contact or the critical interface.