Wafer-Scale Patterning Synthesis of Two-Dimensional WSe₂ Layers by Direct Selenization for Highly Sensitive van der Waals Heterojunction Broadband Photodetectors

Abstract

Two-dimensional (2D) transition-metal dichalcogenides (TMDs) exhibit promising potential in fabricating highly sensitive photodetectors due to their unique electrical and optoelectrical characteristics. However, micron-sized 2D materials produced by conventional chemical vapor deposition (CVD) and mechanical exfoliation methods fail to satisfy the demands for applications in integrated optoelectronics and systems given their poor controllability and repeatability. Here, we propose a simple selenization approach to grow wafer-scale (2 in.) 2D p-WSe 2 layers with high uniformity and customized patterns. Furthermore, a self-driven broadband photodetector with a p-WSe 2 /n-Si van der Waals heterojunction has been in situ fabricated with a satisfactory responsivity of 689.8 mA/W and a large specific detectivity of 1.59 × 10 13 Jones covering from ultraviolet to short-wave infrared. In addition, a remarkable nanosecond response speed has been recorded under 0.5% duty cycle of the input light. The proposed selenization approach on the growth of 2D WSe 2 layers demonstrates an effective route to fabricate highly sensitive broadband photodetectors used for integrated optoelectronic systems.

Ferroelectricity-Driven Self-Powered Weak Temperature and Broadband Light Detection in MoS2/CuInP2S6/WSe2 van der Waals Heterojunction Nanoarchitectonics

“…Insets illustrate the corresponding SAED patterns, indicating a high crystal quality of these materials utilized in this work. The interplanar spacings of the (100) planes were observed to be 0.29, 0.56, and 0.28 nm in MoS 2 , CuInP 2 S 6 , and WSe 2 , respectively, which are consistent with the previous work. ,, …”

Y-Type Titanyl Phthalocyanine Nanoparticle and Hollow ZnS Nanotube Heterojunctions with Cavity Enhancement Effect for UV–Vis–NIR Photodetectors

“…Typically, three factors contribute to the overall noise that limits D *: the shot noise originating from dark current, Johnson noise, and thermal fluctuation noise, where the shot noise from the dark current was assumed to be the major contributor to the total noise in this case. Therefore, D * can be expressed by eqs and : , D * = A B NEP NEP = i normaln 2 ̅ R where B refers to the bandwidth, R is the responsivity, A is the device area (0.15 cm 2 here), i normaln 2 ̅ is the root-mean-square value of the spectral noise density and NEP is the noise equivalent power. The noise current of the PDs can be ascertained by measuring the noise spectral density derived from the Fourier transform of the dark current of the PDs as a function of time.…”

“…Typically, three factors contribute to the overall noise that limits D*: the shot noise originating from dark current, Johnson noise, and thermal fluctuation noise, where the shot noise from the dark current was assumed to be the major contributor to the total noise in this case. Therefore, D* can be expressed by eqs 3 and 4: 35,36…”

Recent advances in 2D transition metal dichalcogenide-based photodetectors: a review

“…52 The UV photodetector based on organic materials (a responsivity of 45 mA W −1 under illumination of 250 nm) has the potential of UV flexible imaging, exhibiting high-resolution arrays reported by T Yan et al 53 In modern electronics and optoelectronics, wafer-scale processing or growth is crucial for the development of commercially viable applications of 2D materials. 54 Kang et al obtained monolayer WS 2 and MoS 2 wafer-scale films grown on silicon dioxide (SiO 2 )-insulating substrates through a metal–organic chemical vapor deposition (MOCVD) technique. 55 The resulting films exhibit appreciable mobility (30 cm 2 V −1 s −1 ) and significant spatial homogeneity throughout the wafer.…”