category » Electronic Devices

Figure 2: Comparison of experimental and simulated strain profiles obtained from GPA, NBED, and FEA.  The two simulated strain profiles demonstrate how the revised chemistries seen in the inset improved the FEA model.
Nanoscale Stress State Characterization of InAlN/GaN Nanoribbon HEMT Structures
  • Due to its high band gap energy and superb electronic-carrier mobilities, GaN is fast becoming the material of choice for…


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Device-level Thermal Analysis of GaN-based Electronics
  • Gallium nitride (GaN)-based electronics are one of the most exciting areas of innovation for high-frequency and high-voltage semiconductor devices. Although…


Figure 2: (a) J–V characteristics of the graphene-based PbS QD devices with different polymer interlayers, demonstrating performance comparable to that of an ITO reference cell. (b) J–V characteristics of representative graphene-based P3HT devices with different polymer interlayers, compared with an ITO reference device. Insets in (a) and (b) show SEM cross-section images of the complete devices.
Graphene Cathode-based ZnO Nanowire Hybrid Solar Cells
  • Semiconducting nanowire-based solar cells have gained interest because of their potential to achieve one-dimensional charge transport pathways and large interfacial…


Towards Highly Scaled Gate Length Asymmetrically Strained Ge Nanowire p-MOSFETs
  • Ge nanowires are of interest for future sub-10-nm gate length p-MOSFETs because of the excellent electrostatic control afforded by the…


Figure 1: FEM-BEM domain decomposition and cement variables.
Partial Differential Equation-Integral Equation (PDE-IE) Solvers for Electromagnetic Scattering
  • Domain decomposition concepts, combined with other high performance scientific computation technologies, provide a framework to hybridize different solvers together and…


Figure 2:  A microphotograph of a patterned samarium cobalt magnetic thin film.  The abilities first to sputter-deposit and second to wet-etch thin films like this is critical to the successful implementation of magnetic self-assembly and are unique strengths of the MIT/Queens College effort.
Magnetically-assisted Assembly, Alignment, and Orientation of Micro-scale Components
  • The use of magnetic forces to improve fluidic self-assembly of micro-components has been investigated using Maxwell 3D to model the…


Figure 1: Output characteristics of In0.41Ga0.59Sb pFET with Lg = 0.5 μm fabricated with a stressed nitride layer. The device shows good saturation characteristics. The large gate leakage is under investigation.
Enhancement of Antimonide-based P-channel FETs using Process-induced Strain
  • For decades, growth and innovation in the microelectronics industry has been fueled by the aggressive scaling of silicon complementary metal…


Figure 2: J-V characteristics under AM1.5G illumination for representative planar (black) and nanowire-based (red) QDPV devices. Incorporating ZnO nanowires boosts the short-circuit current density (JSC) and the power conversion efficiency (PCE) by 50% and 35%, respectively. Black crosses indicate the maximum power point.
ZnO Nanowire Arrays for Enhanced Photocurrent in PbS Quantum Dot Solar Cells
  • Here we demonstrate a solution-processed ordered bulk heterojunction quantum dot (QD) solar cell with AM1.5G power conversion efficiencies of up…


Figure 2: Time evolution of source (IS), gate (IG), drain (ID), substrate (IB) leakage currents in the stress periods of Figure 1. As the OFF-state bias increases, the drain-to-substrate leakage current also increases with a minor increase in the source current. The gate leakage current is stable, presumably due to the robust MIS structure and field plate engineering.
Reliability of GaN MIS-HEMTs for Power-switching Applications
  • Engineering energy-efficient power electronic systems has recently attracted tremendous interest. Similarly, the gallium nitride metal-insulator-semiconductor high-electron-mobility transistor (GaN MIS-HEMT) fabricated…


Figure 1b: Output curves for the device shown in Figure 1a. Dotted lines correspond to experimental data, while solid lines correspond to the VS model.
A Unified Charge-current VS Compact Model for Graphene Transistors Applicable in Analog Circuit Simulations
  • With its rich physics, graphene has properties that make it a viable candidate for implementing electronic devices. For example, graphene…


Next-Generation Ultrafast Photo-Triggered Cathodes
  • State-of-the-art ultrafast cathodes are based on the photoelectric effect, where electrons are emitted from a flat surface using ultraviolet (UV)…


High-Current Cold Cathodes with Temporal and Spatial Emission Uniformity
  • Field emission arrays (FEAs) are an attractive alternative to mainstream thermionic cathodes, which are power hungry and require high vacuum…


Figure 2: Experimental nano-TLM resistance of test structures with average contact length of 80 nm. The values of ρc, Rsh, and Rshm are extracted by the 2D nano-TLM model. The insets show the two configurations in the Kelvin measurements.
Nano-scale Metal Contacts for III-V FETs
  • In the last few years, III-V compound semiconductors have emerged as a promising family of materials to replace silicon in…


Figure 2. Dit distribution for III-V MOSFET in [2], extracted from C-V characteristics in Figure 1. The Dit distribution is inside the band gap of the InP barrier layer.
A Ballistic Transport Model for III-V HEMTs and MOSFETs
  • As silicon metal-oxide-semiconductor field-effect transistors (MOSFETs) keep scaling down in size, fundamental physical limits threaten the continued improvement on their…


Figure 1. Large-area (1.5- x 1.5-cm Si/SiO2 substrate) binary nanocrystal superlattices (BNSLs) assembled from 8-nm CdSe/ZnS and 4-nm PbS/CdS core-shell QDs. (a) Fluorescence microscope image (1000x, 595-nm band filter) of BNSLs showing an average grain size of 3.2 um. (b) False color high-resolution transmission microscope (HRTEM) image and small-angle electron diffraction (CL 200 cm) pattern obtained from a single BNSL domain showing a formation of a cub-AB13 structure.
Binary Nanoparticle Superlattices Formed from Highly Luminescent Core-Shell Quantum Dots and Their Photoluminescence Properties
  • Colloidal semiconductor nanocrystals or quantum dots (QDs) offer size-tunable absorption and luminescence spectra, permitting a broad range of applications in…


Figure 1: SEM of Au nanorod array.  The nanorod geometry was tuned to match a longitudinal surface plasmon mode of an Au nanorod, which was excited by 800-nm incident laser beam.
Nanostructured Photocathodes for Compact Coherent X-ray Sources
  • Nanostructured photocathode arrays can be used as the electron sources for the compact coherent X-ray source. Femtosecond laser pulses were…


Figure 1: The three dimensions of research development for a universal village.
Universal Village: Our Desired Living Conditions
  • Due to the growing populations in cities, resources for city and village residents have become scare while costs for public…


Figure 2: A plot of external quantum efficiency versus current density, demonstrating the ~50- to 100-fold enhancement in QD-LED performance achieved by replacing core-only PbS QDs (black) with core-shell PbS-CdS QDs (green). The inset is a photograph of an array of five QD-LEDs taken with an infrared camera, with the middle device turned on and emitting at a center wavelength of λ=1242 nm .
High-performance Near-infrared Light-emitting Devices using Core-shell (PbS-CdS) Colloidal Quantum-dots
  • Near-infrared light sources integrated at room temperature with any planar surface could be realized by harnessing the broad spectral tunability,…


Figure 1: Cross sectional TEM images at the drain edge of the gate in the AlGaN/GaN HEMTs stressed at Vgs = -7 V and Vds = 43 V for 3000s in  vacuum of 1×10-7 Torr (a) dry air (b) ambient air (c) and in water saturated air (d).
TEM Studies of Degradation Studies of AlGaN High Electron Mobility Transistors
  • AlGaN/GaN High Electron Mobility Transistors (HEMT) are candidate for high-power amplifiers. However, for wide scale implementation reliability issues for these…


Figure 1: Breakdown voltage measurement using the drain current injection technique (ID = 1 mA/mm). The inset shows the circuit diagram of this technique. As the device is turned off, we observe the onset of channel breakdown before gate breakdown. This phenomenon is typical for short-channel devices.
Breakdown Voltage of High-voltage GaN FETs
  • GaN FETs offer superior advantages in high-voltage and high-temperature operation due to its large bandgap (3.4 eV) and high breakdown…


Figure 1: Schematics of nanostructured PV architectures studied in this work.  Left to right: QD PbS:ZnO pn-heterojunction (inset shows cartoon of QD passivated by organic ligand on ZnO), ClAlPc:C60 planar heterojunction with ClAlPc molecular structure, DBP:C60 planar heterojunction with DBP molecular structure, and DBP:( DBP/C60):C60 planar mixed heterojunction. All devices are sandwiched between an electron and hole transporting layer such as bathocuproine and molybdenum oxide  and ITO and Au as electrodes.
Recombination Dynamics of Charge Carriers in Nanostructured Solar Cells
  • Nanostructured solar cells attract increasing attention as a promising photovoltaic (PV) technology[1]. Generation of free charge carriers in nanostructured PV…


Figure 2: Cross-sectional SEM of an example metal-organic-metal structure formed with an evaporated Au bottom electrode, self-assembled poly(ethylene glycol) dithiol organic layer, and nanotransfer printed Au top electrode.
Tunneling Nanoelectromechanical Switches Based on Organic Thin Films
  • With the silicon-based electronics reaching physical limits that inhibit continued improvements in device performance, much research has been directed towards…


Figure 1: (a) Electron-hole bilayer TFET structure. (b) Structure with bias and current flow. Red arrows indicate current path. A positively biased top gate attracts electrons while a negatively biased bottom gate attracts holes. Vertical band-to-band tunneling (BTBT) takes place when sufficient voltage is applied across the device so that the electron and hole eigenstates overlap in energy. (c) Energy band diagram across cut shown in (a). A triangular well forms near the top gate for electrons and near the bottom gate for holes. (d) Potential barrier problem solved analytically.
Quantization in Bilayer Tunneling Transistors
  • Tunneling field-effect transistors (TFETs)[1] are promising for low-power applications due to their potential to achieve a subthreshold swing (SS) lower…


Figure 1: In-situ XPS analysis of the O 1s core level on the AlGaN surface before and after 300 °C vacuum annealing for an hour.
On the Origin of Surface Trapping Effects in AlGaN/GaN HEMTs
  • GaN-based high-electron-mobility transistors (HEMTs) are very promising candidates for the next generation of high-power and high-frequency electronics. However, trapping effects…


Figure 1: (a) Optical image of CVD-grown WSe2 flakes directly grown on SiO2/Si substrate and the back-gated devices on the flake. The triangular shape is consistent with the lattice crystal structure of WSe2 and indicates the high quality of the synthesized sample. (b) Photoluminescence signal mapping of WSe2 flakes. The darker triangle in the center demonstrates thicker islands. (c) Transfer properties of CVD WSe2 back gate devices in linear scale (left) and similog scale (right). Electrons conduct at the high positive back gate voltage region, and holes conduct at the negative bias region. (d) Output performance of WSe2 FET with different back gate bias.
Electronics on MoS2 and Other 2D Semiconductors
  • After enabling much of the modern world for more than 60 years, in the near future electronics will develop in…


Figure 1: AlGaN/GaN multi-finger device with Wg=80 mm with layout designed for solder ball, flip-chip packaging.
GaN-based Transistors for Power Electronics
  • Wide band-gap III-nitride semiconductors have excellent potential for next-generation power electronics systems.  AlGaN/GaN high-electron-mobility transistors (HEMTs) have attracted great interest…


Figure 1: A full-color device undergoing testing.
Light Modulators for Holographic Video Displays
  • In this research we seek to develop acousto-optic, guided-wave modulators in proton-exchanged lithium niobate[1] for use in holographic and other…


Figure 2: Output, transfer, output conductance, and transfer conductance plots of Lg=3 μm and Lgd= 9.5 μm device. Good agreement has been achieved between the model (curves) and measurement (circles).
MIT Virtual Source GaNFET – High Voltage (MVSG-HV) Model: A Physics-based Compact Model for HV-GaN HEMTs
  • Compact models of GaN-based high-electron-mobility transistors (HEMTs) are essential for the design of power conversion circuits such as power integrated…


Figure 2. SEM image of fin contact test structure. In this device, the Mo contact covers the top as well as the fin sidewalls. The bright lines in the fin cross-section separate the cap, channel, and buffer layers.
Towards a Self-aligned InGaAs Trigate MOSFET
  • Si-based CMOS technology is approaching the limits of its capabilities, and as a result there is extensive research into looking…


Figure 1: (a) The illustration of multiplexed all-electronic biosensors; (b) The illustration of one element of the sensor; and (c) The cross-section of one element.
Microfluidic Electronic Detection of Protein Biomarkers
  • Immunoassays use antibodies to detect protein biomarkers, with a substantial global market and significant importance for clinical practice. However, traditional…


Figure 1: Cross-sectional view of the InGaAs/GaAsSb vertical T-FET. An air-bridge structure is implemented to eliminate potential leakage paths.
Fabrication Technology for InGaAs/GaAsSb Vertical Tunnel-FETs
  • With the continuing downscaling of the modern complementary metal–oxide–semiconductor (CMOS) technology, integrated circuit power consumption has become one of the…


Figure 1:  A 30-nm InGaAs nanowire fabricated by our reactive ion etching process.
Towards a Superlattice-source Nanowire FET with Steep Subthreshold Characteristics
  • Achieving a sharp subthreshold swing (S) is crucial to enable the supply voltage scaling that is necessary to reducing power…


Figure 2: Comparison between the measurement data and model and estimation of the frequency performance of GaN HEMTs by improving each component.
High-frequency Performance of GaN HEMTs at Cryogenic Temperatures
  • The high-frequency performance of GaN-based high-electron-mobility transistors (HEMTs) has been significantly improved over the last two decades. State-of-the-art devices have…


Figure 1: Device structure of nanowire channel HEMT and its fabrication process.
High Linearity GaN HEMTs with Nanowire Channel
  • The performance of GaN-based high-electron-mobility transistors (HEMTs) has been significantly improved over the last two decades through extensive research[1][2][3]. However,…


Electronic Transport Studies of Thin Film Bi and Bi1-xSbx
  • Currently bulk Bi and BixSb1-x­ have the best known thermoelectric (TE) properties at cryogenic temperatures. These properties can be further…


Micron- and Submicron-thick Parylene Substrates for Transfer Printing and Solar Applications
  • Transfer printing of thin metal films enables the fabrication of both planar and suspended membrane electrodes for microelectromechanical (MEMS) sensors…


Figure 1: a) TEM image of highly monodisperse lead sulfide QDs capped with oleic acid ligands. The dots have a mean diameter of 6.3 nm (σ=6.0%) and show self-assembly into a hexagonal closely packed lattice system. An ideal hexagonally close packed lattice is shown in the top inset, with color used to indicate different shells of dots. The bottom inset is high-resolution TEM on a single QD to highlight its crystallinity. b) Center-to-center distance distribution of the main TEM image in Figure 1a, confirming the high degree of ordering in the film. The first major peak indicates an average center-to-center distance between nearest neighbors of 9.6 ± 0.5 nm.
Effect of Morphology in Quantum Dot Electronics
  • Quantum dots (QDs) are exciting materials because their bandgap is dependent on the dot size. The use of QDs allows…


Figure 1: Degradation of gate leakage current IGoff during high-power state stress in a step-temperature experiment from 50°C to 230°C and when the device characterization is conducted at 50°C. The numerical labels next to the data indicate the base plate temperature. A sudden increase in IGoff occurs at a base temperature stress of 170°C.
Degradation of GaN HEMTs under High-power and High-temperature Conditions
  • Due to the wide band gap energy and high breakdown electric field of GaN, heterostructure transistors made from it are…


Ionic Conduction Studies in TlBr Radiation Detector Materials
  • Detection of high-energy radiation (e.g., γ-rays) is key in nuclear non-proliferation strategies.  When a wide-band gap semiconductor detector intercepts a…