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2 edition of Photo-generated shift and injection currents in wurtzite semiconductors. found in the catalog.

Photo-generated shift and injection currents in wurtzite semiconductors.

Norman Laman

# Photo-generated shift and injection currents in wurtzite semiconductors.

## by Norman Laman

Published .
Written in English

Subjects:
• Physics Theses.

Subsequent experiments measured both the shift and injection currents in CdSe and CdS via the emitted THz radiation following excitation by sub-ps optical pulses. Shift and injection current were created in CdSe by near bandgap optical excitation and in CdS by 3.0 eV photons. The THz radiation from both shift and injection currents in both CdSe and CdS follows the expected dependence on the optical polarization and sample orientation. All of the THz signals show the expected linear power dependence. The measured shift and injection current tensor amplitudes for CdSe at 1.78 eV are sigmazzz = 1.5 x 10-6A V-2 and etaxzx = 1.5 x 10 8A V-2s-1, respectively. The shift and injection currents vanish for excitation photon energies below the electronic bandgap. For CdS, excited at 3.0 eV, the measured shift and injection current tensor amplitudes are sigmazzz = 8 x 10-6A V-2 and eta xzx = 4 x 108A V-2s -1, respectively.Two different types of photocurrents, shift and injection currents, are generated in the wurtzite semiconductors CdSe (Eg = 1.75eV) and CdS (Eg = 2.5eV). Shift and injection currents are electrical currents induced via a second-order optical nonlinearity in semi-conductors when excited with above bandgap optical radiation. Shift currents arise from a difference between the centre of charge for the valence and conduction states, while injection currents are generated due to a quantum interference between polarization-dependent absorption pathways.Injection currents were first measured in CdSe via silver electrodes which were deposited on the semiconductor sample surface. The voltage was measured across the electrodes when the sample surface between the electrodes was illuminated. Excitation with a 5 mW cw HeNe laser at 1.96 eV results in a voltage of 110 muV, providing an estimate of the injection current tensor element etaxzx of ∼5 x 107A V-2s-1.The temporal behavior of the currents was measured by the THz radiation, and in principle a difference between the shift and injection currents is expected. However, the temporal resolution of the CdSe experiments is limited by the optical pulse width of 200 fs. The CdS experiments used shorter optical pulses of 60 fs, but the temporal resolution is limited by the electro-optic sampling crystals. No temporal difference between the EO traces from shift and injection current in CdS was measured. This implies that the momentum scattering time is less than 100 fs.

Edition Notes

The Physical Object ID Numbers Contributions Van Driel, Henry. Pagination 102 leaves. Number of Pages 102 Open Library OL19475735M ISBN 10 0494028866

In the past decade, light-emitting diodes (LEDs) based on wideband gap semiconductor have attracted considerable attention due to its potential optoelectronic applications in illumination, mobile appliances, automotive and displays [].Among the available wide band gap semiconductors, zinc oxide, with a large direct band gap of eV, is a . Internal structure of acceptor-bound excitons in wide-band-gap wurtzite semiconductors, , ald, and Bo Monemar, Physical Review B 84, , () Google Scholar Band edge smearing in solid solutions, S.D Baranowski and , Soviet Physics.

Based on the above relation, the biaxial stress under different current injections is determined through the E 2 phonon frequency shift Δω with respect to unstrained GaN. Given that the E 2 phonon frequency in the stress-free GaN is known to be located at ± cm −1 20, the calculated compressive stress of GPa in Fig. 2(c) is considered reasonable in GaN-based . This chapter is from the book Properties, Processing and Applications of Gallium Nitride and Related Semiconductors, which contains over articles exploring the latest insights and numeric data on gallium nitride. Papers include information on processing and the exploitation of GaN - together with the related semiconductors AlN, InN and ternary semiconductors - in .

Effect of temperature and injection current on characteristics of TO-CAN packaged Fabry-Perot laser diode. / Han, Jae Ho; Park, Sung Woong. In: Current Applied Physics, Vol. 7, No. 1, , p. Research output: Contribution to journal › Article. the pressure dependence of the band gap for wurtzite GaN is determined at9Kupto73kbar and at K to 55 kbar by using the I2 line of the PL spectrum. In the course of this work the effect of applied pressure on other radiative fea-tures at 9 and K is also examined. The unintentionally doped wurtzite GaN epilayer under.

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### Photo-generated shift and injection currents in wurtzite semiconductors by Norman Laman Download PDF EPUB FB2

Ultrafast shift and injection currents observed in wurtzite semiconductors via emitted terahertz radiation N. Laman, M. Bieler,a and H. van Drielb Department of Physics and Institute for Optical Sciences, University of Toronto, Toronto, Canada M5S 1A7 Received 17 June ; accepted 7 October ; published online 18 November   Two different types of photocurrents, shift and injection currents, are generated in the wurtzite semiconductors CdSe (Eg = eV) and CdS (Eg = eV).

Shift and injection currents are electrical currents induced via a second-order optical nonlinearity in semi-conductors when excited with above bandgap optical : Norman Laman.

Shift and injection currents are generated in the wurtzite semiconductors CdSe and CdS at K using above-band-gap (ℏω≫E g) femtosecond pulses and. R.J. Lad, in Handbook of Surface Science, Wurtzite (MO) The wurtzite structure consists of a hexagonal close-packed array of oxygen anions with half of the tetrahedral interstices occupied by metal cations (Fig.

); oxides having the wurtzite structure include ZnO and are several important wurtzite surfaces: the cation-terminated () basal. We observe second-order rectification and shift currents in GaAs at K using fs pulses at and μm, respectively.

For the same low. This article reviews the current status of spin dynamics in semiconductors which has achieved much progress in the recent years due to the fast growin.

49, 50 An estimate of the shift vector was extracted by comparing a phenomenological model for shift currents with the experiments on wurtzite semiconductors, 51 while a shift current.

•Semiconductors: Conductivity can be varied by several orders of magnitude. •It is the ability to control conductivity that make semiconductors useful as “current/voltage control elements”. “Current/Voltage control” is the key to switches (digital logic including microprocessors etc), amplifiers, LEDs, LASERs, photodetectors, etc.

Gallium Nitride (GaN) based inverted p-i-n junction and InGaN/GaN quantum well LEDs have been demonstrated using Laser Molecular Beam Epitaxy techniqu. Shift current is a steady-state photocurrent generated in non-centrosymmetric single crystals and has been considered to be one of the major origins of the bulk photovoltaic effect.

The mechanism. Current Science, The easiest illustration is the outstanding blue-shift of absorption, as well as the PL spectra of semiconductor nanoparticles with decreasing particle size, especially when the size is sufficiently small.

The wurtzite phase GaN dots have average dimensions of ~5 nm and their optical properties exhibit quantum. Contact resistance to a thin semiconductor layer.

Metal-Semiconductor Field Effect Transistors (MESFETs) Schottky diode with an interfacial layer Other unipolar junctions. The n-n + homojunction The n-n + heterojunction Currents across a n-n + heterojunction.

Currents through insulators. Fowler. The L-shaped wurtzite CGZS nanorods with a uniform spatial composition distribution are synthesized via a non-injection solution approach for the first time.

The successive incorporation of zinc and gallium ions into Cu 31 S 16 seeds leads to formation of Cu 31 S 16 –ZnS and Cu 31 S 16 –CGZS heteronanostructures and finally results in the. lattice. GaAs and InP are examples of “compound semiconductors”. Si, C, and Ge are examples of “elemental semiconductors”.

Not all compound semiconductors have the zinc blende lattice. For example, III-Nitrides (e.g GaN, AIN,InN) can also have the wurtzite lattice structure show below.

A GaAs lattice (zincblende lattice). We calculate the lattice thermal conductivity ($κ$) for cubic (zinc-blende) and hexagonal (wurtzite) phases for 8 semiconductors using {\\it ab initio} calculations and iteratively solving the Phonon Boltzmann Transport Equation, explaining the different behavior of the ratio $κ_{\\rm hex}/κ_{\\rm cub}$ between the two phases.

We show that this behavior. The crystal structure of CdSe core is determined by XRD and the fine peaks in absorption spectra. The XRD patterns of WZ- and ZB-CdSe core are shown in Fig. the WZ-CdSe diffraction pattern, the broad peak around 2θ=25° and the (1 0 3) peak at 2θ=° are the unique features of for the ZB-CdSe NCs, there are a sharp (1 1 1) peak at.

Most semiconductors have a diamond, zinc-blende wurtzite or rock-salt crystal structure. Elements and binary compounds, which average four valence electrons per atom, preferentially form tetrahedral bonds.

A tetrahedral lattice site in a compound AB is one in which each atom A is surrounded symmetrically by four nearest neighboring B atoms. Indeed, it is important to consider the confinement of both phonons and carriers in the design and modeling of novel semiconductor lasers such as the tunnel injection laser, quantum well intersubband lasers, and quantum dot lasers.

Herein we employed a first-principles method based on density functional theory to investigate the surface energy and growth kinetics of wurtzite nanoplatelets to elucidate why nanoplatelets exhibit a uniform thickness of eight monolayers.

We synthesized a series of wurtzite nanoplatelets (ZnSe, ZnS, ZnTe, and CdSe) with an atomically uniform thickness of eight. Neutral shallow impurities in semiconductors are very effective scatterers of thermal phonons at low temperatures.

Diamond [1] and zincblende crystals [2] have been widely investigated. In the present paper we calculated for the wurtzite-type semiconductors (CdS, CdSe, ZnO) the phonon relaxation rates due to elastic scattering by shallow acceptors. opment of multinary wurtzite-type oxide semiconductors.

2. β-LiGaO 2 Among the β-NaFeO 2 oxide semiconductors, β-LiGaO 2 is the best understood, as a β-LiGaO 2 single crystal was ﬁrst obtained in the s by Hoppe [43] and Remeika et al [44].properties of ZnO in wurtzite structure.

The mBJLDA potential not only provides better band gaps and also rea-sonably reproduces the reliable experimental ones for semiconductors and highly correlated electron system [31].

In FP-LAPW method, the basis set is obtained by dividing the unit cell into nonoverlapping spheres su- r.Persistent spin textures and currents in wurtzite nanowire-based quantum structures Michael Kammermeier, Adrian Seith, Paul Wenk, and John Schliemann .