AlGaN/GaN heterostructure FET - Processing and parameters evaluation

Abstract

AlGaN/GaN heterostructure field effect transistors were investigated in terms of microwave and sensor applications. Heterostructure layers grown on sapphire substrates were evaluated using impedance spectroscopy measurements. The 2DEG sheet concentration of 8 × 1012 cm-2 and mobility of 1600 cm12/(Vs) were obtained. The measured I-V characteristics of the heterostructure field effect transistors devices revealed the saturated drain current 180 mA/mm and the gate pinch-off voltage-2.0 V with the transconductance 200 mS/mm. The structures have been characterized in microwave frequency range with the measured cut-off frequency of 6 GHz for 1 μm gate device. Studies of an AlGaN/GaN heterostructure Schottky diode with a catalytic Pt electrode as a hydrogen gas sensor confirmed high sensitivity of the Schottky barrier on hydrogen adsorption. Differential conductance of the Schottky diode was found to be a convenient parameter to estimate changes of the Schottky barrier height.