Computer simulations of charge transport in GaAs cermet-gate CCDs are discussed. A finite difference scheme is used to simulate charge evolution between successive clock phases. Epi-grown and ion-implanted channels are considered. It is shown that charge transport and hence the transfer inefficiencies of these devices depend on the relative importance of the drift field and the self-induced field more than the diffusion contribution. The one-dimensional scheme used for the simulation of charge transfer is simple and computationally less intensive than a rigorous two-dimensional approach, but is qualitatively as effective.>

Calculations of threshold voltages and their variations with respect to fluctuations in the substrate dopant density and the channel depth were performed for a recoil-implanted profile of a GaAs MESFET. It was observed that for these very shallow channels, the range of threshold voltages obtained was considerably smaller for different nitride thicknesses and there was a noticeable reduction in the sensitivity of the threshold voltage to fluctuations in the substrate parameters. The implant depth was the crucial parameter in the determination of the threshold voltage and its sensitivity, although in recoil implantation the surface dopant density appeared to be the dominant parameter.>