Single heterojunction structures for acoustic charge transfer devices

Numerical studies are reported of possible epitaxial layer structures for an acoustic charge transfer device in which charge confinement is provided by a single heterojunction. These devices were modelled to find structures providing adequate charge confinement and minimal background charge. It is found that, to avoid parasitic signals at the frequency of the surface acoustic wave, it is necessary to have minimal charge in the accumulation layer at the heterojunction interface. The level of parasitic signal obtained using a single heterojunction acoustic charge transfer device is compared with that obtained using a quantum well acoustic charge transfer device.