Exceptionally Uniform and Scalable Multilayer MoS₂ Phototransistor Array Based on Large-Scale MoS₂ Grown by RF Sputtering, Electron Beam Irradiation, and Sulfurization

Abstract

Two-dimensional molybdenum disulfide (MoS2) has emerged as a promising material for optoelectronic applications because of its superior electrical and optical properties. However, the difficulty in synthesizing large-scale MoS2 films has been recognized as a bottleneck in uniform and reproducible device fabrication and performance. Here, we proposed a radio-frequency magnetron sputter system, and post-treatments of electron beam irradiation and sulfurization to obtain large-scale continuous and high-quality multilayer MoS2 films. Large-area uniformity was confirmed by no deviation of electrical performance in fabricated MoS2 thin-film transistors (TFTs) with an average on/off ratio of 103 and a transconductance of 0.67 nS. Especially, the photoresponsivity of our MoS2 TFT reached 3.7 A W–1, which is a dramatic improvement over that of a previously reported multilayer MoS2 TFT (0.1 A W–1) because of the photogating effect induced by the formation of trap states in the band gap. Finally, we organized a 4 × 4 MoS2 phototransistor array with high photosensitivity, linearity, and uniformity for light detection, which demonstrates the great potential of 2D MoS2 for future-oriented optoelectronic devices.

Highly sensitive active pixel image sensor array driven by large-area bilayer MoS2 transistor circuitry

“…The main mechanism for the high R ph of the bilayer MoS 2 phototransistor is PG effect by the holes trapped at subgap states 33 , 52 – 55 . The TEM and XPS analysis in Fig.…”

“…3b , the morphology of the MoS 2 film appears smooth and consists of several grains. The corresponding fast Fourier transform pattern shows numerous spots forming halo rings, indicating that the MoS 2 film has several random crystallite orientations 33 . According to Supplementary Fig.…”

“…8b–d show the I ph – P inc curves of the device under RGB light illumination, respectively 53 . By sweeping the gate voltage ( V gs ) from −40 to 40 V, the slope of I ph – P inc (i.e., α : absorption coefficient) decreases, indicating that the dominant mechanism for R ph high switches from photoconductive (PC) effect to PG effect 33 , 54 . PC effect is that the conductivity of the channel is increased by the photogenerated electron–hole pairs, whereas PG effect is one of special PC effect resulted from accumulation of holes and conduction band lowering due to the defects, impurities, or multi-junction structure of channel materials.…”

Activating the Basal Plane of 2H-MoS2 by Doping Phosphor for Enhancement in the Photocatalytic Degradation of Organic Contaminants

“…However, thermodynamics favors the existence of stabilized basal planes and hinders the formation of unsaturated electrons and highly energetic oxidizing agents under coordinated edge sites, obstructing the activating of inert base planes. Hence, extensive efforts have been devoted to actively maximize the unutilized base planes of 2H-MoS 2 , which is mainly adopted in the methods of developing defect-rich MoS 2 structures , and doping other atoms (Zn, Co, etc. , ). Technically, substituting S atoms with other atoms is anticipated to be exercisable versus the complexity of introducing defects.…”

Active-matrix monolithic gas sensor array based on MoS2 thin-film transistors

“…However, poor reproducibility and uniformity of exfoliated MoS 2 flakes significantly limit their practical applications. In this regard, massive efforts to grow large-area and high-crystalline MoS 2 films have been devoted, and a feasibility of diverse growth methods has been demonstrated, including chemical vapor deposition (CVD) 33,34 , atomic layer deposition (ALD) 35,36 , and physical vapor deposition (PVD) 37,38 . Nonetheless, the poor reliability and reproducibility of CVD owing to the unstable gas flow dynamic in the chamber as well as high-cost and low throughput of ALD reduce the availability of rather efficient and scalable growth techniques.…”