Self-Assembled SnO₂/SnSe₂ Heterostructures: A Suitable Platform for Ultrasensitive NO₂ and H₂ Sensing

Abstract

The successful growth of high-quality SnSe 2 crystals by chemical vapour transport (CVT) and epitaxial films by molecular beam epitaxy (MBE) was reported by several groups 1-2 . However, the productivity by CVT and MBE is far below than that by the Bridgman technique. Compared with the high cost of equipment of MBE, both CVT and Bridgman methods are relatively faster and more economic. However, the CVT growth would introduce a trace of transport agent, with an obvious influence on the carrier density for semiconductor, and would also produce chalcogen vacancies at high temperature. For the CVT-grown SnSe 2 crystal, the suppression of Se vacancies can be achieved by adding excess Se and lowering the temperature gradient. The Se vacancies can be controlled by turning the source beam flux ratio in the MBE growth, while the lattice-matched substrate must be carefully chosen. Therefore, we can conclude the Bridgman growth is the most suitable method for up scaling for the case of SnSe 2 .

Chemical reactions on surfaces for applications in catalysis, gas sensing, adsorption-assisted desalination and Li-ion batteries: opportunities and challenges for surface science

“…The formed SnO 2 skin is amorphous, as indicated by the disappearance of diffraction peaks in the low-energy electron diffraction pattern. 154 Density functional theory results indicate that SnO 2 /SnSe 2 is more sensitive to chemisorbed species with respect to the pristine SnSe 2 . 154 As a matter of fact, H 2 O, NO 2 and H 2 adsorption yield no substantial effect on both the electronic structure and charge densities (Fig.…”

“…154 Density functional theory results indicate that SnO 2 /SnSe 2 is more sensitive to chemisorbed species with respect to the pristine SnSe 2 . 154 As a matter of fact, H 2 O, NO 2 and H 2 adsorption yield no substantial effect on both the electronic structure and charge densities (Fig. 5) of pristine SnSe 2 , which turns out to be unsuitable for gas sensing applications.…”

“…Here, we focus on the case-study example of tin diselenide (SnSe 2 ), a van der Waals semiconductor with high electron mobility (462.6 cm 2 V À1 s À1 at T = 300 K 148 ), which has been recently reported to be a suitable material for the detection of NO 2 149,150 and NH 3 , 151,152 in a nitrogen background carrier gas, as well as CH 4 153 and humidity in dry air. 151,152 The presence of Se vacancies triggers oxidation of the surface in oxidative environments (including air), with the emergence of a SnO 2 surface layer, with sub-nanometric thickness, 154 whose presence is evident in HREELS analysis (Fig. 4).…”

Monitoring the Covid-19 Diffusion by Combining Wearable Biosensors and Smartphones.

“…Besides, it can record the progress of patient symptoms and monitor them at home while in quarantine. The proposed system is only a preliminary prototype, and its performance can be strongly improved by using innovative two-dimensional semiconductors with higher charge carrier mobility as reported in the related literature [16][17][18][19][20][21][22][23][24][25].…”

“…Later, the Chinese Government and the World Health Organization (WHO) recognized a novel coronavirus (COVID-19) belongs to the same virus family of the Severe Acute Respiratory Syndrome (SARS) that outbroke in 2002-2003 [2]. After a rapid spread and exceeding the total number of cases across the world compared to SARS cases, the SARS-COV-19 (COVID- 19) was declared a pandemic by the World Health Organization (WHO) on March 11, 2020 [3]. The COVID-19 is a respiratory disease which means that it primarily injures the vascular endothelium.…”