Unraveling the Mechanism of the 150-Fold Photocurrent Enhancement in Plasma-Treated 2D TMDs

Abstract

Two-dimensional (2D) transition metal dichalcogenides (TMDs) are increasingly investigated for applications such as optoelectronic memories, artificial neurons, sensors, and others that require storing photogenerated signals for an extended period. In this work, we report an environment-and gate voltage-dependent photocurrent modulation method of TMD monolayer-based devices (WS 2 and MoS 2 ). To achieve this, we introduce structural defects using mild argon−oxygen plasma treatment. The treatment leads to an extraordinary over 150-fold enhancement of the photocurrent in vacuum along with an increase in the relaxation time. A significant environmental and electrostatic dependence of the photocurrent signal is observed. We claim that the effect is a combined result of atomic vacancy introduction and oxide formation, strengthened by optimal wavelength choice for the modified surface. We believe that this work contributes to paving the way for tunable 2D TMD optoelectronic applications.

Emerging Frontiers of 2D Transition Metal Dichalcogenides in Photovoltaics Solar Cell

“…In a recent investigation, the researchers employed a mild argon‐oxygen plasma treatment on WS 2 and MoS 2 monolayer devices, resulting in a more than 150‐fold increase in photocurrent in a vacuum. [ 88 ] The tuning effect was achieved through plasma exposure, leading to the formation of various structures such as sulfur vacancies, nonstoichiometric transition metal oxide (TMO), and stoichiometric TMO on the samples. Sulfur vacancies and TMD‐TMO heterojunctions induced charge trapping, and effective electron‐hole pairs could be generated on the junctions by selecting the appropriate light wavelength for irradiation.…”

“…For metal-semiconductor contacts, aligning the energy bands of plasma-treated semiconductors with the metal energy band structure leads to a transition from Schottky to ohmic contacts, effectively reducing contact resistance. Conventional plasma treatments involve organic molecules, metal particles, various gases (O 2 , [86][87][88] N 2 , [89][90][91] Ar, [92][93][94] etc. ), and more.…”

2D Materials in Flexible Electronics: Recent Advances and Future Prospectives

“…More specifically, photo-sensors are the elementary unit of any imaging system which mainly absorbs the incident light and converts it to the electrical signals in the form of photocurrent or photovoltage. Several physical phenomena such as photoconduction, − photogating, − persistent photocurrent, ,− avalanche photodetection, − photovoltaics, ,− photo-thermal effect, − and photo-bolometric effect − can occur to generate the electric charge in a photo-sensing device. Depending upon the specific characteristics of the used 2D material, the suitable physical mechanisms for the electric charge generation can be exploited to develop the flexible PD device.…”

Metal (Au, Ag, Pt) Doping Effects on the Gas-Sensing Mechanism and Characteristics of Two-Dimensional WS2: A First-Principle

“…Two-dimensional transition metal dichalcogenides (TMDs) have garnered significant attention due to their graphene-like layered structure. − This endows them with outstanding electrical, chemical, mechanical, and optical properties. Consequently, 2D TMDs are widely regarded as having enormous potential for applications in the sensor field.…”