A Novel Discrete GaN/AlGaN/GaN-Based Schottky Diode Thermal Sensor With a Sensitivity Up to 13.3 mV/K

A novel discrete GaN/AlGaN/GaN heterostructure-based Schottky barrier diode (SBD) thermal sensor is proposed, demonstrating a very high thermal sensitivity of 13.3 mV/K with a linearity of 0.992 at 10-5 A for 45 nm GaN cap over a temperature range of 298 K to 573 K using Pt as the anode. Samples with different GaN cap thickness were fabricated to obtain variable temperature sensitivities with linearity above 0.99. A Schottky diode model with an applied bias (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>D</i></sub>) dependent equivalent Schottky barrier height (Φ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>B</i></sub>) is proposed to explain the much higher temperature sensitivity than the conventional AlGaN/GaN SBD thermal sensor. The TCAD simulation clearly confirms the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>D</i></sub> dependent Φ<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>B</i></sub> and reveals its effect on amplifying the thermal sensitivity， and the fitting curves calculated by the equivalent equation fits well with the simulation data. This work demonstrates an area and cost-saving solution for the high performance AlGaN/GaN-based temperature sensor applications.