Query: Optoelectronic Design on the Hot-carrier Photodetectors

Candidate papers:

abstract: Summary form only given. Conventional photodetectors are mostly propelled by p n junctions, where the detection wavelength is constrained by the bandgap of semiconductor material. Recently, a meta linsulator metal (MIM) configuration is demonstrated to be a promising candidate for the next generation photodetection due to its highly tunable operation wavelength, simple configuration, and possibly low cost. The MIM photodetector is operated under the principle of the hot carriers, which can be excited in the metal layer by the incident photons, and collected by the MIM junction to form measurable electrical current. For hot electron photodetection, a high and unidirectional photocurrent is strongly desired. This reveals that the total absorption of the entire system is not an ultimate target; nevertheless, a strong and asymmetrical absorption is desired eventually. However, the existing systems can hardly fulfill this stringent requirement since the incident light couples strongly with both metallic layers as well. To satisfy the inherent demands for the hot carrier photodetection, we have proposed a series of novel configurations such as coaxial Ag/ZnO/Ag nanowires, conformal grating structures, and planar multilayer cavities. Via the finite element electromagnetic simulation and the probability based analytical carrier transport calculation, we explore in detail the optical response and the electrical transport in the devices. Results show that the proposed devices can be designed flexibly and the optimized configurations exhibit superior optical and electrical performance, yielding a strong asymmetrical photoabsorption and a high unidirectional photocurrent. For instance, by asymmetrically aligning the semiconductor barrier relative to the Fermi level of metals and strongly localizing the light energy through plasmonic resonances, the conformal grating system can achieve a strong and highly asymmetrical optical absorption (top metal absorption 99% and a three fold photoresponsivity compared with the conventional grating design; by forming a planar perfect absorber at the targeted wavelength, coaxial nanowire schemes acquire a strong optical absorption and satisfy well the inherent requirement of efficient electron collection, which is predicted to be with an unbiased responsivity of 200 nA/mW.
author_names: Yaohui Zhan

Cheng Zhang

Kai Wu

Xiaofeng Li
title: Optoelectronic design on the hot carrier photodetectors
venue: 2016 Progress in Electromagnetic Research Symposium (PIERS)
year: 2016

abstract: Abstract This article presents the characteristics of a relatively new device, the quantum dot infrared (IR) photodetector, or QDIP. Recent advances in the epitaxial growth of strained heterostructures, such as Ga(In)As on GaAs, have led to the realization of coherent islands through the process of self organization. These islands behave electronically as quantum boxes, or quantum dots. The first quantum dot laser was demonstrated almost a decade ago and since then other electronic and optoelectronic devices have been reported. Theoretical and experimental studies of scattering processes and hot carrier dynamics in the quantum dots indicate that the intersubband relaxation rate of the electrons are small and may even exhibit a phonon bottleneck, under weak excitation conditions. This property, together with the three dimensional (3 D) carrier confinement and the near discrete nature of the bound states, is ideal for the design of l o n g w a v e l e n g t h intersubband detectors. Another advantage is the possibility of normal incidence operation due to the selection rules. The QDIP, therefore, has the potential of being a serious contender for applications in high temperature IR detection, and significant progress has been made since its first demonstration nearly five years ago. The properties of these fascinating and important devices are described here. Some comparisons, in terms of dark current, are made with HgCdTe detectors and quantum well IR photodetectors (QWIPs) two other successful technologies for IR detection.
author_names: Sanjay Krishna

Adrienne D Stiff-Roberts

Jamie D Phillips

Pallab K Bhattacharya

Stephen W Kennerly
title: Hot Dot Detectors. Infrared Quantum Dot Intersubband Photodetectors Are a Promising Technology for Multiwavelength IR Detection
year: 2002

abstract: Optoelectronic functionalities of photodection and light harnessing rely on the band to band excitation of semiconductors, thus the spectral response of the devices is dictated and limited by their bandgap. A novel approach, free from this restriction, is to harvest the energetic electrons generated by the relaxation of a plasmonic resonance in the vicinity of a metal semiconductor junction. In this configuration, the optoelectronic and spectral response of the detectors can be designed ad hoc just by tailoring the topology of metal structures, which has tremendous applications in solar energy harvesting and photodetection. Fully exploiting hot electron based optoelectronics yet requires a platform that combines their exotic spectral capabilities with large scale manufacturing and high performance. Herein we report the first implementation of a large area, low cost quasi 3D plasmonic crystal (PC) for hot electron photodetection, showcasing multiband selectivity in the VIS NIR and unprecedented responsivity of 70 mA/W.
author_names: F de Arquer

Agustin Mihi

Gerasimos Konstantatos
title: Multiband Tunable Large Area Hot Carrier Plasmonic Crystal Photodetectors
year: 2014

abstract: Based on Photo thermoelectric effect, by illuminating the active area of graphene based optoelectronic devices, strong electron electron interactions of the photo excited carriers along with inherit inefficiency of electron lattice energy relaxation in graphene, results in a sustained population of hot carriers. Furthermore, according to this effect, using generated hot carrier temperature profile and thermoelectric power(S)coefficient, produce a net photo thermoelectric current via the thermoelectric effect. The weakness point of this scenario is optical absorption of graphene. A promising solution to overcome this problem is using plasmonic nanostructures. Here, we show that by using a series of periodic plasmonic grating on top of electrodes, a considerable tunable asymmetry hot carrier profile on the graphene channel can be created. It is shown that by precise design of grating there would be a strong field distribution along one side of graphene sheet, which leads to an increased efficiency and responsivity of graphene based photodetector. The calculated photo thermoelectric current (ITEP shows 6 fold pattern which is qualitatively similar to photo thermoelectric patterns in experimental results.
author_names: Seyyed Asad Amirhosseini

Mohammad Karimi

Reza Safian
title: Hot carrier assisted Photo thermoelectric current using nano plasmonic structures in GFET
venue: 2016 Fourth International Conference on Millimeter Wave and Terahertz Technologies (MMWaTT)
year: 2016

abstract: Among plasmonic metals, copper (Cu) has great potential for realizing optoelectronic and photoelectrochemical hot carrier devices, owing to its CMOS compatibility and catalytic ability for electrochemical carbon dioxide reduction. Yet, copper hot carrier dynamics have received little attention and the fundamental properties of photoexcited carriers in copper are not well understood. Here, we first demonstrate that Cu nanoantennas on p type gallium nitride (p GaN) enable hot hole driven photodetection across the visible spectrum. By combining experimental internal quantum efficiency (IQE) results with ab initio theoretical modelling, we clarify the competing roles of hot carrier energy and mean free path on the performance of hot hole devices above and below the copper interband absorption threshold. By comparing Cu/p GaN hot hole and Cu/n GaN hot electron photodetectors with the same metal/semiconductor interface (Cu/GaN) we elucidate the transport characteristics of these complementary systems. In particular, we conclude that harnessing hot holes is an attractive strategy for photodetectors operating in the visible and ultraviolet regime. We anticipate that these insights about carrier transport will have a broad impact on the design of hot carrier optoelectronic devices and plasmonic photocatalysts.
author_names: Giulia Tagliabue

Joseph S DuChene

Adela Habib

Ravishankar Sundararaman

Harry A Atwater
title: Hot Hole versus Hot Electron Transport at Copper/GaN Heterojunction Interfaces.
venue: ACS nano
year: 2020

abstract: Among all plasmonic metals, copper (Cu) has the greatest potential for realizing optoelectronic and photochemical hot carrier devices, thanks to its CMOS compatibility and outstanding catalytic properties. Yet, relative to gold (Au) or silver (Ag) Cu has rarely been studied and the fundamental properties of its photoexcited hot carriers are not well understood. Here, we demonstrate that Cu nanoantennas on p type gallium nitride (p GaN) enable hot hole driven photodetection across the visible spectrum. Importantly, we combine experimental measurements of the internal quantum efficiency (IQE) with ab initio theoretical modeling to clarify the competing roles of hot carrier energy and mean free path on the performance of hot hole devices above and below the interband threshold of the metal. We also examine Cu based plasmonic photodetectors on corresponding n type GaN substrates that operate via the collection of hot electrons. By comparing hot hole and hot electron photodetectors that employ the same metal/semiconductor interface (Cu/GaN) we further elucidate the relative advantages and limitations of these complementary plasmonic systems. In particular, we find that harnessing hot holes with p type semiconductors is a promising strategy for plasmon driven photodetection across the visible and ultraviolet regimes. Given the technological relevance of Cu and the fundamental insights provided by our combined experimental and theoretical approach, we anticipate that our studies will have a broad impact on the design of hot carrier optoelectronic devices and plasmon driven photocatalytic systems.
author_names: Giulia Tagliabue

Joseph S DuChene

Adela Habib

Ravishankar Sundararaman

Harry A Atwater
title: Hot Hole versus Hot Electron Transport at Cu/ GaN Heterojunction Interfaces
year: 2020

abstract: Neuromorphic computing overcomes limitations of traditional von Neumann computing architectures by incorporating synaptic interconnections of neurons with nonlinear activation functions in a distributed neural network architecture. While some electronic neuromorphic computing demonstrations have shown significant energy efficiency improvements over their von Neumann counterparts, their scalability and throughput are still limited due to the impedance of the electrical wire interconnects. Photonic spiking neural networks (PSNNs) overcome the limitations of the electrical interconnects and potentially offer exceptionally high throughput and energy efficiency compared to electronic neuromorphic counterparts while maintaining their benefits from event driven computing capability. In this paper, we designed, prototyped, and experimentally demonstrated, for the first time to our knowledge, an optoelectronic spiking neuron inspired by the Izhikevich model incorporating both excitatory and inhibitory optical spiking inputs and producing optical spiking outputs accordingly. The optoelectronic neurons consist of three transistors acting as electrical spiking circuits, a vertical cavity surface emitting laser (VCSEL) for optical spiking outputs, and two photodetectors for excitatory and inhibitory optical spiking inputs. Additional inclusion of capacitors and resistors complete the Izhikevich inspired optoelectronic neurons, which receive excitatory and inhibitory optical spikes as inputs from other optoelectronic neurons. We developed a detailed optoelectronic neuron model in Verilog A and simulated the circuit level operation of various cases with excitatory input and inhibitory input signals. The experimental results closely resemble the simulated results and demonstrate how the excitatory inputs trigger the optical spiking outputs while the inhibitory inputs suppress the outputs. Utilizing the simulated neuron model, we conducted simulations using fully connected (FC) and convolutional neural networks (CNN) The simulation results using MNIST handwritten digits recognition show 90% accuracy on unsupervised learning and 97% accuracy on a supervised modified FC neural network. We further designed a nanoscale optoelectronic neuron utilizing quantum impedance conversion where a 200 aJ/spike input can trigger the output from on chip nanolasers with 10 fJ/spike. The nanoscale neuron can support a fanout of ~80 or overcome 19 dB excess optical loss while running at 10 GSpikes/second in the neural network, which corresponds to 100 throughput and 1000 energy efficiency improvement compared to stateof art electrical neuromorphic hardware such as Loihi and NeuroGrid. (c) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
author_names: Yun-jhu Lee

Mehmet Berkay On

Xian Xiao

Roberto Proietti

S J Ben Yoo
title: Izhikevich Inspired Optoelectronic Neurons with Excitatory and Inhibitory Inputs for Energy Efficient Photonic Spiking Neural Networks
venue: ArXiv
year: 2021

abstract: The ability to detect light over a broad spectral range is central to several technological applications in imaging, sensing, spectroscopy and communication. Graphene is a promising candidate material for ultra broadband photodetectors, as its absorption spectrum covers the entire ultraviolet to far infrared range. However, the responsivity of graphene based photodetectors has so far been limited to tens of mA W( 1) (refs 5 10) due to the small optical absorption of a monolayer of carbon atoms. Integration of colloidal quantum dots in the light absorption layer can improve the responsivity of graphene photodetectors to 1 x 10(7) A W( 1) (ref. 11) but the spectral range of photodetection is reduced because light absorption occurs in the quantum dots. Here, we report an ultra broadband photodetector design based on a graphene double layer heterostructure. The detector is a phototransistor consisting of a pair of stacked graphene monolayers (top layer, gate; bottom layer, channel) separated by a thin tunnel barrier. Under optical illumination, photoexcited hot carriers generated in the top layer tunnel into the bottom layer, leading to a charge build up on the gate and a strong photogating effect on the channel conductance. The devices demonstrated room temperature photodetection from the visible to the mid infrared range, with mid infrared responsivity higher than 1 A W( 1) as required by most applications. These results address key challenges for broadband infrared detectors, and are promising for the development of graphene based hot carrier optoelectronic applications.
author_names: Chang-Hua Liu

You-Chia Chang

Theodore B Norris

Zhaohui Zhong
title: Graphene photodetectors with ultra broadband and high responsivity at room temperature.
venue: Nature nanotechnology
year: 2014

abstract: Abstract Embedding plasmonic metal nanostructures into the semiconductor materials offers a new route to enhance the performance of photodetectors. Herein, we have reported the development of a high performance broadband photodetector based on a new core shell nanostructure, termed Ag@PbS, where Ag nanoparticle cores were synthesized by DC sputtering technique and subsequently coated by PbS shell using a convenient wet chemical method. Transmission electron microscopy, energy dispersive X ray spectroscopy, and X ray diffraction analyses provide clear evidence of core shell heterostructure formation. Close interfacial contact and Schottky barrier formation efficiently boost separation and transfer of photogenerated charge carriers across the interface of the core and shell. Moreover, the presence of Ag cores promotes photodetecting performance through the strong light absorption and scattering, abundant hot hole carriers injection and plasmonic energy transfer. Therefore, the photoconductive device delivered a broadband response range from visible to near infrared with a maximum responsivity of 26.1 A W 1, a specific detectivity of 1.8 x 1013 Jones and EQE of 4013% under 808 nm laser illumination at low light intensity 0.14 mW cm 2) Importantly, the device exhibits a fast response time of 170 ms along with excellent operational reliability and long term stability in the ambient air atmosphere. Such a result sheds new light on the design and development of novel core shell nanostructures with advanced optoelectronic properties.
author_names: Masoud Mozafari

Sh Nasresfahani

Moheb Sheikhi

H Agharezaei
title: An enhanced Vis NIR photodetector based on Ag@ PbS core shell plasmonic heterostructure
year: 2021

abstract: Abstract The rapid progress in the field of organic inorganic halide perovskite (OIHP) has led to not only >24% power conversion efficiency for photovoltaics, but also provided breakthroughs in processing of materials with tailored functional behavior. This ability to design and synthesize engineered OIHP materials has opened the possibility to develop various other optoelectronic applications. In addition to that of photovoltaics, this includes photodetector, laser, light emitting diode, X ray and gamma detector, photocatalyst, memory, transducer, transistor, and more. At this stage, the emphasis is on fundamental understanding of the underlying physics and chemistry of OIHP materials, which will assist the evaluation of device performance and provide explanations for some of the contradictory results reported in literature. This review discusses the theoretical and experimental analysis of the OIHP materials reported from various sources and considers the chemical and structural origin of their unique optoelectronic properties, correlated microstructures, and newly discovered extraordinary properties. In the first few sections, we summarize and discuss the crystallography, chemical bonding, and substitutional effects, followed by the discussion of correlated photophysics including the optical, electronic, excitonic, charge transport, and ion migration characteristics. Next, we revisit and discuss the in depth behavior of films with unique defect structure, structural disorder, morphology, and crystallization thermodynamics. Novel thermal electrical optical properties including ferroelectricity, hot carrier contribution, spin orbit coupling effect, terahertz time response, edge state discovery, etc. are rationalized considering the results debated in the community. We elaborate on the opportunities and challenges regarding stability, toxicity, and hysteresis. The viewpoint on commercialization of OIHP based solar module is presented with the goal of identifying near term opportunities. Throughout this review, the overarching goal is to provide a simplified explanation for the complex physical effects and mechanisms, underlying interconnections between different mechanisms, uncertainties reported in literature, and recent important theoretical and experimental discoveries.
author_names: Kai Wang

Dong Yang

Congcong Wu

Mohan Sanghadasa

Shashank Priya
title: Recent progress in fundamental understanding of halide perovskite semiconductors
year: 2019