Pt-AlGaN/GaN HEMT-sensor layout optimization for enhancement of hydrogen detection

Abstract

This paper reports on the layout optimization of Pt-AlGaN/GaN HEMT-sensors for enhancing hydrogen sensor performance. Sensors with gate width and length ratios W <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> /L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> from 0.25 to 10 were designed, fabricated and tested for the detection of hydrogen gas at 200 °C. Sensitivity, sensing current variation and transient response are directly related to the sensor gate electrode W <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> /L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> ratio. The obtained results demonstrated a 217 % increase in sensitivity and 4630 % increase in sensing current variation at 500 ppm H2 for a W <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> /L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> from 0.25 to 10. In addition, the detection limit was lowered to 5 ppm. Transient characteristics demonstrated faster sensor response to H2, but slower recovery rates with increasing ratio.