Stable, highly-responsive and broadband photodetection based on large-area multilayered WS₂ films grown by pulsed-laser deposition

Abstract

The progress in the field of graphene has aroused a renaissance of keen research interest in layered transition metal dichalcogenides (TMDs). Tungsten disulfide (WS2), a typical TMD with favorable semiconducting band gap and strong light-matter interaction, exhibits great potential for highly-responsive photodetection. However, WS2-based photodetection is currently unsatisfactory due to the low optical absorption (2%-10%) and poor carrier mobility (0.01-0.91 cm(2) V(-1) s(-1)) of the thin WS2 layers grown by chemical vapor deposition (CVD). Here, we introduce pulsed-laser deposition (PLD) to prepare multilayered WS2 films. Large-area WS2 films of the magnitude of cm(2) are achieved. Comparative measurements of a WS2-based photoresistor demonstrate its stable broadband photoresponse from 370 to 1064 nm, the broadest range demonstrated in WS2 photodetectors. Benefiting from the large optical absorbance (40%-85%) and high carrier mobility (31 cm(2) V(-1) s(-1)), the responsivity of the device approaches a high value of 0.51 A W(-1) in an ambient environment. Such a performance far surpasses the CVD-grown WS2-based photodetectors (μA W(-1)). In a vacuum environment, the responsivity is further enhanced to 0.70 A W(-1) along with an external quantum efficiency of 137% and a photodetectivity of 2.7 × 10(9) cm Hz(1/2) W(-1). These findings stress that the PLD-grown WS2 film may constitute a new paradigm for the next-generation stable, broadband and highly-responsive photodetectors.

An Innovative Postdeposition Annealing Approach Producing Centimeter‐Scale In2O3/In2(TeO3)3 Bulk Heterojunction Thin Film for Room‐Temperature Persistent Photoconductivity

“…In this contribution, as is schematically shown in Figure 1a,b, we exploited pulsed-laser deposition (PLD), an efficient, versatile, and large-scale deposition approach, [28][29][30][31][32][33][34][35][36][37] for the production of centimeter-scale In 2 Te 3 thin films, followed by a postdeposition annealing treatment in ambient environment. For the first time, we achieved the centimeter-scale inorganic bulk heterojunction thin film, hybrid In 2 O 3 /In 2 (TeO 3 ) 3 system.…”

Large area few-layer TMD film growths and their applications

“…It operates on the principle of using a laser to ablate particles from a bulk sample of the desired material, the particles then condense on a substrate under high vacuum (~10 −6 Torr) to form thin films [48] (figure 3). While CVD growths require reaction temperatures around 800 • C-1000 • C, PLD growths can comfortably occur around 500 • C [3,7,49]. In addition, the laser will precisely ablate a certain amount of material, and so can be 'pulsed' to achieve fine control on the final layer count of the product.…”

“…WS 2 growths have proceeded analogously to MoS 2 growths. Yao et al [7] achieved 1-cm-scale growths of multilayered WS 2 on SiO 2 . Interestingly, this sample had a mobility exceeding that of CVD grown multilayer WS 2 .…”

“…TMD band structures can be finely tuned by varying layer number or by doping [4]. This allows, for example, the inherent potential of TMDs as efficient photodetectors and light-harvesters to be utilized with great freedom [3,[5][6][7][8][9]; by doping, the band gap of a TMD can be shifted to lie within the band gap range of the solar spectrum [2]. TMDs are mechanically robust, capable of withstanding significant stress and strain [3,[10][11][12][13].…”

Recent Advances in van der Waals Heterojunctions Based on Semiconducting Transition Metal Dichalcogenides

“…A Schottky barrier can be formed at the interface between MoS 2 and graphene. [161,162] The junction between MoS 2 and graphene is a Schottky barrier, and its height can be modulated by applying gating.…”