Bipolar junction transistors (BJTs), the basic building blocks of integrated circuits, are deployed to control switching applications and logic operations. However, as the thickness of a conventional BJT device approaches a few atoms, its performance decreases substantially. The stacking of atomically thin 2D semiconductor materials is advantageous for manufacturing atomically thin BJT devices owing to the high carrier density of electrons and holes. Here, an atomically thin n-p-n BJT device composed of heavily doped molybdenum ditelluride (n-MoTe 2 ) and germanium selenide (p-GeSe) sheets stacked over each other by van der Waals interactions is reported. In a common-emitter configuration, MoTe 2 /GeSe/MoTe 2 BJT devices exhibit a considerably high current gain (β = I c /I b = 29.3) at V be = 2.5 V. The MoTe 2 / GeSe/MoTe 2 BJT device is employed to detect streptavidin biomolecules as analytes within <10 s. The real-time response of the functionalized BJT device is examined at various concentrations of streptavidin biomolecules ranging from 250 to 5 pm. Such vdW BJT devices can trigger the development of state-of-the-art electronic devices that can be used as biosensors to detect the various kinds of target DNA and proteins like spike protein of Covid-19.
There have been a few studies of
heterojunctions composed of two-dimensional
transition-metal dichalcogenides (TMDs) and an oxide layer, but such
studies of high-performance electric and optoelectronic devices are
essential. Such heterojunctions with low-resistivity metal contacts
are needed by the electronics industry to fabricate efficient diodes
and photovoltaic devices. Here, a van der Waals heterojunction composed
of p-type black phosphorus (p-BP) and n-type indium–gallium–zinc
oxide (n-IGZO) films with low-resistivity metal contacts is reported,
and it demonstrates high rectification. The low off-state leakage
current in the thick IGZO film accounts for the high rectification
ratio in a sharp interface of p-BP/n-IGZO devices. For electrostatic
gate control, an ionic liquid is introduced to achieve a high rectification
ratio of 9.1 × 104. The photovoltaic measurements
of p-BP/n-IGZO show fast rise and decay times, significant open-circuit
voltage and short-circuit current, and a high photoresponsivity of
418 mA/W with a substantial external quantum efficiency of 12.1%.
The electric and optoelectronic characteristics of TMDs/oxide layer
van der Waals heterojunctions are attractive for industrial applications
in the near future.
We used Pb as an intercalated layer between the graphene and Au and measured the spin–orbit interaction in local and non-local measurement configurations.
Tuning of the Fermi level in transition metal dichalcogenides (TMDCs) leads to devices with excellent electrical and optical properties. In this study, we controlled the Fermi level of MoTe2 by...
The electrical and optical properties of transition metal dichalcogenides (TMDs) can be effectively modulated by tuning their Fermi levels. To develop a carrier-selectable optoelectronic device, we investigated intrinsically p-type MoTe2, which can be changed to n-type by charging a hexagonal boron nitride (h-BN) substrate through the application of a writing voltage using a metal gate under deep ultraviolet light. The n-type part of MoTe2 can be obtained locally using the metal gate pattern, whereas the other parts remain p-type. Furthermore, we can control the transition rate to n-type by applying a different writing voltage (i.e., − 2 to − 10 V), where the n-type characteristics become saturated beyond a certain writing voltage. Thus, MoTe2 was electrostatically doped by a charged h-BN substrate, and it was found that a thicker h-BN substrate was more efficiently photocharged than a thinner one. We also fabricated a p–n diode using a 0.8 nm-thick MoTe2 flake on a 167 nm-thick h-BN substrate, which showed a high rectification ratio of ~ 10−4. Our observations pave the way for expanding the application of TMD-based FETs to diode rectification devices, along with optoelectronic applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.