Van der Waals interfaces in multilayer junctions for ultraviolet photodetection

Abstract

Developments in semiconductor science have led to the miniaturization and improvement of light detection technologies for many applications. However, traditional pn-junctions or three-dimensional device geometries for detection of ultraviolet (UV) light are still limited by the physical properties of the semiconductors used, such as the small penetration depth of UV light in silicon. Van der Waals (vdW) semiconductors and their pn-junctions can offer an alternative solution due to their optical properties and thin pn-junction region. Here, we report on a multi-layer junction that combines single layer graphene and vdW semiconductors (p-GaSe and n-In2Se3) with strong optical absorption in the UV range. The junctions have broadband spectral response (0.3-1.0 μm) and high photoresponsivity under forward and reverse bias, or without any externally applied voltage. The photoresponse differs from that of a traditional pn-junction diode as it is governed by charge transport across thin layers and light-current conversion at three vdW interfaces (e.g. the graphene/GaSe, GaSe/In2Se3 and In2Se3/graphene interfaces). The type-II band alignment at the GaSe/In2Se3 interface and electric field at the three vdW interfaces are beneficial to suppress carrier recombination for enhanced photoresponsivity (up to ~102 A/W) and detectivity (up to ~1013 Jones), beyond conventional UV-enhanced silicon detection technology.

High-Sensitivity and Fast-Speed UV Photodetectors Based on Asymmetric Nanoporous-GaN/Graphene Vertical Junction

“…A 50 nm-thick Au layer was deposited on a Si/SiO 2 substrate as the bottom electrode using e-beam evaporation, and then, the nanoporous GaN film was transferred to one of the electrode fingers by the dry transfer method . A patterned monolayer graphene (Gr) layer, transferred by a needle-assisted transfer process, was used as the top electrode to connect the top surface of the nanoporous GaN film and another Au electrode. The detailed preparation process of the patterned monolayer graphene has been described in our previous work .…”

Multi‐Controllability of Ambipolar Photoconductivity in Transition Metal Dichalcogenides Van der Waals Heterostructures

“…In both operation modes, i.e., with and without the source‐drain bias V ds , the responsivity of our heterojunction PD under deep UV illumination are the highest among the reported PDs based on 2D materials and conventional semiconductors [ 25,41–44 ] (Table S1, Supporting Information). It is also comparable to the recently reported FePSe 3 /MoS 2 heterostructure PD at the same illumination wavelength (3.36 × 10 4 AW −1 at 265 nm at V ds = 4 V), [ 25 ] in which a gold back reflector was employed to enhance the light absorption at the heterostructure and shorten the transport distance of the photogenerated charge carriers.…”

“…A maximum responsivity of 140 mAW −1 is attained at V ds = 0 V that is higher than most of the reported UV PDs. [25,[41][42][43][44]…”

High‐Sensitive and Fast Speed UV Photodetector Based on HfSe2/InSe Heterostructure

“…Nevertheless, their development and wide applications are greatly hindered by the strict requirement of lattice match during the epitaxial growth, high operation bias, and high cost. To date, with the rapid development of 2D materials, the wide bandgap h‐BN, [ 17,18 ] BP‐ReS 2 , [ 19 ] GaN/PdSe 2 , [ 20 ] GaN/PtSe 2 , [ 21 ] GaSe/In 2 Se 3 , [ 22 ] FePSe 3 [ 23 ] and graphene/PtSe 2 /β‐Ga 2 O 3 2D/3D heterostructure [ 24 ] demonstrated excellent SBUV detection. However, high‐performance SBUV detectors with both fast speed and high sensitivity is still a challenge.…”