Preparation of porous InAlGaN/Si(1 1 1) by photoelectrochemical etching for high performance hydrogen gas sensors at room temperature

• Porous InAlGaN/Si(1 1 1) was successfully fabricated by photoelectrochemical etching.
• Porous gas sensors showed higher sensitivity than the non-porous gas sensor.
• Sensitivity of porous gas sensors increased as pore density increased.
• The porous gas sensor had response and recovery times of 13.8 s and 88.4 s, respectively.
• Current response of porous gas sensor increased with hydrogen flow rate.

This paper describes the development of gas sensors based on platinum (Pt) Schottky contact on porous InAlGaN for hydrogen gas sensing. Porous InAlGaN samples were successfully fabricated by photoelectrochemical etching for different etching durations. Pore density and surface roughness increased with etching duration. Pt Schottky contacts which acted as the catalytic layer, were then deposited on all porous InAlGaN samples and a non-porous InAlGaN sample for comparative study. The effects of porous structure on the performance of the hydrogen gas sensors were investigated. The porous InAlGaN gas sensors exhibited better performance upon introduction of 0.1% H2 in N2 gas relative to the non-porous InAlGaN gas sensor. The sensing response of the porous InAlGaN gas sensors increased as the pore density and surface roughness increased. The sensing response of the optimum gas sensor (etched for 10 min) was about 6.9 higher than that of the non-porous InAlGaN gas sensor, with response and recovery times of 13.8 s and 88.4 s, respectively, at room temperature. Furthermore, the current response increased gradually with hydrogen flow rate for this sample.

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