AlGaN/GaN Field-Effect Surface Acoustic Wave Filters with >40-dB Isolation for Monolithic Integration with HEMTs

Abstract

Microwave monolithic integrated circuits (MMICs) equipped with high-Q passive devices are likely to play an essential role in future wireless systems. Although surface acoustic waves (SAWs) have been widely used for realizing high-Q passive devices, monolithic integration of conventional insulator-based SAW devices and electron devices is not practical. Noting that group-IH nitrides are a promising material for such integration due to their semiconducting properties and large piezoelectricity, we previously fabricated SAW filters on GaN layers on (0001) sapphire substrates [1, 2]. In this paper, we report on characteristics of SAW filters with interdigital transducers (IDTs) composed of ohmic and Schottky contacts and those of HE\Ts on AlGaN/GaN heterostructures, and discuss the possibility ofmonolithically integrating SAW and electron devices.