Electronic transport and device prospects of monolayer molybdenum disulphide grown by chemical vapour deposition

Abstract

Layered transition metal dichalcogenides display a wide range of attractive physical and chemical properties and are potentially important for various device applications. Here we report the electronic transport and device properties of monolayer molybdenum disulphide grown by chemical vapour deposition. We show that these devices have the potential to suppress short channel effects and have high critical breakdown electric field. However, our study reveals that the electronic properties of these devices are at present severely limited by the presence of a significant amount of band tail trapping states. Through capacitance and ac conductance measurements, we systematically quantify the density-of-states and response time of these states. Because of the large amount of trapped charges, the measured effective mobility also leads to a large underestimation of the true band mobility and the potential of the material. Continual engineering efforts on improving the sample quality are needed for its potential applications.

Rediscovering black phosphorus as an anisotropic layered material for optoelectronics and electronics

“…Here, we emphasize that the field-effect mobility may be strongly affected by the traps in the device and the intrinsic band mobility can be much higher than 205 cm 2 V À 1 s À 1 , as shown in MoS 2 transistors 50 . Compared with graphene transistors, the BP devices consistently show much improved current saturation behaviour as shown in Fig.…”

“…The field-effect mobility of this BP transistor is around 50 cm 2 V À 1 s À 1 , probably due to the greatly enhanced scattering by the substrate. However, we want to emphasize that this field-effect mobility may not represent the true carrier mobility because of traps and contact resistance 50 . The much improved transistor performance as compared with graphene indicates that the BP transistors can overcome the major shortcomings of graphene transistors in terms of on-off current ratio and current saturation.…”

Probing the electron states and metal-insulator transition mechanisms in molybdenum disulphide vertical heterostructures

“…M olybdenum disulphide (MoS 2 ), an n-type semiconductor [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] , shows novel properties such as superconductivity 6 , controllable valley polarization 17,18 and metal-insulator transition [3][4][5][6] (MIT). In MoS 2 field-effect transistors (FETs), gate-induced charge carriers transport in a thin layer near the surface of MoS 2 and are vulnerable to charge impurities and different types of disorder 2,3,12,14,19,20 .…”

“…In MoS 2 field-effect transistors (FETs), gate-induced charge carriers transport in a thin layer near the surface of MoS 2 and are vulnerable to charge impurities and different types of disorder 2,3,12,14,19,20 . The presence of a high-k dielectric material 3 to monolayer MoS 2 can effectively screen charge impurities and allow the observation of MIT.…”

“…However, the underlying physical mechanism and detailed MIT process need to be further clarified. Different from the studies on transport properties of MoS 2 , the capacitance spectroscopy 14 recently applied to the characterization of MoS 2 FET structures has been demonstrated as one of the most convenient and powerful method for studying the electron states in MoS 2 at room temperature. At low temperatures, however, the information obtained by this technique is limited due to the large impedance near the band edge of MoS 2 .…”