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Maximizing the Current Output in Self-Aligned Graphene–InAs–Metal Vertical Transistors
摘要： With finite density of states and electrostatically tunable work function, graphene can function as a tunable contact for semiconductor channel to enable vertical field effect transistors (VFET). However, the overall performance, especially the output current density is still limited by the low conductance of the vertical semiconductor channel, as well as large series resistance of graphene electrode. To overcome these limitations, we construct a VFET by using single crystal InAs film as the high conductance vertical channel and self-aligned metal contact as the source-drain electrodes, resulting a record high current density over 45,000 A/cm2 at a low bias voltage of 1 V. Furthermore, we construct a device-level VFET model using resistor network method, and experimentally validate the impact of each geometry parameter on device performance. Importantly, we found the device performance is not only a function of intrinsic channel material, but also greatly influenced by device geometries and footprint. Our study not only pushes the performance limit of graphene VFETs, but also sheds light on van der Waals integration between two-dimensional material and conventional bulk material for high performance VFETs and circuits.
关键词： resistor network model,high current density,vertical transistor,graphene,van der Waals heterostructure,InAs film
更新于2025-09-23 15:23:52
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Investigation of RF and DC Performance of E-Mode In <sub/>0.80</sub> Ga <sub/>0.20</sub> As/InAs/In <sub/>0.80</sub> Ga <sub/>0.20</sub> as Channel based DG-HEMTs for Future Submillimetre Wave and THz Applications
摘要： In this paper, we systematically investigated the DC and RF behaviour of the novel Enhancement-Mode (E-Mode) Double-Gate High Electron Mobility Transistors (DGHEMTs) using Sentaurus-TCAD software. The scalability of the novel DGHEMT is also studied by analysing the short channel effects. The attractive features of the proposed DGHEMT are intrinsic In0.80Ga0.20As/InAs/In0.80Ga0.20As channel, dual silicon delta doping sheets and platinum (Pt) buried gate technology. The proposed DGHEMT with Lg = 20 nm exhibits a gm_max of 3970 mS/mm and IDS_max of 1650 mA/mm at VGS = 0.6 V and VDS = 0.8 V. The proposed DGHEMT exhibits a threshold voltage of 20 mV which indicates its E-Mode behaviour. The sub-threshold swing (SS) and DIBL values obtained for Lg = 20 nm DGHEMT at VDS = 0.5 V are 74 mV/dec and 78 mV/V respectively. The Lg = 20 nm proposed E-Mode DGHEMT also exhibit a fT and fmax of 826 and 1615 GHz respectively at VDS = 0.6 V. The computed logic gate delay for the Lg = 20 nm DGHEMT is 31.25 fS with an electron velocity under the gate of 6.4 × 107 cm/S. This excellent RF and DC behaviour of the proposed DGHEMT makes them an excellent choice for future sub-millimetre wave and THz frequency applications.
关键词： quantum well (QW),InAs,Drain induced barrier lowering (DIBL),short channel effects (SCEs),gate delay,sub-threshold swing (SS)
更新于2025-09-23 15:23:52
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Purcell Effect and Nonlinear Behavior of the Emission in a Periodic Structure Composed of InAs Monolayers Embedded in a GaAs Matrix
摘要： Enhancement of spontaneous emission in a resonant Bragg quantum well (QW) structure with 60 periods of triple InAs monolayers embedded in a GaAs matrix is studied experimentally and theoretically. From measurements of the time-resolved photoluminescence, besides the QW exciton at 1.47 eV, a specific super-radiant (SR) emission demonstrating nonlinear properties is found. The SR mode shows a near-quadratic dependence of intensity on excitation power, while its energy position follows the Bragg condition. It is revealed that the SR mode shows a peculiar non-monotonic dependence of intensity on direction, with a maximum observed at approximately 40°. The enhancement in the SR emission at a specific direction is correlated well with suggested theoretical consideration of the modal Purcell factor for periodic quantum well structures.
关键词： Purcell effect,Bragg conditions,monolayer-thick InAs quantum wells,super-radiance
更新于2025-09-23 15:22:29
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Structural, electronic and optical properties of InAs phases: by GGA-PBG and GGA-EV approximations
摘要： Structural, electronic and optical properties of InAs are investigated in the zinc-blende (ZB), rock-salt (RS) and wurtzite (WZ) phases using the full potential linearised augmented plane wave method in the framework of density functional theory (DFT). The electronic band gap of the ZB and WZ phases are improved and in good agreement with experiments by GGA-EV approximation. This compound has a direct band gap in the ZB and WZ phases in Γ point at the centre Brillouin zone and in the RS phase the conduction band crosses towards the valence band and has metallic behaviour. Also, the optical parameters such as the real and imaginary parts of epsilon, energy loss, and the refraction and reflection indices of all the phases are calculated and compared. The calculated optical properties of InAs have promising applications such as the design of optoelectronic and photonic devices.
关键词： density functional theory,optical property,GGA-EV,electronic property,InAs
更新于2025-09-23 15:22:29
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Polychromatic emission in a wide energy range from InP-InAs-InP multi-shell nanowires
摘要： InP-InAs-InP multi-shell nanowires (NWs) were grown in the wurtzite or zincblende crystal phase and their photoluminescence (PL) properties were investigated at low temperature (≈6K) for different measurement geometries. PL emissions from the NWs were carefully studied in a wide energy range from 0.7 eV to 1.6 eV. The different features observed in the PL spectra for increasing energies are attributed to four distinct emitting domains of these nano-heterostructures: the InAs island (axially grown), the thin InAs capping shell (radially grown), the crystal-phase quantum disks arising from the coexistence of InP zincblende and wurtzite segments in the same NW, and the InP portions of the NW. These results provide a useful frame for the rational implementation of InP-InAs-InP multi-shell NWs containing various quantum confined domains as polychromatic optically active components in nanodevices for quantum information and communication technologies.
关键词： photoluminescence,multi-shell nanowire,InP-InAs-InP heterostructure
更新于2025-09-23 15:22:29
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High-performance long-wavelength InAs/GaSb superlattice detectors grown by MOCVD
摘要： We demonstrate high-performance long-wavelength InAs/GaSb superlattice (SL) infrared photodetectors based on an Al-free single heterojunction grown by metalorganic chemical vapor deposition (MOCVD). The device structure consists of a mid-wavelength InAs/GaSb SL p-n junction (PN) and a long-wavelength InAs/GaSb SL n-type absorber (n), so-called PNn design, to reduce the dark current. In addition, a shallow etch technique was employed by exposing only mid-wavelength materials during pixel isolation to suppress surface leakage currents. At 77 K and a bias voltage of -0.1 V, the device exhibited a 50% cut-off wavelength at 8.0 μm, a dark current density of 2.4×10-5 A/cm2, and a peak responsivity of 2.1 A/W. Temperature dependent dark current measurement indicated diffusion-limited behavior down to 75 K. The specific detectivity was estimated to be 7.3×1011 cm·Hz1/2/W, which is comparable with that of detectors grown by molecular beam epitaxy (MBE) at similar cut-off wavelengths.
关键词： InAs/GaSb type-II superlattices,metalorganic chemical vapor deposition,heterostructure,long-wavelength infrared
更新于2025-09-23 15:22:29
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[Springer Theses] Electrical Properties of Indium Arsenide Nanowires and Their Field-Effect Transistors || Introduction
摘要： As the miniaturization and integration of solid-state electronic devices has continued to increase rapidly with the demands of high speed, low power consumption and high storage density, the conventional Si-based technology has lost their advantages on fabrication process. Therefore the technologies based on new materials gradually attract researchers’ attention. Among them, Indium Arsenide (InAs) nanowires (NWs) with high electron mobility is one of the most promising candidate. In this chapter, we introduce the advantages of InAs nanowire on electronic devices and the development status of InAs nanowire electronic devices. Also, the topic ideas and chapter arrangements of this thesis are presented.
关键词： solid-state,high electron mobility,electronic devices,InAs nanowires,miniaturization
更新于2025-09-23 15:21:21
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Excitonic complexes in InAs/InP nanowire quantum dots
摘要： InAs quantum dots embedded in InP nanowires form an important platform for basic research studies, as well as for quantum dot applications. Notably, understanding of nanowire quantum dot spectral properties is essential in both cases. Therefore, in this work we use atomistic theory to study spectra of the single exciton (X ), the biexciton (X X ), the triexciton (X X X ), and the positively and negatively charged trions (X + and X ?) con?ned in these nanostructures. We focus on the role of vertical and lateral con?nement, therefore, we systematically study a large family of quantum dots with different heights and diameters, and ?nd the important role of correlations due to presence of higher states. We ?nd that the order of excitonic binding energies is a characteristic feature of InAs/InP nanowire quantum dots being (ordered from negative to positive values): X ?, X X , and X +, with strongly bound X ?, rather weakly bound X X , and typically unbound X +. Next, we determine the key role of alloy randomness due to intermixing, which turns out to especially important for larger quantum dot heights and phosphorous contents over 40%. In selected cases, the alloying can lead to an unbound biexciton, and can even reverse ordering of excitonic lines.
关键词： InAs/InP nanowire quantum dots,atomistic theory,binding energies,alloy randomness,excitonic complexes
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Hot-Carrier Extraction in InAs/GaAs Quantum Dot Superlattice Solar Cells
摘要： We demonstrated hot-carrier (HC) extraction in GaAs solar cells containing InAs/GaAs quantum dot superlattices (QDSLs) functioning as a light absorber at 15 K. The short-circuit current density and the open-circuit voltage in the QDSL solar cells show step-wise changes as a function of the excitation photon density because of state filling under below-bandgap excitation. Furthermore, the short-circuit current density and the open-circuit voltage originated from the HC extraction were enhanced by increasing the period of the QDSL due to the improved absorptivity.
关键词： InAs quantum dots,GaAs,quantum dot superlattices,energy-selective barrier,hot-carrier solar cells
更新于2025-09-23 15:21:01
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Self-assembled InAs/InGaAsP/InP quantum dots: Intraband relaxation impacted by ultrathin GaP sublayer
摘要： The influence of an ultrathin GaP (or GaAs) sublayer on the nonradiative intraband relaxation in InAs/InGaAsP/InP quantum dots (QDs) is investigated. It is found that, based on our studies, the QDs with some heights (e.g., 1.5 nm) and GaP sublayer thicknesses (e.g., 1.03 monolayers) present the first excited state (ES) with higher state degeneracy with respect to ground state (GS), which suggests that the Auger relaxation is triggered more easily. We also find that the energy difference of the ES and GS decreases with increasing sublayer thickness, which suggests that the electron–phonon interaction is affected. This work further presents a study of intraband relaxation for an InAs/InP QD with a GaP or GaAs sublayer. It is found that there is a critical thickness of the GaP sublayer: When the sublayer is less than the critical thickness, the intraband relaxation is only determined by one-longitudinal optical (LO) phonon or two-LO phonons, which is dependent on QD heights. However, with the GaAs sublayer, QDs do not have the above feature. This finding may be helpful for designing and optimizing high-speed QD devices.
关键词： quantum dots,electron–phonon interaction,InAs/InGaAsP/InP,intraband relaxation,GaP sublayer
更新于2025-09-23 15:21:01