Electrically driven nanoscale acoustic source based on a two-dimensional electron gas

Acoustic emission by a modulated two-dimensional electron gas (2DEG) is studied analytically, numerically, and experimentally. Optical reflectance measurements provide the full acoustic spectrum emitted by a modulated GaN-based 2DEG, including various surface acoustic wave (SAW) modes that propagate with different polarizations and penetration depths within the epitaxial layer structure. A 2DEG is shown to provide a source of SAWs that is several orders of magnitude more intense than an interdigital transducer (IDT) of the same chip area. Furthermore, a 2DEG SAW source is shown to have the ability to switch between different acoustic modes based on applied DC bias conditions. (C) 2013 AIP Publishing LLC.