Ultrafast H_2 gas nanosensor for ppb-level H_2 gas detection based on GaN honeycomb nanonetwork

摘要

Material architecture design plays a crucial role in developing gas sensors. GaN has been proposed as a promising material for H_2 gas sensor. However, it is subject to long response time and large low limit of detection (LOD).via spherical metal pattern technology, honeycomb can be created in GaN nanostructure but has yet to be explored. Herein, the GaN honeycomb nanonetwork was utilized to fabricate a field effect transistor (FET) type hydrogen (H_2) gas nanosensor and its H_2 gas sensing performances were systematically investigated. Through the combination of the novel honeycomb nanonetwork with the field effect modulation, we demonstrate high performance H_2 gas sensor with wide detection concentration range, fast response, and small LOD. It is worth noting that the response time for H_2 gas is very fast, as short as ≤3 s. Most importantly, the LOD for this FET type sensor is as small as ～ 34 ppb. Density functional theory (DFT) calculation was utilized to study the H_2 gas sensing mechanism. Significant reduction of Schottky barrier and improvement of the tunneling probability of the Pt-GaN metal-semiconductor interface were observed. Finally, a model is proposed to explain the H_2 gas sensing mechanism.