Resistive zinc oxide (ZnO) sensors play a pivotal role in detecting various gases and vapors due to their high response, low cost, stability, tunability, and simple fabrication. Hence, it is necessary to know the recent status of research in resistive ZnO sensors. The sensitivity is determined by the reactions at the surface of the nanofiber (NF); therefore, the surface area defines the foremost sensor characteristics. Electrospun metal oxide NFs exhibit a high surface area and unique electrical properties that can be tuned, and they are highly sought as the materials for resistive gas sensors. So far, various strategies are adopted to improve the sensitivity and the selectivity of ZnO NFs. This review summarizes the recent methods utilized by various researchers to improve the sensitivity of the ZnO electrospun metal oxide NF-based resistive gas sensors. Also, it discusses the influence of process parameters on the structure and morphology of ZnO NFs, the mechanism of gas sensing and highlights its improvement through advanced methods. The sensitivity of the NF has been improved through tuning the structure and morphology of NFs and doping. Further, modification of NF sensitivity through functionalization, the addition of carbon nanomaterials, and high-energy irradiation are also discussed. Based on the recent literature, the performance of doped ZnO NF for various gas sensing is highlighted. The outcome of this review gives insight to academic researchers and industry for further investigation and development in resistive gas sensors and its applications.

Semiconducting thin films of cadmium selenide have been grown by conventional thermal evaporation technique. The effect of various growth parameters like rate of deposition and deposition temperature has been studied in detail. Films deposited at room temperature are cadmium rich with segregated selenium globules. A deposition temperature of 453K has been found to yield stoichiometric, homogeneous films. The films have been analysed for optical band gap and thermal activation energies. Films of low electrical resistivity have been obtained for possible applications.

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