Surface space-charge waves in semiconductors in relation to the acoustoelectric surface-wave amplifier

A unique material combination of a non-piezoelectric semiconductor adjacent to an insulating piezoelectric can create the equivalent of a piezoelectric semiconductor and hence give rise to an equivalent acousto-electric effect. The acoustoelectric interaction occurs when fringing electric fields, created by an acoustic surface wave on the piezoelectric, interact with carriers near the surface of the semiconductor creating a traveling space-charge wave. Under certain conditions an imposed drift field can cause the space charge waves to grow and lead to amplification. Practical amplifying devices have resulted from this unique effect and material combination, and are receiving increased attention in solid-state research groups.