ReS₂ Nanosheet-Based Channels for Two-Dimensional Field Effect Transistors and Phototransistors with High Photoresponsivity

Abstract

Compared to traditional bulk materials, two-dimensional transition metal dichalcogenides (2D TMDCs) hold the potential in low power logic, photoelectric, and nonvolatile memory devices due to a tunable band structure, pure heterojunction interface, and photodetection for a wide spectral range. ReS 2 is chosen as the channel material in our work because it possesses excellent photoresponsivity. In addition, a BN dielectric is inserted between SiO 2 and ReS 2 as a gate dielectric. The pure heterojunction interface at BN/ReS 2 enhances the electric characteristics, including negligible hysteresis window and higher mobility. The photoelectric measurement results show that ReS 2 devices with or without the BN dielectric have an outstanding photoresponsivity of up to ∼10 6 A/W and a specific detectivity of up to ∼10 13 Jones as well as a fast photoresponse time of less than 100 ms under an extremely low optical power density of 0.47 μW/cm 2 , which fully proves that ReS 2 has the ability to detect very weak light. Also, the contact resistance and Schottky barrier height are also extracted with variable temperature measurements for the ReS 2 device. The higher contact resistance and unsymmetric output currents illustrate that the mirror force is the main factor leading to the reduction of the Schottky barrier height. Finally, the influences of the ReS 2 channel thickness on mobility and photoresponsivity are also studied by the device-to-device variability. The work in this paper further demonstrates that nanosheet-based ReS 2 can be regarded as an excellent candidate for application into the field of light-sensitive sensors under the condition of the CMOS-compatible process.

ReS2/WSe2 Type II Heterojunction Phototransitors with Integrated van der Waals Electrodes to Achieve Ultralow Dark Current and Fast Response Time

“…The few-layer WSe 2 transistor exhibits an obvious ambipolar characteristic with an off-state around the gate-source bias ( V GS ) of −5 V. The transfer curves of the ReS 2 transistor in Figure b indicate an obvious n-type characteristic and a high current on/off ratio (>10 7 ). In addition, the calculated maximal mobilities were 11.700 and 23.283 cm 2 V –1 s –1 for the ReS 2 and WSe 2 transistors, respectively, according to μ = (Δ I DS /Δ V GS )­( L / WC ox V DS ) at V DS of 1 V, where L , W , and C ox are the channel length, channel width, and gate dielectric capacitance, respectively, in agreement with previous reports. − Parts a and b of Figure S2 show the output characteristics of few-layer WSe 2 and ReS 2 transistors at different gate voltages. Also, the output currents of both the WSe 2 and ReS 2 transistors linearly increase with the drain voltage, which illustrates that the source and drain electrodes are excellent ohmic contacts for these two devices.…”

Temperature-Dependent Conduction and Photoresponse in Few-Layer ReS2

“…Such a high SS might indicate a high density of defects at the interface with SiO 2 , which are also the main cause of the hysteresis. The quality of the interface with the gate dielectric can be improved through the introduction of an ultrathin BN dielectric, which results in higher electrical performances of the device . The field-effect mobility of ∼3 cm 2 V –1 s –1 was extracted from the linear part of the transfer curve on the linear scale, shown in the inset of Figure b, according to the formula where C ox = 1.15 × 10 –8 F cm –2 is the gate dielectric capacitance.…”

“…The quality of the interface with the gate dielectric can be improved through the introduction of an ultrathin BN dielectric, which results in higher electrical performances of the device. 32 The field-effect mobility of ∼3 cm 2 V −1 s −1 was extracted from the linear part of the transfer curve on the linear scale, shown in the inset of Figure 2b, according to the formula where C ox = 1.15 × 10 −8 F cm −2 is the gate dielectric capacitance. The result is consistent with other works on similar devices 18,19 and is typical of several TMDs.…”

2D Rhenium Dichalcogenides: From Fundamental Properties to Recent Advances in Photodetector Technology

“…Here, h-BN as a dielectric provides the 2D material channel with negligible drain current hysteresis and higher mobility. [307,315] This suggests that by choosing a low resistance metallization and encapsulating the ReSe 2 with h-BN layers on either side, FETs with improved performance can be achieved. Calculated field-effect mobility (166 cm 2 / Vs at 200 K) and current ON/OFF ratio (≈10 7 ) values obtained from such a device, are among the highest values reported.…”