Lithography-free microfabrication of AlGaN/GaN 2DEG strain sensors using laser ablation and direct wire bonding

Abstract

This work presents a simple and rapid lithography-free (i.e., maskless) microfabrication process for strain-sensitive aluminum gallium nitride (AlGaN)/GaN sensors. We microfabricated an AlGaN/GaN strain sensor through laser ablation of the underlying Si (111) substrate and direct bonding of aluminum wires to the sensor surface, creating a Schottky contact to the two-dimensional electron gas (2DEG). We measured the sensor's current-voltage operation while displacing the center of the membrane up to approximately 106 pm and characterized its sensitivity at from 0.5 to 2 V bias (i.e.,similar to 5 to 100 nA/mu m). This work advances the development of AlGaN/GaN-on-Si microelectronics (e.g., pressure sensors, accelerometers, and gyroscopes) using the simplified fabrication process, which eliminates lithography, metallization, and etching, and reduces the manufacturing time (5 min) and cost as well as the need for cleanroom environments.