Ambipolar MoS₂ Field‐Effect Transistor by Spatially Controlled Chemical Doping

Abstract

Molybdenum disulfide (MoS2) is a widely studied 2D semiconductor, which intrinsically exhibits n‐type transport even using the high work function elemental metals as contacts. It is technically challenging to achieve ambipolar field‐effect transistors with MoS2. Herein, an effective method to prepare p‐doped MoS2 using gold chloride (AuCl3) solution is demonstrated. The doping strength can be controlled well by the process parameters. The AuCl3 doping can also be spatially selected using hexagonal‐boron nitride (h‐BN) capping masks. Subsequently, ambipolar transport can be realized in MoS2 with the coexisting parallel n‐type and p‐type channels. The resulting ambipolar MoS2 transistor presents a high room‐temperature performance, showing a high on/off ratio of 107 and a mobility of 10 s cm2 V−1 s−1 for both electron and hole.

Charge Density Depinning in Defective MoTe2 Transistor by Oxygen Intercalation

“…[ 22 ] Here, an h‐BN mask is dry‐transferred on the center of the MoTe 2 channel and leaves only the areas near palladium contacts exposed to the plasma as illustrated in the inset of Figure 1c. [ 23 ] The optical microscopic image is shown in Figure S2, Supporting Information. When the device is subjected to the plasma treatment at relatively high pressure, the exposed areas are selectively p‐doped and the in‐negligible lateral effect also leads to the oxidation of MoTe 2 beneath the metal contacts.…”

Self-Terminated Surface Monolayer Oxidation Induced Robust Degenerate Doping in MoTe2 for Low Contact Resistance

“…More importantly, with the degenerately doped MoTe 2 , we demonstrate a record low contact resistance of 0.6 kΩ μm for MoTe 2 . In the future, this method can be utilized to make high-performance MoTe 2 FETs or tunnel FETs, where the degenerately doped MoTe 2 contacts can be spatially selected by using the h-BN masking technique …”

“…More importantly, with the degenerately doped MoTe 2 , we demonstrate a record low contact resistance of 0.6 kΩ μm for MoTe 2 . In the future, this method can be utilized to make high-performance MoTe 2 FETs or tunnel FETs, where the degenerately doped MoTe 2 contacts can be spatially selected by using the h-BN masking technique 31. The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsami.0c03762.XPS spectra before and after O 2 plasma treatment with varied durations, evolutions of the wave number and intensity of Raman E 2g 1 peak with respect to plasma treatment durations, evolution of field-effect hole mobility with respect to plasma treatment durations, and output curves of a pristine transistor and a p-type MoTe 2 transistor (PDF) School of Physics and Electronics, Central South University, Changsha 410083, China; orcid.org/0000-0002-7992-8092; Email: jian.sun@csu.edu.cn Won Jong Yoo − SKKU Advanced Institute of Nano-…”

Synthesis of Large-Area Crystalline MoS2 by Sputter Deposition and Pulsed Laser Annealing

“…In relation to MoS 2 , ambipolarity has been reported in mostly flakes, heterostructures, or CVD-grown monolayer devices . It has also been noted in several studies on liquid-gated MoS 2 devices using flakes. , Ambipolarity can be promoted by applying specific process steps such as an oxygen plasma treatment, catalytic oxidation, indium edge contacts, or chemical doping . Furthermore, the choice of substrate is significant, related to enhancing or eliminating FLP, as well as the choice of MoS 2 thickness .…”