Ultrahigh-frequency surface acoustic wave generation for acoustic charge transport in silicon

Abstract

We demonstrate piezo-electrical generation of ultrahigh-frequency surface acoustic waves on silicon substrates, using high-resolution UV-based nanoimprint lithography, hydrogen silsequioxane planarization, and metal lift-off. Interdigital transducers were fabricated on a ZnO layer sandwiched between two SiO2 layers on top of a Si substrate. Excited modes up to 23.5 GHz were observed. Depth profile calculations of the piezoelectric field show this multilayer structure to be suitable for acoustic charge transport in silicon at extremely high frequencies with moderate carrier mobility requirements.