Ultrasensitive Phototransistor Based on WSe₂–MoS₂ van der Waals Heterojunction

Abstract

Band engineering using the van der Waals heterostructure of two-dimensional materials allows for the realization of high-performance optoelectronic devices by providing an ultrathin and uniform PN junction with sharp band edges. In this study, a highly sensitive photodetector based on the van der Waals heterostructure of WSe 2 and MoS 2 was developed. The MoS 2 was utilized as the channel for a phototransistor, whereas the WSe 2 −MoS 2 PN junction in the out-of-plane orientation was utilized as a charge transfer layer. The vertical built-in electric field in the PN junction separated the photogenerated carriers, thus leading to a high photoconductive gain of 10 6 . The proposed phototransistor exhibited an excellent performance, namely, a high photoresponsivity of 2700 A/W, specific detectivity of 5 × 10 11 Jones, and response time of 17 ms. The proposed scheme in conjunction with the largearea synthesis technology of two-dimensional materials contributes significantly to practical photodetector applications.

A review of molybdenum disulfide (MoS2) based photodetectors: from ultra-broadband, self-powered to flexible devices

“…Photodetectors were also developed from the WSe 2 and MoS 2 vdWHs where MoS 2 was used as a channel in the phototransistor. 374 The MoS 2 vdWHbased phototransistor showed high photoresponsivity of 2700 A W À1 , detectivity of 5 Â 10 11 Jones, and response speed of 17 ms. In these phototransistors, the vertical built-in electric eld in the WSe 2 -MoS 2 p-n junction separated the photoexcited charge carriers, which yielded a photoconductive gain of 10 6 .…”

Arrayed MoS2–In0.53Ga0.47As van der Waals Heterostructure for High‐Speed and Broadband Detection from Visible to Shortwave‐Infrared Light

“…In recent, transition metal dichalcogenides (TMDs) such as molybdenum disulfide (MoS 2 ) have received significant research interests due to excellent material properties of strong light absorption, high in‐plane mobility despite atomically thin layer. [ 1–3 ] Using these advantages, many research groups have reported various semiconductor devices regarding field‐effect transistors (FETs), photodetectors (PDs), energy harvesters, and sensors. [ 1–5 ] Among those devices, PDs are one of the key devices because the future Internet‐of‐things (IoT) regime will much require many optical sensors for imaging, communications, and various healthcare sensors.…”

“…[ 1–3 ] Using these advantages, many research groups have reported various semiconductor devices regarding field‐effect transistors (FETs), photodetectors (PDs), energy harvesters, and sensors. [ 1–5 ] Among those devices, PDs are one of the key devices because the future Internet‐of‐things (IoT) regime will much require many optical sensors for imaging, communications, and various healthcare sensors. [ 6 ] Thus, several groups have tried to exploit outstanding optoelectronic properties of MoS 2 for high‐performance PDs, which could absorb the visible light up to 1 µm depending on thickness.…”

“…To overcome these issues, heterojunction PDs based on 2D‐2D and 2D–3D van der Waals heterostructure have been emerged as a promising alternative to fully utilize their inherent material properties. [ 1–3,6,9–11 ] So, the various MoS 2 ‐based heterojunction devices have been demonstrated showing enhanced detection performances and broadened spectral range in MoS 2 /Si, MoS 2 /GaAs, MoS 2 /GaN, MoS 2 /black phosphorous, etc. [ 2,6,12,13 ] Although there are many reports regarding heterojunction PDs, most of the MoS 2 ‐based devices have shown only a slight extension of wavelength coverage to approximately 1100 nm of Si materials, whereas there are strong demands on wider‐spectral PDs beyond 1300 nm for future optical communications and broadband imaging.…”

Tuning Valleys and Wave Functions of van der Waals Heterostructures by Varying the Number of Layers: A First‐Principles Study

“…[23,24] Thus, one can speak of new physical phenomena in these materials and they are being considered for a wide range of applications, ranging from ultrafast charge separation, (opto)electronics through quantum information processing or valleytronics. [17,19,[25][26][27][28][29][30] A large variety of 2L vdW HS has recently been investigated on the basis of experiments and theory, [11,13,15,16,18,19,6,22,[30][31][32][33][34][35] including these constituting of layers from Group 6 TMDCs. [5][6][7]11,16,[36][37][38] For instance, Kim et al, [19] reported ultra-long valley lifetime in MoS 2 /WSe 2 heterostructures, which was explained by the spatial confinement of electrons and holes in different layers.…”