Voltage-controlled NiO/ZnO p–n heterojunction diode: a new approach towards selective VOC sensing

Abstract

Metal oxide resistive gas sensors suffer from poor selectivity that restricts their practical applicability. Conventional sensor arrays are used to improve selectivity which increased the system complexity. Here, we have proposed a novel NiO/ZnO-based p–n junction single-diode device for selective sensing of several volatile organic compounds (VOCs) simultaneously by tuning bias voltage. The operating voltage was varied between 3 and 5 volts to achieve selective sensing of 2-propanol (19.1 times for 95 ppm with response and recovery times of 70 s and 55 s respectively‚ at 3 volts), toluene (20.1 times for 95 ppm with response and recovery times of 100 s and 60 s respectively, at 4 volts), and formaldehyde (11.2 times for 95 ppm with response and recovery times of 88 s and 54 s respectively, at 5 volts). A probable mechanism of the tunable selectivity with operating bias voltage due to increase in surface carriers with increasing voltage was hence put forth. Thus, this device may play an important role to develop future selective multiple VOC sensor thereby replacing standard sensor arrays.

High-Performance Oxide-Based p–n Heterojunctions Integrating p-SnOx and n-InGaZnO

“…41 As fundamental units in modern microelectronics, p−n junctions are widely used in electronic and optoelectronic applications such as junction transistors, 42 solar cells, 43 photodetectors, 44 electronic memory elements, 45 and chemical sensors. 46 Although single-crystalline bulk materials such as Si and GaAs have dominated the semiconductor junction industry and their applications, because of the demands of mild thermal budget processing, new or additional functionalities required for specific applications (e.g., transparency, catalytic activities), and low-cost manufacturing processes, oxide semiconductor thin films have been garnering a large amount of attention in recent years due to the results of enhanced understanding and processability of p-type oxides.…”

Synthesis of Heterostructure of ZnO@MOF-46(Zn) to Improve the Photocatalytic Performance in Methylene Blue Degradation

“…Photocatalytic processes with metal-oxide-based photocatalysts have been employed in several applications, especially the degradation of various pollutants [1][2][3]. Zinc oxide (ZnO) has been widely used in numerous potential applications, including biosensors [4], light-emitting diodes (LEDs) [5], solar cells [6], gas sensors [7], and photocatalysis [8] due to its attractive properties, such as nontoxicity, chemical/thermal stability, low cost, and high mobility of electrons in the conduction band.…”

Inorganic-Diverse Nanostructured Materials for Volatile Organic Compound Sensing

“…To attain the discrimination of diverse VOCs, different 1D to 3D nanostructures (nanoparticles/quantum dots, nanocrystals, nanorods/nanowires/nanoneedles, nanofibers/nanobelts, nanotubes, nanocubes, nanocages, nanowalls, nanosheets, nanoflakes/nanoplates, nanospheres, nanoflowers, porous-nanostructures, hierarchical nanostructures, and so on) can be adapted via optimizing their selectivity and sensitivity to specific analyte [ 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 ].…”

“…Diverse nanostructures can be developed by chemical synthesis, hydrothermal, chemical vapor deposition (CVD), combustion synthesis, sputtering, electrospinning, impregnation, sol–gel, solid-state reaction, hybrid composite synthesis, etc., to achieve specific sensitivity to the target VOC [ 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 ]. However, this should be done without affecting semiconducting properties of the proposed nanostructure, otherwise the sensitivity and reproducibility may be affected significantly.…”