Temperature-Dependent n-p-n Switching and Highly Selective Room-Temperature n-SnSe₂/p-SnO/n-SnSe Heterojunction-Based...

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Air pollution necessitates efficient detection of toxic gases.
• Existing gas sensors often lack sensitivity or selectivity for pollutants like nitrogen dioxide (NO2).
• Two-dimensional (2D) materials offer potential for advanced gas sensing applications.

Purpose of the Study:

• To develop an ultrasensitive and selective gas sensor for toxic gases.
• To investigate the performance of an n-SnSe2/p-SnO/n-SnSe heterojunction for NO2 detection at room temperature.
• To elucidate the sensing mechanism of the fabricated heterojunction.

Main Methods:

• Fabrication of an n-SnSe2/p-SnO/n-SnSe heterojunction using thermal evaporation.
• Characterization of structural and morphological properties using XRD, SEM, Raman spectroscopy, XPS, and HRTEM.
• Testing the gas sensor's response, selectivity, and limit of detection (LOD) for various gases at room temperature.

Main Results:

• The heterojunction exhibited a temperature-dependent n-p-n switching behavior for NO2 detection.
• Achieved a high device response of 256% for 5 ppm NO2 at room temperature.
• Demonstrated excellent selectivity towards NO2 over other tested gases (SO2, NO, H2S, CO, H2, NH3) with a LOD of ~115 ppb.

Conclusions:

• The n-SnSe2/p-SnO/n-SnSe heterojunction is a promising material for selective NO2 gas sensing at room temperature.
• The sensing mechanism involves physisorption and charge transfer, enabling fast response and recovery.
• This work advances the application of 2D materials in developing next-generation selective gas detectors.