Surface Acoustic Wave Excitation on SF6 plasma treated AlGaN/GaN heterostructure

Abstract

Nowadays, there is an increasing interest to generate the Surface Acoustic Wave (SAW) directly on AlGaN/GaN heterostructure material system that defines a two-dimensional electron gas (2DEG) of the high electron mobility transistors (HEMTs). However, the direct interaction of SAW with free carriers of 2DEG prevents the acousto-electric transduction in the interdigital transducers (IDTs) due to the additional insertion losses. Therefore, in this work, we present a new approach in forming of interdigital (SAW) structures on AlGaN/GaN heterostructure to be applied for chemical sensors technology. The new approach uses a selective self-aligned SF6 plasma treatment of the AlGaN/GaN heterostructure to modify 2DEG density thus enabling the redistribution of the E-field and reduction of the peak field in the range of SAW structures. It enables to control these losses, so SAW propagation in the AlGaN/GaN can be observed