Coexistence of Negative and Positive Photoconductivity in Few‐Layer PtSe₂ Field‐Effect Transistors

Abstract

Platinum diselenide (PtSe 2 ) field-effect transistors with ultrathin channel regions exhibit p-type electrical conductivity that is sensitive to temperature and environmental pressure. Exposure to a supercontinuum white light source reveals that positive and negative photoconductivity coexists in the same device. The dominance of one type of photoconductivity over the other is controlled by environmental pressure. Indeed, positive photoconductivity observed in high vacuum converts to negative photoconductivity when the pressure is raised. Density functional theory calculations confirm that physisorbed oxygen molecules on the PtSe 2 surface act as acceptors. The desorption of oxygen molecules from the surface, caused by light irradiation, leads to decreased carrier concentration in the channel conductivity. The understanding of the charge transfer occurring between the physisorbed oxygen molecules and the PtSe 2 film provides an effective route for modulating the density of carriers and the optical properties of the material.

Electric Transport in Few-Layer ReSe2 Transistors Modulated by Air Pressure and Light

“…The decrease in the current under light is enhanced at = 30 V. Illumination normally generates additional carriers in a semiconductor material, which increase its conductivity. Conversely, negative photoconductivity has been reported in a few 1D and 2D materials, and explained as a photogating effect due to trap centers, light-induced desorption of surface gas molecules or surface plasmons [ 43 , 44 , 45 , 46 , 47 ]. The origin and role of the negative photoconductivity in low-dimensional materials is still poorly understood.…”

High-performance hierarchical O-SnS/I-ZnIn2S4 photodetectors by leveraging the synergy of optical regulation and band tailoring

“…channel limit, thickness/strain regulated physical attributes, flexible integratability, etc. Thus far, hundreds of 2DLMs spanning graphene, 7 transition metal dichalcogenides, [8][9][10] nitrides, 11 phosphides, 12 oxyhalides, 13 and Mxenes 14 have been developed for photodetection applications.…”

“…Since the revolutionary preparation of one-atom-thick graphene, 2D layered materials (2DLMs) have been established as one of the most promising material platforms toward realizing the next-generation integrated electronics, photonics and optoelectronics, 1–6 by virtue of the intriguing attributes spanning high light transmittance, excellent flexibility, wide-range properties, remarkable quantum confinement, ultra-scaled channel limit, thickness/strain regulated physical attributes, flexible integratability, etc. Thus far, hundreds of 2DLMs spanning graphene, 7 transition metal dichalcogenides, 8–10 nitrides, 11 phosphides, 12 oxyhalides, 13 and Mxenes 14 have been developed for photodetection applications.…”

Fast and recoverable NO2 detection achieved by assembling ZnO on Ti3C2Tx MXene nanosheets under UV illumination at room temperature

“…The UV light-induced gas desorption could help to accelerate the recovery process of the Ti 3 C 2 T x –ZnO NS gas sensor. 70 In addition, comparison of the NO 2 sensing performances of the various gas sensors under UV illumination, including response/recovery time and sensitivity, are illustrated in Table S1 †. The Ti 3 C 2 T x –ZnO NS sensor exhibited better response and recovery properties compared with other reported NO 2 sensors.…”