Query: Photocurrent Generation with Two-Dimensional van der Waals Semiconductors.

Candidate papers:

abstract: Two dimensional (2D) materials have attracted a great deal of interest in recent years. This family of materials allows for the realization of versatile electronic devices and holds promise for next generation (opto)electronics. Their electronic properties strongly depend on the number of layers, making them interesting from a fundamental standpoint. For electronic applications, semiconducting 2D materials benefit from sizable mobilities and large on/off ratios, due to the large modulation achievable via the gate field effect. Moreover, being mechanically strong and flexible, these materials can withstand large strain >10% before rupture, making them interesting for strain engineering and flexible devices. Even in their single layer form, semiconducting 2D materials have demonstrated efficient light absorption, enabling large responsivity in photodetectors. Therefore, semiconducting layered 2D materials are strong candidates for optoelectronic applications, especially for photodetection. Here, we review the state of the art in photodetectors based on semiconducting 2D materials, focusing on the transition metal dichalcogenides, novel van der Waals materials, black phosphorus, and heterostructures.
author_names: Michele Buscema

Joshua O Island

Dirk J Groenendijk

Sofya I Blanter

Gary A Steele

Herre S J van der Zant

Andres Castellanos-Gomez
title: Photocurrent generation with two dimensional van der Waals semiconductors.
venue: Chemical Society reviews
year: 2015

author_names: Michele Buscema

Joshua O Island

Dirk J Groenendijk

Sofya I Blanter

Gary A Steele

Herre S J van der Zant

Andres Castellanos-Gomez
title: Photocurrent Generation with Two Dimensional van der Waals Semiconductors
year: 2015

abstract: Strong many body interactions in two dimensional (2D) semiconductors give rise to efficient exciton exciton annihilation (EEA) This process is expected to result in generation of unbound high energy carriers. Here, we report unconventional photoresponse of van der Waals heterostructure devices resulting from efficient EEA. Our heterostructures, which consist of monolayer transition metal dichalcogenide (TMD) hexagonal boron nitride (hBN) and few layer graphene, exhibit photocurrent when photo excited carriers possess sufficient energy to overcome the high energy barrier of hBN. Interestingly, we find that the device exhibits moderate photocurrent quantum efficiency even when the semiconducting TMD layer is excited at its ground exciton resonance despite the high exciton binding energy and large transport barrier. Using ab initio calculations, we show that EEA yields highly energetic electrons and holes with unevenly distributed energies depending on the scattering condition. Our findings highlight the dominant role of EEA in determining the photoresponse of 2D semiconductor optoelectronic devices.
author_names: Eric Linardy

Dinesh K Yadav

Daniele Vella

Ivan A Verzhbitskiy

Kenji Watanabe

Takashi Taniguchi

Fabian Pauly

Maxim Trushin

Goki Eda
title: Harnessing exciton exciton annihilation in two dimensional semiconductors.
venue: Nano letters
year: 2020

abstract: Two dimensional semiconductors have a range of electronic and optical properties that can be used in the development of advanced electronic devices. However, unlike conventional silicon semiconductors, simple doping methods to monolithically assemble n and p type channels on a single two dimensional semiconductor are lacking, which makes the fabrication of integrated circuitry challenging. Here we report the reversible photo induced doping of few layer molybdenum ditelluride and tungsten diselenide, where the channel polarity can be reconfigured from n type to p type, and vice versa, with laser light at different frequencies. This reconfigurable doping is attributed to selective light lattice interactions, such as the formation of tellurium self interstitial defects under ultraviolet illumination and the incorporation of substitutional oxygen in tellurium and molybdenum vacancies under visible illumination. Using this approach, we create a complementary metal oxide semiconductor (CMOS) device on a single channel, where the circuit functions can be dynamically reset from a CMOS inverter to a CMOS switch using pulses of different light frequencies. Few layer molybdenum ditelluride and tungsten diselenide field effect transistors can be reversibly doped with different carrier types and concentrations using pulses of ultraviolet and visible light, allowing reconfigurable complementary metal oxide semiconductor circuits to be created.
author_names: Seung-Young Seo

Gunho Moon

Odongo Francis Ngome Okello

Min Yeong Park

Cheolhee Han

Soonyoung Cha

Hyunyong Choi

Han Woong Yeom

Siyoung Q Choi

Jewook Park

Moon-Ho Jo
title: Reconfigurable photo induced doping of two dimensional van der Waals semiconductors using different photon energies
year: 2020

abstract: The interlayer coupling in 2D van der Waals (vdW) heterostructures (HTS) plays the main role in generating new physics. However, the interlayer coupling is often weak, and little information on the strength of interlayer interaction in HTS is available. On the basis of density functional theory, we demonstrate that an effective electron coupling can be created in 2D C3B/C3N vdW HTS. The experimentally synthesized monolayers C3B and C3N are p and n type doped large gap semiconductors, respectively. However, the formed vdW HTS exhibits novel Dirac fermion. The strong interlayer electron coupling results in a large interlayer built in electric field and improved optical properties of the 2D C3B/C3N vdW HTS. Moreover, a simple tight binding model of C3B/C3N HTS with the nonzero interlayer hopping parameters captures the physical picture of interlayer coupling. Our results demonstrate the importance of interlayer electron coupling in the modulation of materials properties of 2D vdW HTS.
author_names: Chunmei Zhang

Yalong Jiao

Tianwei He

Steven E Bottle

Thomas Frauenheim

Aijun Du
title: Predicting Two Dimensional C3B/C3N van der Waals p n Heterojunction with Strong Interlayer Electron Coupling and Enhanced Photocurrent.
venue: The journal of physical chemistry letters
year: 2018

abstract: In two dimensional (2D) magnetic systems, large magnetic anisotropy is needed to stabilize the magnetic order according to Mermin Wagner theorem. Based on density functional theory (DFT) calculations, we propose that the magnetic anisotropic energy (MAE) of 2D ferromagnetic (FM) semiconductors can be strongly enhanced in van der Waals heterostructures by attaching a nonmagnetic semiconductor monolayer with large spin orbit coupling. We studied \mathrm{Cr}}_{2}\mathrm{Ge}}_{2}\mathrm{Te}}_{6}\mathrm{PtSe}}_{2} bilayer heterostructures, where each layer has been realized in recent experiments. The DFT calculations show that the MAE of \mathrm{Cr}}_{2}\mathrm{Ge}}_{2}\mathrm{Te}}_{6}\mathrm{PtSe}}_{2} is enhanced by 70% and the Curie temperature {T}_{C} is increased far beyond room temperature. A model Hamiltonian is suggested to analyze the DFT results, showing that both the Dzyaloshinskii Moriya interaction and single ion anisotropy contribute to the enhancement of the MAE. Based on the superexchange picture, we find that the decreased energy difference between $3d$ orbitals of Cr and $5p$ orbitals of Te contributes partially to the increase of {T}_{C} Our present work indicates a promising way to enhance the MAE and {T}_{C} by constructing van der Waals semiconductor heterostructures, which will inspire further studies on the 2D magnetic semiconductor systems.
author_names: Zhen Zhang

Bo Gu

Gang Su
title: Great enhancement of Curie temperature and magnetic anisotropy in two dimensional van der Waals magnetic semiconductor heterostructures
year: 2020

abstract: The flexible organic amine cations on the interfaces of two dimensional (2D) hybrid organic inorganic perovskite nanosheets could form relaxed structures, which would lead to exotic optoelectronic properties but are hard to understand. Here, the unusual interfacial relaxation of nanosheets exfoliated from an orthorhombic 2D lead halide perovskite, (C6H5CH2NH3)2]PbCl4, is interrogated via ultrafast second harmonic generation (SHG) spectroscopy. The in plane SHG intensity anisotropy of these nanosheets is found to decrease with reducing layer thickness. Combined first principles calculations and Monte Carlo simulations reveal that the induced second order polarization arises primarily from the (C6H5CH2NH3) cations; and these organic amine cations form significantly reorganized conformations with decreasing nanosheet thickness due to weakened van der Waals interactions. Because the orientations of organic components at the interface determine their electric properties and specifically the dipolar susceptibility, the resulting structure leads to striking changes in the SHG properties.
author_names: Wenjuan Wei

Xingxing Jiang

Liyuan Dong

Wei-Wei Liu

Xiao-Bo Han

Yan Qin

Kai Li

Wei Li

Zheyang Lin

Xian-He Bu

Peixiang Lu
title: Regulating Second Harmonic Generation by van der Waals Interactions in Two dimensional Lead Halide Perovskite Nanosheets.
venue: Journal of the American Chemical Society
year: 2019

abstract: Optical memory unit with the ability to detect and store optical signals is increasingly becoming a crucial part of advanced data communication and image sensing technology. Despite great efforts devoted to develop high performance optical memory devices based on two dimensional (2D) material, the photoelectric conversion is still limited to defect dominant photo generated carrier trapping/de trapping process at the interface of 2D materials. Here, a reconfigurable optical memory implanted with photonic programming/electric erasing operation is demonstrated based on MoS2/quantum dots (QDs) mixed dimensional heterostructure. Unique photoelectric coupling effect between MoS2 and QDs leads to a continuous n doping on MoS2 channel after light exposure removed, resulting in the generation of persistent photocurrent. Excellent optical memory characteristics such as high programming/erasing ratio, long retention time and stable operation cycles have been achieved and demonstrated to be gate tunable. Besides, multi level optical data storage with ten different states is also realized by applying a series of programmable optical signals. Owing to the unique dynamic response of mix dimensional van der Waals heterostructure to optical and electric signals, our proposed optical memory transistor may pave up a new path to explore photoelectric conversion in low dimensional system and develop high performance optoelectronics for a broad range of applications.
author_names: Yilin Sun

Yingtao Ding

Dan Xie

Mengxing Sun

Jianlong Xu

Pengfei Yang

Yanfeng Zhang

Tian-ling Ren
title: Reconfigurable optical memory based on MoS2/QDs mixed dimensional van der Waals heterostructure
year: 2021

abstract: Stimuli responsive hybrid van der Waals heterostructures (vdWHs) composed of organic molecular switches superimposed on inorganic 2D materials (2DMs) can combine the outstanding physical properties of the latter components with the virtually infinite variety of tunable functionality of molecules, thereby offering an efficient protocol for the development of high performance multifunctional materials and devices. The use of light as a remote control to modulate the properties of semiconducting 2DMs when interfaced with photochromic molecules suffers from both the limitation associated with the persistent photoconductivity characterizing the 2DMs and the finite thermal stability of the photochromic molecule in its different states. Here, we have devised a universal approach toward the fabrication of optically switchable electronic devices comprising a few nanometers thick azobenzene (AZO) layer physisorbed on 2D semiconductors supported on a trap free polymer dielectric. The joint effect of the improved 2D/dielectric interface, the molecule's light modulated dipolar doping, and the high thermal stability of cis AZO offers the highest control over the reversible and efficient charge carrier tuning in 2D semiconductors with a preserved high performance in 2D field effect transistors, as quantified in terms of carrier mobility and Ion/ Ioff ratio. The device has the potential to operate as an optical memory with four current levels and long retention time >15 h) Furthermore, by using a CMOS compatible micropatterning process, the photoswitchable resistor diode transition has been achieved on hybrid lateral heterojunction devices. Our approach is of general applicability toward the generation of high performance hybrid vdWHs for the emergence of functional and responsive devices.
author_names: Yuda Zhao

Simone Bertolazzi

Paolo Samori
title: A Universal Approach toward Light Responsive Two Dimensional Electronics: Chemically Tailored Hybrid van der Waals Heterostructures.
venue: ACS nano
year: 2019

abstract: We investigated low frequency current fluctuations, i.e. noise, in the quasi two dimensional (2D) van der Waals antiferromagnetic semiconductor FePS3 with the electronic bandgap of 1.5 eV. The electrical and noise characteristics of the p type, highly resistive, thin films of FePS3 were measured at different temperatures. The noise spectral density was of the 1/f type over most of the examined temperature range but revealed well defined Lorentzian bulges, and increased strongly near the Neel temperature TN=118 K (f is the frequency) Intriguingly, the noise spectral density attained its minimum at temperature T~200 K, which was attributed to an interplay of two opposite trends in noise scaling one for semiconductors and another for materials with the phase transitions. The Lorentzian corner frequencies revealed unusual dependence on temperature and bias voltage, suggesting that their origin is different from the generation recombination noise in conventional semiconductors. The obtained results are important for proposed applications of antiferromagnetic semiconductors in spintronic devices. They also attest to the power of the noise spectroscopy for monitoring various phase transitions.
author_names: Subhajit Ghosh

Fariborz Kargar

Amirmahdi Mohammadzadeh

Sergey Rumyantsev

Alexander A Balandin
title: Low Frequency Electronic Noise Spectroscopy of Quasi 2D van der Waals Antiferromagnetic Semiconductors
year: 2021