Query: Two-dimensional materials and hybrid systems for photodetection

Candidate papers:

abstract: Abstract Photodetector is an electronic component that can convert photons into electrical signals, which is ubiquitous in industry and daily life. Conventional semiconductors, such as silicon and indium gallium arsenide, have encountered limitations in photodetection due to their bandgap coverage, opacity, inflexibility, and incompatibility with photonic structures. In view of the facts, two dimensional (2D) materials, for example, graphene and transition metal chalcogenides have attracted much attention in emerging photodetectors owing to their unique electronic, optical, and mechanical properties. These 2D materials alone and its hybrid with other materials enabled new photoresponse effects and photodetection covering ultraviolet, visible, infrared, and terahertz ranges. In this chapter, we will first revisit the major photoresponse effects of 2D materials for the fundamental understanding of optical to electrical conversion processes in photodetectors. After that, a series of key figure of merits will be illustrated. Particularly, the noise in photodetectors will be carefully examined for fair evaluation of existing and new photodetectors. Then 2D materials in photodetectors will be classified and discussed in terms of photoconductive gain. Finally, this chapter will conclude with some fascinating progress of photodetection in flexible electronics as well as forthcoming bioelectronics based on 2D material photodetectors.
author_names: Ze Xiong

Jinyao Tang
title: Two dimensional materials and hybrid systems for photodetection
year: 2020

abstract: Graphene and other two dimensional materials, such as transition metal dichalcogenides, have rapidly established themselves as intriguing building blocks for optoelectronic applications, with a strong focus on various photodetection platforms. The versatility of these material systems enables their application in areas including ultrafast and ultrasensitive detection of light in the ultraviolet, visible, infrared and terahertz frequency ranges. These detectors can be integrated with other photonic components based on the same material, as well as with silicon photonic and electronic technologies. Here, we provide an overview and evaluation of state of the art photodetectors based on graphene, other two dimensional materials, and hybrid systems based on the combination of different two dimensional crystals or of two dimensional crystals and other (nano)materials, such as plasmonic nanoparticles, semiconductors, quantum dots, or their integration with (silicon) waveguides.
author_names: Frank H L Koppens

T Mueller

Phaedon Avouris

Andrea C Ferrari

Miriam Serena Vitiello

Marco Polini
title: Photodetectors based on graphene, other two dimensional materials and hybrid systems.
venue: Nature nanotechnology
year: 2014

abstract: Integration of one dimensional (1D) semiconductors with two dimensional (2D) materials into hybrid systems is identified as promising applications for new optoelectronic and photodetection devices. Herein, a self integrated hybrid ultraviolet (UV) photodetector based on InGaN nanorod arrays (NRAs) sandwiched between transparent top and back graphene contacts forming a Schottky junction has been demonstrated for the first time. The controlled van der Waals epitaxy of the vertically aligned InGaN NRA assembly on graphene on Si substrates is achieved by plasma assisted molecular beam epitaxy. Moreover, the self assembly formation mechanisms of InGaN NRAs on graphene are clarified by theoretical calculations with first principles calculations based on density functional theory. The peculiar 1D/2D heterostructure hybrid system based integrated UV photodetector simultaneously exhibits ultrafast response time ~50 ms) and superhigh photosensitivity ~105 A/W) It is highly believed that the concept proposed in this work has a great potential and can be widely applied for the next generation integrated 1D/2D nano based optoelectronic and photodetection devices.
author_names: Yulin Zheng

Wenliang Wang

Yuan Li

Jianyu Lan

Yuanyang Xia

Zhichao Yang

Xiaobin He

Guoqiang Li
title: Self Integrated Hybrid Ultraviolet Photodetectors Based on the Vertically Aligned InGaN Nanorod Array Assembly on Graphene.
venue: ACS applied materials interfaces
year: 2019

abstract: Two dimensional (2D) hybrid nanoelectronic devices stem from the combination of 2D systems or a mixture of 2D materials themselves, such as graphene, with other well defined nanostructures interacting with each other in the quantum regime and enabling exceptional characteristics. Here, this paper presents a hybrid photodetection platform consisting of a graphene/Si (Gr/Si) heterojunction in conjunction with nanoscale vacuum electronics based on a graphene/SiO2/Si (GrOS) field effect device. The responsivity of the hybrid platforms based on p Si and n Si is fully and finely tunable up to 1.2 and 0.45 A/W, respectively, which correspond to external (internal) quantum efficiencies of 235% (350% and 88% (132% respectively. The multiplication gain in the proposed hybrid device originates from the impact ionization initiated by photoinduced carrier injection into the self induced localized electric field (up to ~106 V/cm) distributed in a 2DEG region in Si. The electrons travel from the Si edge to graphene v.
author_names: Siwapon Srisonphan
title: Hybrid Graphene Si Based Nanoscale Vacuum Field Effect Phototransistors
year: 2016

abstract: In the last decade, two dimensional (2D) materials have attracted attention both in the nascent field of flexible nanotechnology as well as in more conventional semiconductor technol ogies. Within the rapidly expanding portfolio of 2D materials, the group of semiconducting transition metal dichalcogenides (TMDCs) has emerged as an intriguing candidate for various optoelectronic applications. The atomically thin profile, favorable bandgap and outstanding electronic properties of TMDCs are unique features that can be explored and applied in novel photodetecting platforms. This thesis presents highly sensitive two dimensional phototransistors made of sub nanometre thick TMDC channels. Firstly, an encapsulation route is developed to address the detrimental and, to date, uncontrollable impact of atmospheric adsorbates, which severely deteriorate detector performance. The passivation scheme improves the transport properties of TMDCs, leading to high photoconductive gain with gate dependent responsivity of 10 10^4 A/W throughout the visible, and temporal response down to 10 ms, which is suitable for imaging applications. The atomic device thickness yields ultra low dark current operation and record detectivity of 10^11 10^12 Jones for TMDC based detectors is achieved. The use of monolayer TMDCs, however, has disadvantages like limited spectral absorption due to the bandgap and limited absorption efficiency. In order to increase the absorption and to extend the spectral coverage, TMDC channels are covered with colloidal quantum dots to make hybrid phototransistors. This compelling synergy combines strong and size tunable light absorption within the QD film, efficient charge separation at the TMDC QD interface and fast carrier transport through the 2D channel. This results in large gain of 10^6 electrons per absorbed photon and creates the basis for extremely sensitive light sensing. Colloidal quan tum dots are an ideal sensitizer, because their solution processing and facile implementation on arbitrary substrates allows for low cost fabrication of hybrid TMDC QD devices. Moreover, the custom tailored bandgap of quantum dots provides the photodetector with wide spectral tunability. For photodetection in the spectral window of NIR/SWIR, which is still dominated by expensive and complex epitaxy based technologies, these hybrid detectors have the potential to favorably compete with commercially available systems. The interface of the TMDC QD hybrid is of paramount importance for sensitive detector operation. A high density of trap states at the interface is shown to be responsible for inefficient gate control over channel conductivity, which leads to high dark currents. To maintain the unique electrical field effect modulation in TMDCs upon deposition of colloidal quantum dots, a passivation route of the interface with semiconducting metal oxide films is developed. The buffer layer material is selected such that charge transfer from QDs into the channel is favored. The retained field effect modulation with a large on/off ratio allows operation of the phototransistor at significantly lower dark currents than non passivated hybrids. A TMDC QD phototransistor with an engineered interface that exhibits detectivity of 10^12 10^13 Jones and response times of 12 ms and less is reported. In summary, this work showcases prototype photodetectors made of encapsulated 2D TMDCs and TMDC QD hybrids. Plain TMDC detectors have potential for application as flexible and semi transparent detector platforms with high sensitivity in the visible. The hybrid TMDC QD device increases its spectral selectivity to the NIR/SWIR due to the variable absorption of the sensitizing quantum dots and reaches compelling performance thanks to im proved light matter interaction and optimized photocarrier generation.
author_names: Dominik Kuffer
title: Photodetectors based on low dimensional materials and hybrid systems
year: 2016

abstract: for Applications in Plasmonics, Nanophotonics and Energy Alexandra Boltasseva and Vladimir M. Shalaev School of Electrical&Computer Engineering and Birck Nanotechnology Center, Purdue University Two dimensional (2D)and quasi 2D materials have enabled a variety of promising designs and demonstrations of miniaturized, tunable optical devices, owing to their extraordinary light confinement, tailorability of the optical properties and dynamic tunability. In this talk, our recent research progress on utilizing 2D materials such as graphene and MXene a class of emerging 2D transition metal carbides, nitrides and carbon nitrides will be discussed. We have previously demonstrated that the surface plasmon (SP) resonance of a hybrid plasmonicgraphene structure can be electrically modulated thus bringing a thought after electrical tunability to the area of plasmonics. By utilizing the intrinsic graphene SPs excited in graphene nanoribbons, stronger electromagnetic field confinement and wider spectral tunability have been realized compared to purely plasmonic or hybrid metal graphene structures. Being a gapless and excellent thermoelectric material, graphene also holds a great promise for ultra wideband and ultra fast photodetection. However, its performance is mainly limited by the poor optical absorption thus low photo sensitivity in pristine graphene. We designed a snowflake fractal metasurface on a graphene layer that showed high absorption in the visible range that is non resonant and polarization insensitive, thus enhancing the sensitivity of graphene photodetector by an order of magnitude. With the photothermoelectric effect being the dominant photo carrier generation effect in graphene, the approach to further enhancing graphene photo sensitivity lies in creating a strongly localized temperature profile. We propose to utilize plasmonic systems for efficient conversion of optical energy to heat to further enhance the device sensitivity. MXenes, a class of 2D nanomaterials formed of transition metal carbides and carbon nitrides, are also a promising material platform for tailorable nanophotonics. They offer a number of unusual properties and are being applied to realize novel electromagnetic shields, metal ion batteries, super capacitors, lasers, and sensors. We utilized the plasmonic response of titanium carbide (Ti3C2Tx) MXene thin films in the near infrared spectral window to create a metamaterial for broadband absorption. Optical losses inherent to bulk MXene together with strongly localized SP resonances in Ti3C2Tx nanostructures enable efficient broadband absorption. We also demonstrated random lasing behavior in a disordered metamaterial composed of 2D Ti3C2Tx MXene. In contrast to previously reported random laser systems where the optical property of scatterers is static, the relative permittivity of Ti3C2Tx MXene flakes can be engineered under optical pumping due to their strong saturable absorption. Our investigation indicates that this nonlinear response of Ti3C2Tx MXene flakes enables dynamically tunable random lasing. Considering the diversity of the MXene family, this metamaterial design opens a new avenue to advanced control of lasing properties for photonic applications. This abstract was submitted to PQE 2019, the 49th Winter Colloquium on the Physics of Quantum Electronics.
author_names: Alexandra Boltasseva

Vladimir M Shalaev
title: Two Dimensional and Quasi 2D Materials for Applications in Plasmonics, Nanophotonics and Energy
year: 2018

abstract: Here we demonstrate novel self powered photodetection using silver (Ag) nanoparticle loaded two dimensional graphitic carbon nitride (g C3N4) nanosheets triggered by Poly vinylidene fluoride (PVDF) based flexible piezoelectric nanogenerators. Self poled PVDF based nanogenerator has been obtained upon exploiting pristine g C3N4 nanosheets as a filler material within the PVDF matrix. The fabricated nanogenerator devices are found to be highly efficient in generating maximum voltage of 2.3 V and maximum power 110 Watt/cm2, upon finger tapping. Further, the integration of an additional layer of plasmonic Ag nanoparticle loaded g C3N4 nanosheets, has led to a significant enhancement of photoresponse. The hybrid plasmonic nanogenerator (with a strain of 0.021% has resulted in self powered photodetection with a photo to dark current ratio of ~60, as compared to unstrained device ~2.0) In contrast to the usual behaviour (positive photoresponse) the exposure of an ultraviolet light lowers the output current indicating a negative photoresponse reported for the first time in such system. The origin of such negative photoresponse has been attributed to the screening of piezopotential of PVDF by photogenerated carriers of g C3N4 nanosheets. On the other hand, visible light induced positive photoresponse has originated from the increment in current indicating the useful role of Ag nanoparticles in plasmon induced hot electron transfer process.
author_names: Sayan Bayan

D Bhattacharya

Rajib Kumar Mitra

Samit Kumar Ray
title: Self powered flexible photodetectors based on Ag nanoparticle loaded g C3N4 nanosheets and PVDF hybrids: Role of plasmonic and piezoelectric effects.
venue: Nanotechnology
year: 2020

abstract: Light matter interaction in graphene can be engineered and substantially enhanced through plasmonic sensitization, which has led to numerous applications in photodetection, sensing, photocatalysis and spectroscopy. The majority of these designs have relied on conventional plasmonic materials such as gold, silver and aluminum. This limits the implementation of such devices to the ultraviolet and visible regimes of the electromagnetic spectrum. However, for many practical applications, including those relevant to security and defense, the development of new strategies and materials for sensing and detection of infra red (IR) light is crucial. Here we use surface enhanced Raman spectroscopy (SERS) for direct visualization and estimation of enhanced light matter interaction in graphene in the mid IR regime, through sensitization by an unconventional plasmonic material. Specifically, we fabricate a hybrid device consisting of a single layer graphene and a two dimensional array of nanodiscs of aluminum doped zinc oxide (AZO) which is a highly doped semiconductor, exhibiting plasmonic resonance in the mid IR. We find that the enhancement in the SERS signal of graphene is of similar magnitude to what has been achieved previously in the visible using conventional plasmonic materials. Our results establish the potential of such hybrid systems for graphene based optical and optoelectronic applications in the mid IR.
author_names: Debadrita Paria

Vaisakh Vadakkumbatt

Pramod Ravindra

Sushobhan Avasthi

Ambarish Ghosh
title: Unconventional plasmonic sensitization of graphene in mid infrared
venue: Nanotechnology
year: 2021

abstract: Two dimensional crystals such as graphene and transition metal dichalcogenides demonstrate a range of unique and complementary optoelectronic properties. Assembling different two dimensional materials in vertical heterostructures enables the combination of these properties in one device, thus creating multifunctional optoelectronic systems with superior performance. Here, we demonstrate that graphene/WSe2/graphene heterostructures ally the high photodetection efficiency of transition metal dichalcogenides with a picosecond photoresponse comparable to that of graphene, thereby optimizing both speed and efficiency in a single photodetector. We follow the extraction of photoexcited carriers in these devices using time resolved photocurrent measurements and demonstrate a photoresponse time as short as 5.5 ps, which we tune by applying a bias and by varying the transition metal dichalcogenide layer thickness. Our study provides direct insight into the physical processes governing the detection speed and quantum efficiency of these van der Waals heterostuctures, such as out of plane carrier drift and recombination. The observation and understanding of ultrafast and efficient photodetection demonstrate the potential of hybrid transition metal dichalcogenide based heterostructures as a platform for future optoelectronic devices.
author_names: Mathieu Massicotte

P Schmidt

Fabien Vialla

Kevin Gerd Schadler

Antoine Reserbat-Plantey

Kenji Watanabe

Takashi Taniguchi

Klaas-Jan Tielrooij

Frank H L Koppens
title: Picosecond photoresponse in van der Waals heterostructures.
venue: Nature nanotechnology
year: 2016

abstract: Two dimensional semiconducting transition metal dichalcogenides (TMDCs) have recently become attractive materials for several optoelectronic applications, such as photodetection, light harvesting, phototransistors, light emitting diodes, and lasers. Their bandgap lies in the visible and near IR range, and they possess strong excitonic resonances, high oscillator strengths, and valley selective response. Coupling these materials to optical nanocavities enhances the quantum yield of exciton emission, enabling advanced quantum optics and nanophotonics devices. Here, we review the state of the art advances of hybrid exciton polariton structures based on monolayer TMDCs coupled to plasmonic and dielectric nanocavities. We discuss the optical properties of 2D WS2, WSe2, MoS2 and MoSe2 materials, paying special attention to their energy bands, photoluminescence/absorption spectra, excitonic fine structure, and to the dynamics of exciton formation and valley depolarization. We also discuss light matter interactions in such hybrid exciton polariton structures. Finally, we focus on weak and strong coupling regimes in monolayer TMDCs based exciton polariton systems, envisioning research directions and future opportunities for this material platform.
author_names: Alexander E Krasnok

Sergey Lepeshov

Andrea Alu
title: Nanophotonics with 2D transition metal dichalcogenides [Invited]
venue: Optics express
year: 2018