A5002158018- Semiconductor Quantum Structures and Devices
- GaN-based semiconductor devices and materials
- Semiconductor materials and devices
- Advancements in Semiconductor Devices and Circuit Design
- Quantum and electron transport phenomena
- Nanowire Synthesis and Applications
- ZnO doping and properties
- Ga2O3 and related materials
- Ferroelectric and Negative Capacitance Devices
- Physics of Superconductivity and Magnetism
- Metal and Thin Film Mechanics
- Photocathodes and Microchannel Plates
- Semiconductor materials and interfaces
- Integrated Circuits and Semiconductor Failure Analysis
- Electronic and Structural Properties of Oxides
- Surface and Thin Film Phenomena
- Silicon Carbide Semiconductor Technologies
- Mechanical and Optical Resonators
- Semiconductor Lasers and Optical Devices
- Advanced Chemical Physics Studies
- Plasma Diagnostics and Applications
- Advanced Materials Characterization Techniques
- Advanced Semiconductor Detectors and Materials
- Molecular Junctions and Nanostructures
- Magnetic properties of thin films
RISE Research Institutes of Sweden
2021-2023
Taiwan Semiconductor Manufacturing Company (Taiwan)
2016
KU Leuven
2015
Lund University
1996-2014
Nippon Medical School
2003
RIKEN
1997-2000
Saitama Prefecture
1999
We report a method using in situ etching to decouple the axial from radial nanowire growth pathway, independent of other parameters. Thereby wide range parameters can be explored improve properties without concern tapering or excess structural defects formed during growth. demonstrate by HCl InP The improved crystal quality etched nanowires is indicated strongly enhanced photoluminescence as compared reference obtained etching.
We demonstrate photoluminescence (PL) from self-assembling InGaN quantum dots (QDs), which are artificially fabricated on AlGaN surfaces via metalorganic chemical vapor deposition. QDs successfully by the growth mode transition to three-dimensional nanoscale island formation using “antisurfactant” silicon surface. The diameter and height of estimated be ∼10 nm ∼5 nm, respectively, an atomic-force microscope (AFM). Indium mole fraction InxGa1−xN is controlled x=∼0.22 ∼0.52 varying temperature...
The use of tetraethyltin (TESn) and dimethylzinc (DMZn) as in situ n- p-dopant precursors during particle-assisted growth InP nanowires is reported. Gate voltage dependent transport measurements demonstrate that the can be predictably synthesized either or p-type. These doped characterized based on their electric field response we find n-type doping scales over a range from 10(17) to 10(19) cm(-3) with increasing input TESn dopant molar fraction. On other hand, p-type using DMZn saturates at...
The photoluminescence emission peak energy of GaN quantum dots was observed to shift higher with decreasing dot size. This effect found be a combination blueshift from the confinement-induced electronic levels and redshift increased Coulomb induced by compression exciton Bohr radius. From this observation, absolute values binding as function size are determined.
Tunneling Field-Effect Transistors (TFET) are one of the most promising candidates for future low-power CMOS applications including mobile and Internet Things (IoT) products. A vertical gate-all-around (VGAA) architecture with a core shell (C-S) structure is leading contender to meet footprint requirements while simultaneously delivering high current drive performance specifications subthreshold swing below Boltzmann limit low power operation. In this work, VGAA nanowire GaSb/InAs C-S TFETs...
We report on an investigation of the optical properties GaN quantum dots (QDs) grown by means metalorganic vapor phase epitaxy. The growth regime for AlxGa1−xN was observed to change from two- three-dimensional, forming QDs, when Si deposited surface prior growth. These QDs showed a redshift photo luminescence (PL) energy increased Coulomb induced compression exciton Bohr radius. Furthermore, diminishing temperature-dependent shift PL with decreasing QD size caused reduction...
High-k/InAs interfaces have been manufactured using InAs surface oxygen termination and low temperature atomic layer deposition of HfO2. Capacitance–voltage (C–V) curves revert to essentially classical shape revealing mobile carrier response in accumulation depletion, hole inversion is observed, predicted minority frequency the hundred kHz range experimentally confirmed; reference samples conventional techniques show a trap dominated capacitance response. C–V fitted advanced models including...
We report on the observation of quantized conductance up to 10 K in epitaxially regrown, heterostructurally defined, 100-nm-wide Ga0.25In0.75As/InP quantum wires. In addition plateaus at integer steps 2e2/h, we observe 0.2(2e2/h), 0.7(2e2/h), and 1.5(2e2/h), indicating spin polarization zero magnetic field. Of these, first two appear evolve into one around 0.5(2e2/h) when sample is subjected a field parallel wire. The made possible by substantial improvement quality interface regrowth.
Measurements of modulation-doped Ga0.25In0.75As/InP quantum wells show, in the 〈−110〉 direction, a record electron mobility 520 000 cm2/V s at 300 mK. A difference 15% between 〈110〉 direction and is observed. This anisotropy tentatively attributed to an ordering effect. The mobilities room temperature 77 K were 16 100 170 s, respectively. By separating out ionized impurity scattering from other processes well, we conclude that low concentrations limiting mobility, while alloy has strong...
We report the first demonstration of InAs FinFETs with fin width W in range 25-35 nm, formed by inductively coupled plasma etching.The channel comprises defect-free, lattice-matched height H = 20 nm controlled use an etch stop layer incorporated into device heterostructure.For a gate length L g 1 µm, peak transconductance m,peak 1430 µS/µm is measured at V d 0.5 demonstrating that electron transport fins can match planar devices.
The fabrication and evaluation of a UV light-emitting diode (LED) incorporating GaN quantum dots as the active layer is demonstrated. were fabricated on an AlxGa1-xN (x ∼0.1) surface using Si antisurfactant. Exposing to antisurfactant prior growth enabled formation where by Stranski-Krastanov mode would not be possible. A fairly high density (1010–1011 cm-2) with controllable dot sizes was achieved. Room temperature luminescence at 360 nm clearly observed during current injection (cw) into...
We report the capability to simulate in a quantum mechanical tight-binding (TB) atomistic fashion NW devices featuring several hundred millions of atoms and diameter up 18 nm. Such simulations go far beyond what is typically affordable with today's supercomputers using traditional real space (RS) TB Hamiltonian technique. have employed an innovative mode (MS) technique instead demonstrate large speedup (up 10,000x) while keeping good accuracy (error smaller than 1 percent) compared RS NEGF...
We report on an investigation of the coupling between excitons and longitudinal optical phonons as a function GaN quantum dot size. Photoluminescence measurements dots from cryogenic temperatures up to above room temperature are presented. The experiments were performed ensembles AlN capped grown Al0.15Ga0.85N surface by means metalorganic vapor phase epitaxy. results analyzed basis Bose–Einstein-type expression describing exciton phonon lattice temperature. A reduction LO-phonon with...
We have investigated the effects of In doping on optical properties GaN films grown by gas-source molecular-beam epitaxy. Time-resolved photoluminescence was carried out to study transient epitaxial films. comparison undoped film, spontaneous emission lifetime prolonged from below 20 70 ps with In. Under high-excitation density, stimulated observed both samples. The threshold excitation density found be reduced in In-doped sample. These significant improvements are attributed effective...
InAs nanowires (NW) grown by MOCVD with diameter d as small 10 nm and gate-all-around (GAA) MOSFETs = 12-15 are demonstrated. I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</sub> 314 μA/μm, S xmlns:xlink="http://www.w3.org/1999/xlink">sat</sub> =68 mV/dec was achieved at V xmlns:xlink="http://www.w3.org/1999/xlink">dd</sub> 0.5 (I xmlns:xlink="http://www.w3.org/1999/xlink">off</sub> 0.1 μA/μm). Highest g...
The effects of N2 and O2:N2 (1:1) as ambient gases during activation annealing Mg p-type doping GaN have been investigated. purpose was to understand the mechanisms involved especially impact O2 on resulting hole concentration mobility. addition gas is known be very effective in reducing H level Mg-doped layer, but maximum achievable mobility, determined by Hall characterization, still higher with pure N2. difference explained an in-diffusion O layer acting n-dopant thus giving rise a...
Two high-k dielectric materials (Al2O3 and HfO2) were deposited on n-type (100) (110) InAs surface orientations to investigate physical properties of the oxide/semiconductor interfaces interface trap density (Dit). X-ray photoelectron spectroscopy analyses (XPS) for native oxides as-grown n-InAs epi wafers show an increase in As-oxide InOx surface. In addition, XPS that intrinsic oxide difference between surfaces eliminated by applying conventional in-situ pre-treatment (TriMethyAluminium...
The observation of zero-magnetic-field spin splitting the lowest electron subband in an ${\mathrm{Al}}_{\mathrm{x}}$ ${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$ As/ GaAs heterojunction, detected as a beating pattern Shubnikov--de Haas oscillations, is reported. observed effect induced by combination bulk ${\mathrm{k}}^{3}$ term, ascribed to inversion asymmetry host crystal and spin-orbit Rashba ${\mathrm{H}}_{\mathrm{so}}$...
Frequency (100 Hz ≤ f 1 MHz) and temperature (-50 T 20 °C) characteristics of low interface state density D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">it</sub> high-κ gate-stacks on n-InAs have been investigated. Capacitance-voltage (C-V) curves exhibit typical accumulation/depletion/inversion behavior with midgap 2 × 10 <sup xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> 4 cm xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> eV...
The optical and electrical properties of GaN films grown by using In-doping method during growth have been investigated. were on α-Al 2 O 3 (0001) substrates gas-source molecular beam epitaxy. X-ray diffraction measurements illustrate that the quality improved In-doping. Photoluminescence at 10 K show band-edge related emission was enhanced more than one order magnitude this method, while luminescence originating from D-A pair recombination structural defects, or possibly oxygen, reduced....
Microwave detection of the Shubnikov–de Haas (SdH) effect as a contact-free characterization technique for different types two-dimensional semiconductor structures is explored in low magnetic field region. The and data analysis are described. character relevance single-particle relaxation time that can be detected by this distinguished from usual transport scattering time. measured values carrier concentration agree with electrical measurements, while problem making contacts on structure...
C–V profiling of Al0.14Ga0.86N/GaN heterojunctions was performed. It found that a heterojunction with the Al0.14Ga0.86N layer on top increases electron concentration at interface, while reversed structure GaN decreases it. In accordance this result, an double to experience strongly asymmetric distribution enhancement interface closest sample surface. This effect is attributed presence piezoelectric field redistributing electrons in heterostructure.
We report on edge state transport in a ternary material, modulation-doped InP/Ga0.25In0.75As/InP quantum well, where the electron takes place highly strained Ga0.25In0.75As layer. The mobility is, even though fundamentally limited by alloy-disorder scattering, determined two-dimensional concentration. By varying distance between layer and gas we influence single particle relaxation time but not mobility. Special attention is paid to effect of dislocation formation conducting In addition Hall...
The correspondence between the E2 level (∼Ec−0.55 eV) in n-type GaN undergoing thermoionization and photoionization was established. optical cross section vicinity of threshold for this measured by means capacitance transient spectroscopy. Analysis using formulation Chantre yielded activation energy, Eo=0.85 eV, Franck–Condon parameter, dFC=0.30 eV at 90 K.