Layered Heterostructures Based on MoS₂/MoSe₂ Nanosheets Deposited on GaN Substrates for Photodetector Applications

Abstract

Due to the advanced properties of layered 2D materials, their heterostructuring with conventional 3D semiconductors is one of the promising ways to design efficient and affordable optoelectronic devices. However, systematic studies on designing 2D/3D heterojunctions with a focus on enhancing the photodetection properties are sparse in the literature. In this report, we present systematic experimental and theoretical investigations on 2D MoS 2 /MoSe 2 heterostructuring with modified GaN substrates for designing efficient photodetectors. We achieved a gradual increment in photocurrent by engineering MoS 2 and MoSe 2 as single/double heterojunctions on GaN substrates. Time-correlated single-photon counting (TCSPC) results infer significant improvement in the lifetimes of the photoexcited charge carriers for the optimized MoS 2 /MoSe 2 /e-GaN heterostructure-based photodetectors. Interestingly, photodetectors designed with double heterojunctions that maintain type-II band alignment (e-GaN/MoSe 2 /MoS 2 ) exhibit the highest photoresponsivity of 82 A/W, specific detectivity of 1.79 ×10 14 Jones, external quantum efficiency of 27,880%, and stability for over 6 months in a laboratory testing environment under the illumination of 365 nm. Density functional theory (DFT) simulations establish the superiority of double heterojunctions with staircase band alignment for efficient charge carrier transport. This study provides fundamental insights on optimizing the band alignment for desired photodetection concerning 2D/3D integration, which can be exploited for other hybrid integrated systems and applications.

WO3-NP-activated WS2 layered heterostructures for efficient broadband (254 nm–940 nm) photodetection

“…37 To further understand the role of WS 2 in activating WO 3 NPs, two different sets of device configurations, namely, D 1 ( p-Si/WO 3 ) and D 2 ( p-Si/WS 2 /WO 3 ) were prepared on the p-Si substrate using the conventional spray coating technique. 38 The adsorption of the WS 2 nanosheets and WO 3 NPs on the p-Si substrate was confirmed from thin film XRD as shown in Fig. 3(d).…”

Realization of High Current Gain for Van der Waals MoS2/WSe2/MoS2 Bipolar Junction Transistor

“…Figure 2 a illustrates the Raman spectra of the individual materials and the heterojunction area. The blue line shows the Raman spectrum of the bottom MoS 2 flake, in which the peaks at 384.3 cm −1 and 409.1 cm −1 can be observed [ 25 ]. For the WSe 2 flake, it presents two Raman peaks centered at 249.8 cm −1 and 258.1 cm −1 , consistent with previous works [ 26 , 27 , 28 ].…”

Physically Exfoliating 2D Materials: A Versatile Combination of Different Materials into a Layered Structure

“…As discussed above, 2D materials can be combined with other materials to create nanohybrids with synergistic characteristics for various applications (Table ), such as electronics/optoelectronics, ,, energy storage devices, ,,, sensors, , catalysts, ,− and thermal management . Two main types of applications are described in the following subsections.…”