Air-Stable n-Doping of WSe₂ by Anion Vacancy Formation with Mild Plasma Treatment

Abstract

Transition metal dichalcogenides (TMDCs) have been extensively explored for applications in electronic and optoelectronic devices due to their unique material properties. However, the presence of large contact resistances is still a fundamental challenge in the field. In this work, we study defect engineering by using a mild plasma treatment (He or H2) as an approach to reduce the contact resistance to WSe2. Material characterization by X-ray photoelectron spectroscopy, photoluminescence, and Kelvin probe force microscopy confirm defect-induced n-doping, up to degenerate level, which is attributed to the creation of anion (Se) vacancies. The plasma treatment is adopted in the fabrication process flow of WSe2 n-type metal-oxide-semiconductor field-effect transistors to selectively create anion vacancies at the metal contact regions. Due to lowering the metal contact resistance, improvements in the device performance metrics such as a 20× improvement in ON current and a nearly ideal subthreshold swing value of 66 mV/dec are observed. This work demonstrates that defect engineering at the contact regions can be utilized as a reliable scheme to realize high-performance electronic and optoelectronic TMDC devices.

Hole Conduction of Tungsten Diselenide Crystalline Transistors by Niobium Dopant

“…There was no difference in peak position or broadening for the flakes with and without Nb impurity. Nevertheless, similar doping mechanisms for n-doping (upshifts of the peaks) of WSe 2 have been reported using mild plasma treatment [6] and potassium exposure. [3b,12] The onset of B 2g 1 vibration at 2L appeared near 314.9 cm −1 , as theoretically predicted by Ding et al [12c] The chemical species and impact of Nb dopant in the material were analyzed by XPS.…”

Sulfur vacancy-induced reversible doping of transition metal disulfides via hydrazine treatment

“…27,28 Similar behaviour was found in WSe2, where hydrogen plasma treatment was Please do not adjust margins Please do not adjust margins employed to generate selenium vacancies, which reduces the contact resistance and improves the mobility. 29 But, with longer doping time, the field-effect mobility slightly decreases. This reduction in mobility could be due to an increase in scattering probability of mobile carriers in the channel.…”

Controllable P‐ and N‐Type Conversion of MoTe2 via Oxide Interfacial Layer for Logic Circuits

“…Because 2D‐TMDC materials have atomic‐scale thickness, it is difficult to modulate the p‐ and n‐type characteristics by employing the conventional technique of controlling electron/hole concentrations via ion implantation, unlike in bulk silicon, as ion bombardment can impart serious lattice damage in 2D‐TMDC materials. In this regard, few attempts have been made to tune the doping type in 2D‐TMDC materials by adopting other nonconventional approaches, such as chemical doping using dichloroethane, benzyl viologen (BV), and AuCl 3 ; and plasma‐induced doping . However, the practical implementation of these techniques has been very limited, mainly because of the chemical instability and processing complexity.…”