Optoelectronic applications of heavily doped GaAs and MoSe₂/FePS₃ heterostructures

Optoelectronics is quickly becoming a fast emerging technology field. It refers to detect or emit electromagnetic radiation, and convert it into a form that can be read by an integrated measuring device. These devices can be a part of many applications like photodiodes, solar cells, light emitting diode (LED), telecommunications, medical equipment, and more. Due to their different applications, the semiconductor optoelectronic devices can be divided by their operating wavelength and working mechanisms. In this work, I have focused on semiconductor plasmonic systems operating in the mid-infrared and on the optical detectors made of 2D materials operating in the UV-visible spectral range. Mid-infrared plasmonic devices are very attractive for chemical sensing. Our results show that ultra-doped n-type GaAs is ideal for mid-infrared plasmonics, where the plasmon wavelength is controlled by electron concentration and can be as short as 4 μm. Ultra-doped n-type GaAs is achieved using ion implantation of chalcogenides like S and Te followed by nonequillibrium thermal annealing, namely ns-range pulsed laser melting or ms-range flash lamp annealing. I have shown that the maximum electron concentration in our GaAs layer can be as high as 7×10¹⁹ cm⁻³, which is a few times higher than that obtained by alternative techniques. In addition to plasmonic applications, the ultra-doped n-type GaAs shows negative magnetoresistance, making GaAs potential material for quantum devices and spintronic applications. UV-visible optical detectors are made of 2D materials based on van der Waals heterostructures, i.e. transition metal dichalcogenides (TMDCs) e.g. MoSe₂ and transition metal chalcogenophosphates (TMCPs) with a general formula MPX₃ where M=Fe, Ni, Mn and X=S, Se, Te. The external quantum efficiency of a self-driven broadband photodetector made of a few layers of MoSe₂/FePS₃ van der Waals heterojunctions is as high as 12 % at 532 nm. Moreover, it is shown that multilayer MoSe₂ on FePS₃ forms a type-II band alignment, while monolayer MoSe₂ on FePS₃ forms a type-I heterojunction. Due to the type-I band alignment, the PL emission from the monolayer MoSe₂ is strongly enhanced

Optoelectronic applications of heavily doped GaAs and MoSe₂/FePS₃ heterostructures

Optoelectronics is quickly becoming a fast emerging technology field. It refers to detect or emit electromagnetic radiation, and convert it into a form that can be read by an integrated measuring device. These devices can be a part of many applications like photodiodes, solar cells, light emitting diode (LED), telecommunications, medical equipment, and more. Due to their different applications, the semiconductor optoelectronic devices can be divided by their operating wavelength and working mechanisms. In this work, I have focused on semiconductor plasmonic systems operating in the mid-infrared and on the optical detectors made of 2D materials operating in the UV-visible spectral range. Mid-infrared plasmonic devices are very attractive for chemical sensing. Our results show that ultra-doped n-type GaAs is ideal for mid-infrared plasmonics, where the plasmon wavelength is controlled by electron concentration and can be as short as 4 μm. Ultra-doped n-type GaAs is achieved using ion implantation of chalcogenides like S and Te followed by nonequillibrium thermal annealing, namely ns-range pulsed laser melting or ms-range flash lamp annealing. I have shown that the maximum electron concentration in our GaAs layer can be as high as 7×10¹⁹ cm⁻³, which is a few times higher than that obtained by alternative techniques. In addition to plasmonic applications, the ultra-doped n-type GaAs shows negative magnetoresistance, making GaAs potential material for quantum devices and spintronic applications. UV-visible optical detectors are made of 2D materials based on van der Waals heterostructures, i.e. transition metal dichalcogenides (TMDCs) e.g. MoSe₂ and transition metal chalcogenophosphates (TMCPs) with a general formula MPX₃ where M=Fe, Ni, Mn and X=S, Se, Te. The external quantum efficiency of a self-driven broadband photodetector made of a few layers of MoSe₂/FePS₃ van der Waals heterojunctions is as high as 12 % at 532 nm. Moreover, it is shown that multilayer MoSe₂ on FePS₃ forms a type-II band alignment, while monolayer MoSe₂ on FePS₃ forms a type-I heterojunction. Due to the type-I band alignment, the PL emission from the monolayer MoSe₂ is strongly enhanced

Optoelectronic applications of heavily doped GaAs and MoSe₂/FePS₃ heterostructures

Optoelectronics is quickly becoming a fast emerging technology field. It refers to detect or emit electromagnetic radiation, and convert it into a form that can be read by an integrated measuring device. These devices can be a part of many applications like photodiodes, solar cells, light emitting diode (LED), telecommunications, medical equipment, and more. Due to their different applications, the semiconductor optoelectronic devices can be divided by their operating wavelength and working mechanisms. In this work, I have focused on semiconductor plasmonic systems operating in the mid-infrared and on the optical detectors made of 2D materials operating in the UV-visible spectral range. Mid-infrared plasmonic devices are very attractive for chemical sensing. Our results show that ultra-doped n-type GaAs is ideal for mid-infrared plasmonics, where the plasmon wavelength is controlled by electron concentration and can be as short as 4 μm. Ultra-doped n-type GaAs is achieved using ion implantation of chalcogenides like S and Te followed by nonequillibrium thermal annealing, namely ns-range pulsed laser melting or ms-range flash lamp annealing. I have shown that the maximum electron concentration in our GaAs layer can be as high as 7×10¹⁹ cm⁻³, which is a few times higher than that obtained by alternative techniques. In addition to plasmonic applications, the ultra-doped n-type GaAs shows negative magnetoresistance, making GaAs potential material for quantum devices and spintronic applications. UV-visible optical detectors are made of 2D materials based on van der Waals heterostructures, i.e. transition metal dichalcogenides (TMDCs) e.g. MoSe₂ and transition metal chalcogenophosphates (TMCPs) with a general formula MPX₃ where M=Fe, Ni, Mn and X=S, Se, Te. The external quantum efficiency of a self-driven broadband photodetector made of a few layers of MoSe₂/FePS₃ van der Waals heterojunctions is as high as 12 % at 532 nm. Moreover, it is shown that multilayer MoSe₂ on FePS₃ forms a type-II band alignment, while monolayer MoSe₂ on FePS₃ forms a type-I heterojunction. Due to the type-I band alignment, the PL emission from the monolayer MoSe₂ is strongly enhanced

Improved short-circuit current density of a-Si:H thin film solar cells with n-type silicon carbide layer

In this work, the performance of p-i-n hydrogenated amorphous silicon thin film solar cells by adopting n-type silicon carbide (n-SiCx:H) layer was investigated. By varying CH4/SiH4 gas flow ratio, refractive index and electrical conductivity of n-SiCx:H thin films were changed in the range of 3.4 to 3.8 and 1.48E-5 to 1.24 S/cm, respectively. Compared with solar cells with n-Si:H/Ag configuration, short-circuit current density (J (sc) ) of solar cells with n-SiCx:H/Ag configuration was improved up to 8.4%, which was comparable with that of solar cells with n-Si:H/ZnO/Ag configuration. Improved J (sc) was related with enhanced spectral response at long wavelength of 500-800 nm. It was supposed that the decreased refractive index of n-SiCx:H layer resulted in the increased back reflectance, which contributed to the improved J (sc). Our experiments demonstrated that n-SiCx:H thin films were attractive choice because they functioned both as n-layer and interlayer in back reflector, and their deposition method was compatible with preparation process of solar cells

硅氧合金薄膜结构光电特性及其在硅基薄膜太阳电池中的应用

Silicon film alloying can adjust the bandgap and reflective index of silicon film, thus it is an important material for improving solar cell performance. Mixed-phase silicon suboxide film, with the properties of high conductivity, high bandgap, and low refractive index, has been widely used as the intrinsic and doped layers in p-i-n silicon thin film solar cell. In this paper, we review the microstructure, optical and electrical characteristics of silicon suboxide films, and also its role as the window layer, absorber layer, intermediate reflector, and back reflector in silicon thin film solar cell

Electron Concentration Limit in Ge Doped by Ion Implantation and Flash Lamp Annealing

Controlled doping with an effective carrier concentration higher than 1020 cm−3 is a key challenge for the full integration of Ge into silicon-based technology. Such a highly doped layer of both p- and n type is needed to provide ohmic contacts with low specific resistance. We have studied the effect of ion implantation parameters i.e., ion energy, fluence, ion type, and protective layer on the effective concentration of electrons. We have shown that the maximum electron concentration increases as the thickness of the doping layer decreases. The degradation of the implanted Ge surface can be minimized by performing ion implantation at temperatures that are below −100 °C with ion flux less than 60 nAcm−2 and maximum ion energy less than 120 keV. The implanted layers are flash-lamp annealed for 20 ms in order to inhibit the diffusion of the implanted ions during the recrystallization process

A study of superstrate amorphous silicon thin film solar cells and modules on flexible BZO glass

Flexible thin film silicon solar modules on heat-resistant transparent flexible substrates are promising to achieve high efficiency by a combination of high-quality silicon thin films and fully monolithic series integration. In this work, performance of superstrate hydrogenated amorphous silicon (a-Si:H) thin film solar cells and modules on flexible glass using boron-doped zinc oxide (BZO) front electrode have been investigated. Compared with conventional glass, BZO thin films on flexible glass exhibited mixed structure of large-sized pyramid and small-sized grain, preferential crystalline orientations of (100) and (110), relatively lower surface roughness and scattering ability. Accordingly, compared with conventional BZO glass, a-Si:H thin film solar cells on flexible BZO glass exhibited a relative increase in open-circuit voltage, fill factor, and efficiency of 2.0, 5.5, and 3.4%, respectively. Finally, similar to 50cm(2) flexible a-Si:H thin film solar modules were prepared by fully monolithic series integration using laser scribing, and relatively higher efficiency was achieved by improving thin films uniformity

Formation and Characterization of Shallow Junctions in GaAs Made by Ion Implantation and ms-Range Flash Lamp Annealing

With the demand of aggressive scaling in nanoelectronics, further progress can be realized by integration of high mobility semiconductors, such as III–V compound semiconductors, with complementary metal‐oxide‐semiconductor (CMOS) technology. In this study, the formation of shallow n–p and p–n junctions in GaAs utilizing ion implantation of S and Zn, respectively, followed by millisecond‐range flash lamp annealing (FLA) is presented. The distribution of implanted elements obtained by secondary ion mass spectrometry (SIMS) shows that the FLA process can effectively suppress the diffusion of dopants. Simultaneously, the ms‐range annealing is sufficient to recrystallize the implanted layer and to activate the dopants. Formation of p–n and n–p junctions is confirmed by current–voltage characteristics. The ratio of reverse to forward current can reach up to 1.7 × 107 in the n‐GaAs:Zn case

Enhanced Trion Emission in Monolayer MoSe2 by Constructing a Type-I Van Der Waals Heterostructure

Funding Information: J.M.D. thanks China Scholarship Council (File no. 201706890037). L.H. thanks the National Natural Science Foundation of China (project number 61804098) and the Zhejiang Provincial Natural Science Foundation of China (project number LZ21E020002). Y.J.Z. thanks the Shenzhen Science and Technology Project under Grant no. JCYJ20180507182246321. A.V.K. also thanks the DFG for support within the projects KR 4866/2‐1 (project number 339 406129719). The computational support from the Technical University of Dresden computing cluster (TAURUS) and from High Performance Computing Center (HLRS) in Stuttgart, Germany is gratefully appreciated. The authors thank Scheumann for the metal deposition of the substrates. The nanofabrication facilities (NanoFaRo) at the Ion Beam Center at the HZDR are also gratefully acknowledged. Publisher Copyright: © 2021 The Authors. Advanced Functional Materials published by Wiley-VCH GmbHTrions, quasi-particles consisting of two electrons combined with one hole or of two holes with one electron, have recently been observed in transition metal dichalcogenides (TMDCs) and drawn increasing attention due to potential applications of these materials in light-emitting diodes, valleytronic devices as well as for being a testbed for understanding many-body phenomena. Therefore, it is important to enhance the trion emission and its stability. In this study, a MoSe2/FePS3 van der Waals heterostructure (vdWH) with type-I band alignment is constructed, which allows for carriers injection from FePS3 to MoSe2. At low temperatures, the neutral exciton (X0) emission in this vdWH is almost completely suppressed. The ITrion/Ix0 intensity ratio increases from 0.44 in a single MoSe2 monolayer to 20 in this heterostructure with the trion charging state changing from negative in the monolayer to positive in the heterostructure. The optical pumping with circularly polarized light shows a 14% polarization for the trion emission in MoSe2/FePS3. Moreover, forming such type-I vdWH also gives rise to a 20-fold enhancement of the room temperature photoluminescence from monolayer MoSe2. These results demonstrate a novel approach to convert excitons to trions in monolayer 2D TMDCs via interlayer doping effect using type-I band alignment in vdWH.Peer reviewe

Chlorine doping of MoSe2flakes by ion implantation

Funding Information: Support by the Ion Beam Center (IBC) at HZDR is gratefully acknowledged. We would like to thank Mr Scheumann for the Au-coating of the samples, Mrs Aniol for the measurements with a stylus profilometer, and Mrs Kunz for TEM specimen preparation. The funding of TEM Talos by the German Federal Ministry of Education of Research (BMBF), Grant No. 03SF0451, in the framework of HEMCP is gratefully acknowledged. A.V. K. acknowledges financial support from the DFG, project KR 4866/2-1. The authors thank the HZDR Computing Center, PRACE (HLRS, Stuttgart, Germany, Project ID: 2018184458), and TU Dresden Cluster “Taurus” for generous grants of CPU time. Publisher Copyright: © The Royal Society of Chemistry. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.The efficient integration of transition metal dichalcogenides (TMDs) into the current electronic device technology requires mastering the techniques of effective tuning of their optoelectronic properties. Specifically, controllable doping is essential. For conventional bulk semiconductors, ion implantation is the most developed method offering stable and tunable doping. In this work, we demonstrate n-type doping in MoSe2 flakes realized by low-energy ion implantation of Cl+ ions followed by millisecond-range flash lamp annealing (FLA). We further show that FLA for 3 ms with a peak temperature of about 1000 °C is enough to recrystallize implanted MoSe2. The Cl distribution in few-layer-thick MoSe2 is measured by secondary ion mass spectrometry. An increase in the electron concentration with increasing Cl fluence is determined from the softening and red shift of the Raman-active A1g phonon mode due to the Fano effect. The electrical measurements confirm the n-type doping of Cl-implanted MoSe2. A comparison of the results of our density functional theory calculations and experimental temperature-dependent micro-Raman spectroscopy data indicates that Cl atoms are incorporated into the atomic network of MoSe2 as substitutional donor impurities. This journal isPeer reviewe