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 Wg/Lg 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 Wg/Lg ratio. The obtained results demonstrated a 217 % increase in sensitivity and 4630 % increase in sensing current variation at 500 ppm H2 for a Wg/Lg 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.

Hydrogen sulfide detection properties of Pt-gated AlGaN/GaN HEMT-sensor

“…A Silicon carbide FET with Pt and Ir gates was also shown to sense H2S, however signal saturation was observed at low concentration of 6~8 ppm under 5% oxygen atmosphere [32]. Recently we presented successful sensing of H2S with Pt-AlGaN/GaN HEMT based sensor [33]. In this work, we further expand on our preliminary results by comprehensively studying DC and transient characteristics at different temperatures and H2S concentrations in dry air atmosphere.…”

“…1. The gate dimensions exposed to gas were 40 μm × 400 µm and the gate-source and gate-drain spacing was 6 µm, based on our earlier report [36]. After fabrication, the wafers were diced and individual devices were wire bonded to ceramic substrates for high temperature measurements.…”

A comprehensive review of gallium nitride (GaN)-based gas sensors and their dynamic responses

“…AlGaN/GaN-based sensors with gate electrodes of different W g /L g ratios (e.g., 1, 5, 7, 10, and 100) have been demonstrateded. 84,95,96,108 Sokolovskij et al 28,84 revealed that the dimensions of the gate electrode directly influence the sensitivity, current variations, and transient response of the sensor. As W g /L g was increased from 0.25 to 10, a 217% increase in the sensitivity and a 4630% increase in variations in the sensing current of the sensor were recorded under 500 ppm H 2 .…”

Readout Integrated Circuit for Small-Sized and Low-Power Gas Sensor Based on HEMT Device

“…Therefore, it is important to build a sensing device with high sensitivity. Since semiconductor-based HEMTs can easily achieve high sensitivity with small sizes, they are widely used in sensor systems [ 6 , 7 , 8 ]. HEMTs comprise a heterojunction structure, with wide and narrow bandgap layers.…”