Reduced dopant-induced scattering in remote charge-transfer-doped MoS ₂ field-effect transistors

Abstract

Efficient doping for modulating electrical properties of two-dimensional (2D) transition metal dichalcogenide (TMDC) semiconductors is essential for meeting the versatile requirements for future electronic and optoelectronic devices. Because doping of semiconductors, including TMDCs, typically involves generation of charged dopants that hinder charge transport, tackling Coulomb scattering induced by the externally introduced dopants remains a key challenge in achieving ultrahigh mobility 2D semiconductor systems. In this study, we demonstrated remote charge transfer doping by simply inserting a hexagonal boron nitride layer between MoS 2 and solution-deposited n-type dopants, benzyl viologen. A quantitative analysis of temperature-dependent charge transport in remotely doped devices supports an effective suppression of the dopant-induced scattering relative to the conventional direct doping method. Our mechanistic investigation of the remote doping method promotes the charge transfer strategy as a promising method for material-level tailoring of electrical and optoelectronic devices based on TMDCs.

High-Performance Two-Dimensional Electronics with a Noncontact Remote Doping Method

“…At room temperature, the mobility of the RD device (52 cm 2 V −1 s −1 ) was higher than that of the DD device (33 cm 2 V −1 s −1 ). 36 In general, optical phonon scattering is weaker at lower temperatures. Therefore, the channel mobility is higher (μ ∝ T −γ , where γ is the temperature-dependent power factor 35 ) when carrier transport is dominated by phonon scattering than when carrier transport is dominated by charge impurity scattering.…”

Unusual Selective Monitoring of N,N-Dimethylformamide in a Two-Dimensional Material Field-Effect Transistor

“…To evaluate the doping ability in more detail, we extracted the change in the carrier density of MoS 2 from the transfer characteristics of 19 devices (Figure a and Figure S3). The amount of carriers injected into MoS 2 , Δ n , can be determined using eq normalΔ italicn = C ox normalΔ V th / q where Δ V th is the change in threshold voltage, C ox is the capacitance of the oxide film, and q is the elementary charge.…”

Challenges for Nanoscale CMOS Logic Based on Two-Dimensional Materials

“…This problem can be addressed with the concept of modulation doping, where the charge dopants are spatially separated from the conduction channel. Recently, this concept of remote modulation doping for 2D TMD channels has been theoretically proposed [ 98 ] and experimentally demonstrated [ 99 , 100 ]. In these works, a MoS channel is separated from the molecular dopants using a few layers of hBN as a tunnel barrier, effectively suppressing charged impurity scattering and achieving a sizable mobility enhancement [ 99 ].…”