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This paper presents the performance of a highly selective ethanol sensor based on MoS-functionalized porous silicon (PSi). The uniqueness of the sensor includes its method of fabrication, wafer scalability, affinity for ethanol, and high sensitivity. MoS nanoflakes (NFs) were synthesized by sulfurization of oxidized radio-frequency (RF)-sputtered Mo thin films. The MoS NFs synthesis technique is superior in comparison to other methods, because it is chip-scalable and low in cost. Interdigitated electrodes (IDEs) were used to record resistive measurements from MoS/PSi sensors in the presence of volatile organic compound (VOC) and moisture at room temperature. With the effect of MoS on PSi, an enhancement in sensitivity and a selective response for ethanol were observed, with a minimum detection limit of 1 ppm. The ethanol sensitivity was found to increase by a factor of 5, in comparison to the single-layer counterpart levels. This impressive response is explained on the basis of an analytical resistive model, the band gap of MoS/PSi/Si, the interface formed between MoS and PSi, and the chemical interaction of the vapor molecules and the surface. This two-dimensional (2D) composite material with PSi paves the way for efficient, highly responsive, and stable sensors.

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A high speed efficient broadband photodetector based on a vertical n-MoS2/p-porous silicon heterostructure has been demonstrated. Large area MoS2 on electrochemical etched porous silicon was grown by sulphurization of a sputtered MoO3 thin film. A maximum responsivity of 9 A/W (550–850 nm) with a very high detectivity of ∼1014 Jones is observed. Transient measurements show a fast response time of ∼9 μs and is competent to work at high frequencies (∼50 kHz). The enhanced photodetection performance of the heterojunction made on porous silicon over that made on planar silicon is explained in terms of higher interfacial barrier height, superior light trapping property, and larger junction area in the MoS2/porous silicon junction.

Wearable dosimeters form an essential part of the personnel protection scheme in work spaces such as defence, nuclear establishments, and medical fields with radiation hazard. In the current scenario where use of high energy ionizing radiation sources (nuclear sources) is indispensable, the need of radiation detectors is mandatory for measuring the dose received by the person exposed in his work space and also measure the dose for patients where nuclear radiation is used for treatment. Wearable dosimeters need to have some special requirements apart from being accurate, precise, and robust. These need to be light in weight and should cause no harm to the human body while it is touching the body or apparels. This paper comprises an introduction to dosimeters, key characteristics, important techniques used for detection of neutrons and X‐rays and also mentions about a few potential companies involved in developing wearable dosimeters in these application areas. The techniques have been collated, described, compared and the need to detect neutrons and X‐rays has been expressed keeping in mind the demand from the defence and medical disciplines. This review also contains artificial intelligence and internet of things which form the basis of trending and upcoming wearable dosimeters.

Synthesis of orthorhombic (α) MoO 3 nano-flakes by dry oxidation of RF sputtered Mo thin film is presented. The influence of Mo thickness variation, oxidation temperature and time on the crystallographic structure, surface morphology and roughness of MoO 3 thin films was studied using SEM, AFM, XRD and Raman spectroscopy. A structural study shows that MoO 3 is polycrystalline in nature with an α phase. It was noticed that oxidation temperature plays an important role in the formation of nano-flakes. The synthesis technique proposed is simple and suitable for large scale productions. The synthesis parameters were optimized for the fabrication of sensors. Chrome gold-based IDE (interdigitated electrodes) structures were patterned for the electrical detection of organic vapors. Sensors were exposed to wide range 5-100 ppm of organic vapors like ethanol, acetone, IPA (isopropanol alcohol) and water vapors. α-MoO 3 nano-flakes have demonstrated selective sensing to acetone in the range of 10-100 ppm at 150 °C. The morphology of such nanostructures has potential in applications such as sensor devices due to their high surface area and thermal stability.

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