2 research outputs found
Light-Tunable Polarity and Erasable Physisorption-Induced Memory Effect in Vertically Stacked InSe/SnS<sub>2</sub> Self-Powered Photodetector
van der Waals heterojunctions with tunable polarity are
being actively
explored for more Moore and more-than-Moore device applications, as
they can greatly simplify circuit design. However, inadequate control
over the multifunctional operational states is still a challenge in
their development. Here, we show that a vertically stacked InSe/SnS2 van der Waals heterojunction exhibits type-II band alignment,
and its polarity can be tuned by an external electric field and by
the wavelength and intensity of an illuminated light source. Moreover,
such SnS2/InSe diodes are self-powered broadband photodetectors
with good performance. The self-powered performance can be further
enhanced significantly with gas adsorption, and the device can be
quickly restored to the state before gas injection using a gate voltage
pulse. Our results suggest a way to achieve and design multiple functions
in a single device with multifield coupling of light, electrical field,
gas, or other external stimulants
Enhanced NO<sub>2</sub> Sensitivity of Vertically Stacked van der Waals Heterostructure Gas Sensor and Its Remarkable Electric and Mechanical Tunability
Nanodevices based on van der Waals heterostructures have
been predicted,
and shown, to have unprecedented operational principles and functionalities
that hold promise for highly sensitive and selective gas sensors with
rapid response times and minimal power consumption. In this study,
we fabricated gas sensors based on vertical MoS2/WS2 van der Waals heterostructures and investigated their gas
sensing capabilities. Compared with individual MoS2 or
WS2 gas sensors, the MoS2/WS2 van
der Waals heterostructure gas sensors are shown to have enhanced sensitivity,
faster response times, rapid recovery, and a notable selectivity,
especially toward NO2. In combination with a theoretical
model, we show that it is important to take into account created trapped
states (flat bands) induced by the adsorption of gas molecules, which
capture charges and alter the inherent built-in potential of van der
Waals heterostructure gas sensors. Additionally, we note that the
performance of these MoS2/WS2 heterostructure
gas sensors could be further enhanced using electrical gating and
mechanical strain. Our findings highlight the importance of understanding
the effects of altered built-in potentials arising from gas molecule
adsorption induced flat bands, thus offering a way to enhance the
gas sensing performance of van der Waals heterostructure gas sensors