A High Sensitivity and Linearity AlGaN/GaN SBD Thermal Sensor With Partially Recessed AlGaN Barrier Layer Near the Pt Anode

An AlGaN/GaN heterostructure based Schottky barrier diode (SBD) temperature sensor with partially recessed AlGaN barrier layer near the Pt anode and 40 nm SiO2dielectric under the field plate is proposed for high sensitivity and linearity thermal sensing. The partially thinned AlGaN barrier layer and the 40 nm dielectric with a high work function Pt anode metal collectively result in a lower two-dimensional electron gas (2DEG) density with a higher Schottky barrier and a wider depletion region, leading to a lower tunneling current with a higher thermal sensitivity and linearity below the turn on voltage. It is experimentally revealed that the SBD with 3 nm residual AlGaN layer demonstrated the highest sensitivity of 3.75 mV/K with a linearity of 0.997 at 8×10-6A. The systemic TCAD analysis was conducted to reveal the effects of the anode metal work function and the AlGaN barrier thickness towards the thermal sensing performance of the SBD. This work explores the optimum conditions to reduce the total tunneling current for the AlGaN/GaN based thermal sensors and shows a great potential for high performance thermal sensing applications in AlGaN/GaN heterostructure based power ICs without the introduction of p-GaN.