In the last two decades, GaN nanostructures of various forms like nanowires (NWs), nanotubes (NTs), nanofibers (NFs), nanoparticles (NPs) and nanonetworks (NNs) have been reported for gas sensing applications. In this paper, we have reviewed our group’s work and the works published by other groups on the advances in GaN nanostructures-based sensors for detection of gases such as hydrogen (H₂), alcohols (R-OH), methane (CH₄), benzene and its derivatives, nitric oxide (NO), nitrogen dioxide (NO₂), sulfur-dioxide (SO₂), ammonia (NH₃), hydrogen sulfide (H₂S) and carbon dioxide (CO₂). The important sensing performance parameters like limit of detection, response/recovery time and operating temperature for different type of sensors have been summarized and tabulated to provide a thorough performance comparison. A novel metric, the product of response time and limit of detection, has been established, to quantify and compare the overall sensing performance of GaN nanostructure-based devices reported so far. According to this metric, it was found that the InGaN/GaN NW-based sensor exhibits superior overall sensing performance for H₂ gas sensing, whereas the GaN/(TiO₂–Pt) nanowire-nanoclusters (NWNCs)-based sensor is better for ethanol sensing. The GaN/TiO₂ NWNC-based sensor is also well suited for TNT sensing. This paper has also reviewed density-functional theory (DFT)-based first principle studies on the interaction between gas molecules and GaN. The implementation of machine learning algorithms on GaN nanostructured sensors and sensor array has been analyzed as well. Finally, gas sensing mechanism on GaN nanostructure-based sensors at room temperature has been discussed.

中文翻译：

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氮化镓（GaN）纳米结构及其气敏特性：综述。

在过去的二十年中，已经报道了各种形式的GaN纳米结构，例如纳米线（NWs），纳米管（NTs），纳米纤维（NFs），纳米颗粒（NPs）和纳米网络（NNs）用于气体传感应用。在本文中，我们回顾了我们小组的工作以及其他小组发表的有关基于GaN纳米结构的传感器（用于检测诸如氢气（H ₂），醇（R-OH），甲烷（CH ₄））的研究进展。，苯及其衍生物，一氧化氮（NO），二氧化氮（NO ₂），二氧化硫（SO ₂），氨（NH ₃），硫化氢（H ₂ S）和二氧化碳（CO ₂）。总结并列出了重要的传感性能参数，例如不同类型传感器的检测极限，响应/恢复时间和工作温度，以提供全面的性能比较。已经建立了一种新的度量标准，即响应时间和检测极限的乘积，以量化和比较迄今为止报道的基于GaN纳米结构的器件的整体传感性能。根据该度量标准，发现基于InGaN / GaN NW的传感器在H ₂气体感测方面表现出优异的整体感测性能，而基于GaN /（TiO ₂ –Pt）纳米线-纳米团簇（NWNCs）的传感器更适合乙醇感应。GaN / TiO ₂基于NWNC的传感器也非常适合TNT感测。本文还回顾了基于密度泛函理论（DFT）的气体分子与GaN之间相互作用的第一性原理研究。还分析了机器学习算法在GaN纳米结构传感器和传感器阵列上的实现。最后，讨论了基于GaN纳米结构的传感器在室温下的气体传感机理。