Room-temperature low-threshold avalanche effect in stepwise van-der-Waals homojunction photodiodes

Abstract

Avalanche or carrier-multiplication effect, based on impact ionization processes in semiconductors, has a great potential for enhancing the performance of photodetector and solar cells. However, in practical applications, it suffers from high threshold energy, reducing the advantages of carrier multiplication. Here, we report on a low-threshold avalanche effect in a stepwise WSe2 structure, in which the combination of weak electron-phonon scattering and high electric fields leads to a low-loss carrier acceleration and multiplication. Owing to this effect, the room-temperature threshold energy approaches the fundamental limit, Ethre ≈ Eg, where Eg is the bandgap of the semiconductor. Our findings offer an alternative perspective on the design and fabrication of future avalanche and hot-carrier photovoltaic devices.

Enhancing Linearity of Light Response in Avalanche Photodiodes by Suppressing Electrode Size Effect

“…Moreover, in-depth analysis is necessary to understand the unique characteristics of three-dimensional complex structures, such as Schottky electrodes or floating guard rings. Further discussion is also needed to determine whether simpler structures, such as the two-dimensional structures mentioned in [ 26 ], can improve linearity. The emergence of this phenomenon highlights the need for a comprehensive analysis of charge accumulation behavior in complex or uniquely structured APDs.…”

Contact Geometry-Dependent Excitonic Emission in Mixed-Dimensional van der Waals Heterostructures

“…Comprising various crystallographic planes with different energies, the sidewall facets of a nanowire dictate the overall physical properties, including optical and electronic transport phenomena. , The orientations of these facets can be modulated by the bottom-up vapor–liquid–solid (VLS) growth, , which has also recently been demonstrated for vdW-layered semiconductor materials such as PbI 2 , GeS, and GeSe. − As direct bandgap semiconductors, these vdW-layered materials exhibit anisotropic excitonic behavior that is further enhanced when structured into nanowires, leading to significant emission dependencies on their crystallographic orientations. , Hence, precise control over axial orientation (i.e., layer stacking) in vdW nanowires can enable the creation of interfaces with various atomic configurations upon fabrication of heterostructures, providing opportunities for exploration that were previously inaccessible. These engineered interfaces, whether homo- or heterojunctions, play a crucial role in determining the electronic and optical properties of materials and can significantly optimize device performance, thereby enhancing functionalities across various applications including optoelectronics and energy conversion. , …”

“…These engineered interfaces, whether homo-or heterojunctions, play a crucial role in determining the electronic and optical properties of materials and can significantly optimize device performance, thereby enhancing functionalities across various applications including optoelectronics and energy conversion. 27,28 Here, we present a strategy that leverages PbI 2 vdW nanowire sidewalls to control charge transfer when they are interfaced with tungsten diselenide (WSe 2 ) monolayers, highlighting the potential of edge engineering in mixeddimensional vdW heterostructures. By tuning the axial and corresponding sidewall facet orientations of PbI 2 nanowires via controlled growth using the VLS approach and subsequently interfacing them with monolayer WSe 2 , we can engineer the layer configuration at the heterointerface to be either perpendicular or parallel.…”

“…These engineered interfaces, whether homo- or heterojunctions, play a crucial role in determining the electronic and optical properties of materials and can significantly optimize device performance, thereby enhancing functionalities across various applications including optoelectronics and energy conversion. 27 , 28 …”

Vertically stacked van der Waals heterostructures for three-dimensional circuitry elements

“…Atomically thin two-dimensional (2D) materials have recently emerged as a promising material system for electronic device applications, including field-effect transistors (FETs) [1][2][3], diodes [4,5], radio-frequency transistors [6] and memory cells [7][8][9], etc. Semiconductor p-n junctions play a crucial 5 Jinshui Miao, Yueyue Fang, and Yu Jiang contributed equally to this work. * Authors to whom any correspondence should be addressed.…”