Analysis and modeling of charge transport in a GaAs CCD
Date
1991
Authors
Pennathur, Shankar
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Abstract
An analytical model is proposed to simulate charge transfer in GaAs Cermet-gate Charge-Coupled Devices (CCDs). Expressions are derived for the potential profiles under the gate electrodes. To simulate charge transfer, the values of the fringing fields under the gate electrodes are required and they are computed based on the solutions of the two-dimensional Poisson's equation. A one-dimensional transport equation is used to study charge transfer between the adjacent electrodes.
The effects of device geometry , channel dopings and profiles on the transĀfer times have been investigated . The fundamental speed limitations related to velocity saturation in GaAs CCDs are explored.
An equivalent circuit model for a GaAs CCD is developed based on the analytical model. This model includes the input and output circuits and can be simulated using SPICE as the simulator. Typical simulations using the equivalent circuit model are found to compare favourably with analytical results for a much reduced computing time. Transient simulations of the charge transport have been carried out and proved to be highly satisfactory.