Search query: Photonics and optoelectronics of 2D semiconductor transition metal dichalcogenides

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abstract: The electronic and optical properties and the recent progress in applications of 2D semiconductor transition metal dichalcogenides with emphasis on strong excitonic effects, and spin and valley dependent properties are reviewed.
author_names: Kin Fai Mak

Jie Shan
title: Photonics and optoelectronics of 2D semiconductor transition metal dichalcogenides
year: 2016

abstract: Two dimensional transition metal dichalcogenides (2D TMDs) have attracted attention for applications in electronics and photonics, as well as for the wealth of new scientific phenomena that arise at low dimensionality. Recently, the ability to grow 2D TMDs by chemical vapor deposition has opened the path to large area devices, but also to the synthesis of semiconductor alloys with tunable bandgaps. In this presentation, I will discuss our recent experimental work in exploring the optoelectronic properties of 2D MoS_2(1 x)Se_2x alloys spanning the compositional range. In particular, we report the observation of a new regime of operation where the photocurrent depends superlinearly on light intensity. We use spatially resolved photocurrent measurements on devices consisting of CVD grown monolayers to show the photoconductive nature of the photoresponse, with the photocurrent dominated by recombination and field induced carrier separation in the channel. Time dependent photoconductivity measurements show the presence of persistent photoconductivity for the S rich alloys, while photocurrent measurements at fixed wavelength for devices of different alloy compositions show a systematic decrease of the responsivity with increasing Se content associated with increased linearity of the current voltage characteristics. A model based on the presence of different types of recombination centers is presented to explain the origin of the superlinear dependence on light intensity, which emerges when the non equilibrium occupancy of initially empty fast recombination centers becomes comparable to that of slow recombination centers.
author_names: Francois Leonard
title: Optoelectronics in two dimensional semiconductor alloys (Presentation Recording)
venue: SPIE NanoScience Engineering
year: 2015

abstract: Monolayer two dimensional transition metal dichalcogenides (2D TMDCs) have gained immense attention for their desirable transport properties and direct bandgap that have led to a plethora of studies on modern nanoelectronic and optoelectronic applications. These properties are known to occur exclusively in TMDCs when thinned down to one or few monolayers. However reduced dimensionality poses a significant challenge for photonics and optoelectronics applications due to poor light absorption and emission dictated by the volume of semiconductor material. Plasmonic nanostructures have been widely studied for enhancing light matter interactions in wide variety of material systems resulting in increased emission and absorption properties. 2D Materials provide the ultimate lower limit in terms of material thickness, therefore investigation of plasmon/2D Material hybrid material systems with a specific aim to enhance light matter interactions is essential for practical optoelectronic applications. In this talk, I will discuss increased photoluminescence emission from MoS2 using both periodic plasmonic nanodisc arrays as well as a single plasmonic optical antenna. I will also describe a method for understanding and identifying the contributions of excitation and emission field enhancements to the overall photoluminescence enhancement using a tapered gold antenna. Additionally, I will describe a systematic study in which we have demonstrated increased light absorption in a monolayer WS2 film.
author_names: Koray Aydin
title: Plasmonics meet 2D materials: enhanced light matter interactions in the flatland (Conference Presentation)
year: 2018

abstract: Monolayer two dimensional transition metal dichalcogenides (2D TMDCs) have gained immense attention for their desirable transport properties and direct bandgap that have led to a plethora of studies on modern nanoelectronic and optoelectronic applications. These properties are known to occur exclusively in TMDCs when thinned down to one or few monolayers. However reduced dimensionality poses a significant challenge for photonics and optoelectronics applications due to poor light absorption and emission dictated by the volume of semiconductor material. Plasmonic nanostructures have been widely studied for enhancing light matter interactions in wide variety of material systems resulting in increased emission and absorption properties. 2D Materials provide the ultimate lower limit in terms of material thickness, therefore investigation of plasmon/2D Material hybrid material systems with a specific aim to enhance light matter interactions is essential for practical optoelectronic applications. In this talk, I will discuss increased photoluminescence emission from MoS2 using both periodic plasmonic nanodisc arrays as well as a single plasmonic optical antenna. Additionally, I will describe a systematic study in which we have demonstrated increased light absorption in a monolayer WS2 film.
author_names: Koray Aydin
title: Efficient light emission and absorption in monolayer 2D semiconductors using plasmonic nanostructures (Conference Presentation)
year: 2018

abstract: Abstract Two dimensional (2D) van der Waals (vdW) nanosheet semiconductors have recently attracted much attention from researchers because of their potentials as active device materials toward future nano electronics and optoelectronics. This review focuses on the performance and applications of state of the art vdW 2D material devices which use transition metal dichalcogenides, graphene, hexagonal boron nitride (h BN) and black phosphorous: field effect transistors (FETs) complementary metal oxide semiconductor (CMOS) inverters, Schottky diode, and PN diode. High mobility in FETs, electrical switching dynamics in CMOS inverter, photovoltaic switching for dynamic energy harvesting in PN diode, and high current driving FETs for organic light emitting diode pixel switching are demonstrated, however, remaining important issues for future electronics and photonics applications are also introduced. As a final contribution of this review, the ultimate orientations for future applications of 2D devices are forecasted and suggested, which are toward ubiquitous electronics to be a part of internet of things as integrated with existing semiconductor devices.
author_names: Kyunghee Choi

Young Tack Lee

Seongil Im
title: Two dimensional van der Waals nanosheet devices for future electronics and photonics
year: 2016

abstract: Monolayer two dimensional transition metal dichalcogenides (2D TMDCs) have gained immense attention for their desirable transport properties and direct bandgap that have led to a plethora of studies on modern nanoelectronic and optoelectronic applications. These properties are known to occur exclusively in TMDCs when thinned down to one or few monolayers. However reduced dimensionality poses a significant challenge for photonics and optoelectronics applications due to poor light absorption and emission dictated by the volume of semiconductor material. Plasmonic nanostructures have been widely studied for enhancing light matter interactions in wide variety of material systems resulting in increased emission and absorption properties. 2D Materials provide the ultimate lower limit in terms of material thickness, therefore investigation of plasmon/2D Material hybrid material systems with a specific aim to enhance light matter interactions is essential for practical optoelectronic applications. In this talk, I will discuss increased photoluminescence emission from MoS2 using both periodic plasmonic nanodisc arrays as well as a single plasmonic optical antenna. I will also describe a method for understanding and identifying the contributions of excitation and emission field enhancements to the overall photoluminescence enhancement using a tapered gold antenna. Additionally, I will describe a systematic study in which we have demonstrated increased light absorption in a monolayer WS2 film.
author_names: Koray Aydin

Nobuhiko Palo Alto Kobayashi

A Alec Talin

Albert V Davydov

M Saif Islam
title: Plasmon enhanced photon emission and absorption in monolayer, two dimensional semiconductors (Conference Presentation)
year: 2017

abstract: In the growing list of 2D semiconductors as potential successors to silicon in future devices, metal halide perovskites have recently joined the family. Unlike other conversional 2D covalent semiconductors such as graphene, transition metal dichalcogenides, black phosphorus, etc. 2D perovskites are ionic materials, affording many distinct properties of their own, including high photoluminescence quantum efficiency, balanced large exciton binding energy and oscillator strength, and long carrier diffusion length. These unique properties make 2D perovskites potential candidates for optoelectronic and photonic devices such as solar cells, light emitting diodes, photodetectors, nanolasers, waveguides, modulators, and so on, which represent a relatively new but exciting and rapidly expanding area of research. In this Review, the recent advances in emerging 2D metal halide perovskites and their applications in the fields of optoelectronics and photonics are summarized and insights into the future direction of these fields are offered.
author_names: Xiang Qi

Yupeng Zhang

Qingdong Ou

Son Tung Ha

C -W Qiu

Han Zhang

Yi-Bing Cheng

Qihua Xiong

Qiaoliang Bao
title: Photonics and Optoelectronics of 2D Metal Halide Perovskites.
venue: Small
year: 2018

abstract: Abstract The rediscovery of graphene in the recent past has propelled the rapid development of exfoliation and other thin layer processing techniques, leading to a renewed interest in transition metal dichalcogenides (TMDs) and black phosphorus (BP) in recent years. Since then, TMDs and BP have been extensively studied due to their superior electronic, photonic, and mechanical properties. Like graphene, both TMDs and BP are layered materials with strong in plane bonding and weak out of plane interactions enabling exfoliation into two dimensional (2D) layers of single unit cell thickness. However, the unique intrinsic anisotropic characteristics of BP and sizable bandgaps found in TMDs can be utilized for designing new functional devices, filling the gaps leftover by graphene. This chapter introduces the recent advances made in BP and TMD based electronic and optoelectronics devices. It begins with an overview of their crystal structures and material properties, followed by their methods of synthesis before branching into different applications in electronics and optoelectronics. The section on electronics devices summarizes the recent developments in TMD and BP based electronics, which includes the effect of metal contact, anisotropy, and gate dielectric on field effect transistors based on two dimensional materials (2DMs) new advances in hybrid and monolithic 2D complementary logic circuits, the growth in the demonstration of TMD and BP based memory devices; and lastly, the progress made in 2D printed electronics used in different types of chemical sensors. The current development in TMD and BP based optoelectronics devices is, however, sectioned into two parts. The first part covers optical modulators, semiconductor lasers, and some printed optoelectronics, while the second part reports on photodetectors based on TMD and BP. Device fabrication and techniques used in improving the responsivity, robustness, and response speed of the photodetector are discussed in these two sections as well as the methods that can be used to extend the wavelength detection limit of BP. Finally, the prospects of 2DMs in meeting the International Roadmap for Devices and Systems for the year 2020 and beyond are discussed.
author_names: Wee Chong Tan

Xin Chun Huang

Li Huang

Lin Wang

Xuewei Feng

Li Chen

Kah-Wee Ang
title: Recent advances in black phosphorus and transition metal dichalcogenide based electronic and optoelectronics devices
year: 2020

abstract: Two dimensional (2D) semiconductors, particularly the direct gap monolayer transition metal dichalcogenides (TMDs) are currently being developed for various atomically thin optoelectronic devices. However, practical applications are hindered by their low quantum efficiencies in light emissions and absorptions. While photonic cavities and metallic plasmonic structures can significantly enhance the light matter interactions in TMDs, the narrow spectral resonance and the local hot spots considerably limit the applications when broadband and large area are required. Here, we demonstrate that a properly designed distributed Bragg reflector (DBR) can be an ideal platform for light coupling enhancement in 2D TMDs. The main idea is based on engineering the amplitude and phase of optical reflection from the DBR to produce optimal substrate induced interference. We show that the photoluminescence, Raman, and second harmonic generation signals of monolayer WSe2 can be enhanced by a factor of 26, 34, and 58, respectively. The proposed DBR substrates pave the way for developing a range of 2D optoelectronic devices for broadband and large area applications.
author_names: Yen-Chun Chen

Han Yeh

Chien-Ju Lee

Wen-Hao Chang
title: Distributed Bragg Reflectors as Broadband and Large Area Platforms for Light Coupling Enhancement in 2D Transition Metal Dichalcogenides.
venue: ACS applied materials interfaces
year: 2018

abstract: It is critically important to characterize the band alignment in semiconductor heterojunctions (HJs) because it controls the electronic and optical properties. However, the well known Anderson's model usually fails to predict the band alignment in bulk HJ systems due to the presence of charge transfer at the interfacial bonding. Atomically thin 2D transition metal dichalcogenide materials have attracted much attention recently since the ultrathin HJs and devices can be easily built and they are promising for future electronics. The vertical HJs based on 2D materials can be constructed via van der Waals stacking regardless of the lattice mismatch between two materials. Despite the defect free characteristics of the junction interface, experimental evidence is still lacking on whether the simple Anderson rule can predict the band alignment of HJs. Here, the validity of Anderson's model is verified for the 2D heterojunction systems and the success of Anderson's model is attributed to the absence of dangling bonds (i.e. interface dipoles) at the van der Waal interface. The results from the work set a foundation allowing the use of powerful Anderson's rule to determine the band alignments of 2D HJs, which is beneficial to future electronic, photonic, and optoelectronic devices.
author_names: Ming-Hui Chiu

Wei-Hsuan Tseng

Hao-Ling Tang

Yung-Huang Chang

Chang Hsiao Chen

Wei-Ting Hsu

Wen-Hao Chang

Chih-I Wu

Lain-Jong Li
title: Band Alignment of 2D Transition Metal Dichalcogenide Heterojunctions
year: 2017