MoS₂ Van der Waals p–n Junctions Enabling Highly Selective Room‐Temperature NO₂ Sensor

Abstract

Van der Waals p-n junctions of 2D materials present great potential for electronic devices due to the fascinating properties at the junction interface. In this work, an efficient gas sensor based on planar 2D van der Waals junctions is reported by stacking n-type and p-type atomically thin MoS 2 films, which are synthesized by chemical vapor deposition (CVD) and soft-chemistry route, respectively. The electrical conductivity of the van der Waals p-n junctions is found to be strongly affected by the exposure to NO 2 at room temperature (RT). The MoS 2 p-n junction sensor exhibits an outstanding sensitivity and selectivity to NO 2 at RT, which are unavailable in sensors based on individual n-type or p-type MoS 2 . The sensitivity of 20 ppm NO 2 is improved by 60 times compared to a p-type MoS 2 sensor, and an extremely low limit of detection of 8 ppb is obtained under ultraviolet irradiation. Complete and very fast sensor recovery is achieved within 30 s. These results are superior to most of the previous reports related to NO 2 detection. This work establishes an entirely new sensing platform and proves the feasibility of using such materials for the high-performance detection of gaseous molecules at RT.

Mechanical testing of two-dimensional materials: a brief review

“…MoS 2 is one of the most extensively studied TMDs [56,60,64,65,[151][152][153][154], which has a hexagonal structure consisted of Mo and S atoms at alternating corners. The driving force to integrate MoS 2 into MEMS/NEMS is that, unlike graphene, it has an indirect bandgap of 1.29 eV [62].…”

“…Layered TMDs consist of tiers of hexagonal lattices that are governed by the transition metal-chalcogen interaction. Molybdenum disulfide (MoS 2 ) is one of the most intensively studied TMDs [54][55][56][57][58][59][60][61] in which a layer of hexagonal Mo atoms is sandwiched by two layers of hexagonal S atoms. The driving force to integrate MoS 2 into MEMS/NEMS is that, unlike graphene, monolayer MoS 2 has a direct bandgap of 1.9 eV, which is important for semiconductor applications [62].…”

Light-activated gas sensing: a perspective of integration with micro-LEDs and plasmonic nanoparticles

“…Their working principles are based on resistance change upon adsorption and desorption of target gas molecules on the surface of semiconductors. The chemoresistive gas sensors usually utilize various semiconducting materials including metal oxides [14][15][16][17][18][19][20][21][22] , 2dimensional (2D) materials [23][24][25][26][27][28][29][30] , or conductive polymers [31][32][33] . Although each material has been reported for its superior gas sensing characteristics to specific target gas molecules through various strategies, the common challenges exist, which is the high operating temperature.…”

Enhanced positive humidity sensitive behavior of p-reduced graphene oxide decorated with n-WS2 nanoparticles

“…Moreover, inspired by the outstanding performance of heterojunction composite materials in gas sensors [25,26], it is a good strategy to further improve the positive humidity sensing properties of rGO by constructing heterojunction. In recent years, the transition metal dichalcogenides (TMDCs) have received considerable attention due to their unique electronic properties [27][28][29][30].…”