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

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 106μm and characterized its sensitivity at from 0.5 to 2V bias (i.e., ~5 to 100nA/μm). 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 (5min) and cost, as well as the need for cleanroom environments. [Display omitted] •Maskless (lithography-free) microfabrication was developed for creating mechanical sensors.•Laser ablation enables facile and rapid etching of underlying Si substrate to release membrane.•Electrically stable metal contact on sensor surface was achieved using direct wire bonding.•Reversible and reliable sensor operation was achieved with sensitivity (~ 5nA/μm at 0.5V and ~ 100nA/μm at 2V).