Single-phase, unidirectional transducer design for charge transport devices

Expressions for calculating the per-stripe reflectivity of aluminum stripe and grooved reflectors as a function of stripe width and thickness are given. These results are used to predict the performance of unidirectional SAW (surface acoustic wave) transducers on gallium arsenide substrates for ACT and HACT (heterojunction acoustic charge transport) applications. The objective is to build the transducers using the same materials used for the NDS (nondestructive sense) Schottky barriers in (H)ACT devices, minimizing the number of photolithographic steps required and maintaining SAW equiphase front alignment to the NDS structures across the device´s channel width. In turn, the optimization of the materials systems for large reflectivity in the SAW transducer structure dictates that the NDS structures be designed to minimize net acoustic reflections by these taps in order to maintain the low acoustic standing wave ratio required for high charge transfer efficiency