Surface acoustic waves excited in a Si-SiO2-ZnO layered structure can produce a traveling electric field in the silicon substrate. Charges stored in the traveling potential wells can be transferred at high speed and density and with less complexity than conventional charge coupled devices. The monolithic structure under investigation for the surface acoustic wave charge transfer device consists of a silicon substrate, a thin silicon dioxide insulating layer on top of which a ZnO piezoelectric film is deposited by sputtering. The surface acoustic waves are excited by interdigital transducers. The signal charge is injected into traveling potential wells that travel with the velocity of sound. The presence of a thin shorting plate placed on the ZnO film, over the charge transfer region, can enhance the acousto-electric potential at the Si-SiO2 interface, thus resulting in a more efficient device. An 80 MHz, 2p-second surface acoustic wave charge coupled device has successfully been fabricated. An optical application utilizing such a structure is proposed. It can be used in place of a conventional interline transfer design. Surface acoustic waves are launched before the charges are transferred from the sensor region to the transport region.
N. A. Papanicolaou,
H. C. Lin,
H. F. Benz,
"A Monolithic Surface Acoustic Wave Charge Transfer Device And Its Applications," Optical Engineering 19(4), 194587 (1 August 1980). https://doi.org/10.1117/12.7972563