Characteristics of the overlaid charge-coupled device

A novel charge-coupled device structure (the overlaid CCD) is described. It operates by transferring charge packets on two distinct levels which are overlaid in the semiconductor bulk. This bulk-integrated device has an increased density per unit area and a reduced driving power consumption per bit compared to conventional buried-channel CCD´s still enjoying bulk-channel operation. Furthermore, the overlaid CCD can be employed to perform certain operations that could otherwise be performed only at greater expense. The price to be paid is a smaller charge-carrying capacity of the deeper laying transfer level. The operational characteristics of the overlaid CCD are investigated by means of analytic, as well as two-dimensional numerical calculations. Emphasis is laid upon assessing the distinguishing features of the device and evaluating the relative influences of the design parameters on the operational performances.