Fabrication and characterization of a ZnO quantum dots-based metal–semiconductor–metal sensor for hydrogen gas

Abstract

This paper reports an interdigitated metal-semiconductor-metal (MSM) based hydrogen gas (H 2 ) sensor using colloidal zinc oxide (ZnO) quantum dots (QDs) as the sensing material. The active layer is obtained by spin coating of as-synthesized colloidal ZnO QDs on a SiO 2 /Si substrate in which the SiO 2 layer is grown by oxidation of the Si substrate. The surface morphology of a ZnO QDs -based active film is measured using scanning electron microscopy (SEM) and atomic force microscopy (AFM) support for enhanced gas response. The change in current is measured for different concentrations of H 2 gas at 175 °C in an ambient air atmosphere. Reasonably good gas responses of ∼41% for 1% H 2 gas and 83.2% for 4% H 2 gas have been obtained in ambient air condition. A high selectivity of the proposed sensor with respect to ammonia, sulfur dioxide and organic vapours such as acetone, methanol, chlorobenzene, and chloroform has also been achieved due to nanostructure ZnO films.

Room temperature high hydrogen gas response in Pd/TiO 2 /Si/Al capacitive sensor

“…The capacitance versus voltage ( C – V ) and conductance versus voltage (G–V) characteristics for the fabricated MOS sensor are measured at a frequency of 1 MHz. The gas sensing is performed inside a homemade self‐design gas sensing chamber of volume 10 litre with inlet–outlet facilities, reported in [7, 23]. The change in the capacitance and the conductance for different concentrations of H 2 is shown in Figs.…”

“…When H 2 gas is exposed to the as‐fabricated MOS sensor, first, H 2 molecules are separated on Pd metal surface due to its catalytic behaviour. Some of H 2 atom diffuse through Pd dot and at TiO 2 surface these atoms polarised and made a dipole layer which is responsible for changes in the work function of Pd and this modification in work function is responsible for changes in the flat‐band voltage of the fabricated device [7, 8, 21]. There is a chemical bond between Pd surface and chemisorbed oxygen anions on Pd surface, which affects the work function of Pd.…”

“…Various types of hydrogen gas sensors have been reported in the literature [5, 7–9]. Most of the gas sensors use transition metal oxides as active sensing material in the device [4, 7, 10].…”

“…Various types of hydrogen gas sensors have been reported in the literature [5, 7–9]. Most of the gas sensors use transition metal oxides as active sensing material in the device [4, 7, 10]. Among various device structures, metal‐oxide semiconductor (MOS)‐based capacitive gas sensors have drawn considerable attention of the researchers for H 2 gas sensing applications due to their simple device structure and possibility of enhancing the gas sensing properties by changing the work function of electrode‐metal and oxide material [11, 12] of the capacitor.…”

Atomic layer–deposited nanostructures and their applications in energy storage and sensing

“…In ALD-related researches, a wide range of materials and structures such as various wafers [27], nanoparticles [28], nanowires [29], nanotube [30], soft materials [31], and biological materials [32], can be served as substrates for ALD coating. The resultant nanostructures are applied for enhanced performance in batteries [33,34], supercapacitors [35,36,37], catalysts [38,39,40], and sensor areas [41,42].…”