Abstract
Acoustoelectric devices convert acoustic energy to electrical energy and vice versa. Devices working at much higher acoustic frequencies than those currently available have potential scientific and technological applications, for example, as detectors in phononics experiments and as transducers in bulk acoustic wave filters at terahertz (THz) frequencies. Here we demonstrated an active acoustoelectronic device based on a GaAs heterostructure: an acoustically gated transistor or phonotransistor. Instead of being controlled in the conventional manner by an electrical signal applied to a metallic or semiconductor gate as in a high electron mobility transistor (HEMT), the drain-source current was controlled by a bulk sub-THz acoustic wave passing through the channel in a direction perpendicular to the current flow.
Highlights
Acoustoelectric devices convert acoustic energy to electrical energy and vice versa
Based on the results above, we propose that the observed response is due to the acoustic wave inducing a decrease in the 2DEG carrier density as it propagates through the heterostructure
Measurements of the dependence of the acoustically induced signal on the pump fluence and the temperature both pointed to the 2DEG being most sensitive to the acoustic waves of frequency >150 GHz
Summary
Acoustoelectric devices convert acoustic energy to electrical energy and vice versa. Devices working at much higher acoustic frequencies than those currently available have potential scientific and technological applications, for example, as detectors in phononics experiments and as transducers in bulk acoustic wave filters at terahertz (THz) frequencies. Any of the devices in which the control of electronic transport by coherent phonons has been demonstrated, e.g., Schottky diodes[13], resonant tunnelling diodes[20] and superlattices[21], could form the basis of a “phonodiode” detector These devices have no capacity for gain, and the development of a “phonotransistor” with the potential for a gain effect has the potential to improve the sensitivity of phonon detection and to facilitate the integration of coherent phonon signals into electrical circuits. To achieve the creation of a phonotransistor, this work investigates coherent phonon effects in high electron mobility transistors (HEMTs) based on the twodimensional electron gas (2DEG) formed in a semiconductor heterojunction. These devices are interesting for terahertz (THz) phonon applications because they have been shown to work at high frequencies. An amplifier circuit based on HEMT devices holds the Guinness world record for the highest frequency amplifier, having been shown to measure at a gain of 9 decibels at 1 THz22
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