Growth and Characterization of Low Temperature InP by Gas Source MBE

1991 ◽  
Vol 241 ◽  
Author(s):  
G. N. Maracas ◽  
K. T. Shiralagi ◽  
R. A. Puechner ◽  
F. Yu ◽  
K. T. Choi ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Deep Level ◽  
Level Structure ◽  
Buffer Layers ◽  
High Resistivity ◽  
Variable Range Hopping ◽  
Variable Range ◽  
Gas Source ◽  
Gas Source Mbe ◽  
Lt Gaas

The introduction of GaAs grown at low MBE growth temperatures has spurred considerable activity in attempts to understand conduction mechanisms and optical properties. In LT GaAs, the formation of microscopic As precipitates dominates the conductivity, producing electronic transport mainly by variable range hopping conduction. The resulting high resistivity and short carrier lifetimes have enabled the use of LT GaAs in FET buffer layers as well as in ultra-fast optical switches. An extension to AlInAs has also been performed and it was seen that variable range hopping is also present in the Asbased ternary.We report the optical and electronic properties of InP grown at low temperatures in a gas source MBE using dimeric phosphorus produced from cracked phosphine. The conductivity is higher than the equivalent GaAs LT material and does not have the same temperature dependence. The conditions under which growth occurs ie, substrate temperatures, V/ill ratios and annealing is explored. The structural properties, temperature dependence of the conductivity, deep level structure and the photoluminescence properties of the material are also investigated.

Variable Range Hopping Resistivity in La2-xSrxCuO4 Nanoparticles Evaluated by Four Point Probe Method

2020 ◽  
Vol 860 ◽  
pp. 142-147
Author(s):  
Suci Winarsih ◽  
Faisal Budiman ◽  
Hirofumi Tanaka ◽  
Tadashi Adachi ◽  
Takayuki Goto ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Thermal Activation ◽  
Resistivity Measurement ◽  
Probe Method ◽  
Charge Carriers ◽  
High Resistivity ◽  
Variable Range Hopping ◽  
Variable Range ◽  
Hopping Model ◽  
Variable Range Hopping Model

We report the results of the resistivity measurement on La2-xSrxCuO4 nanoparticles with x = 0, 0.05, and 0.20 evaluated by the four-point probe method. The high resistivity value shows the predominance of the inter-grain part. The temperature dependence of the conductivity can be analyzed by variable range hopping model showing the charge carriers are formed by thermal activation. There is no superconducting behavior that could be observed in La2-xSrxCuO4 nanoparticles with x = 0.05 and 0.20.

THE HOPPING CONDUCTION OF NEUTRON TRANSMUTED GERMANIUM

1994 ◽  
Vol 08 (07) ◽  
pp. 883-889 ◽  
Author(s):  
A.G. ZABRODSKII ◽  
A.G. ANDREEV
Keyword(s):  
Temperature Dependence ◽  
Nearest Neighbor ◽  
Hopping Conduction ◽  
Variable Range Hopping ◽  
Hopping Transport ◽  
Coulomb Gap ◽  
Variable Range ◽  
Neutron Transmutation ◽  
Mi Transition ◽  
Main Impurity

An investigation was made of a batch of samples of neutron transmutation-doped (NTD) Ge:Ga with the degree of compensation K=0.3 and the concentration of the main impurity (Ga) from N=3.6 · 1014cm−3 to Nc=2.5 · 1017cm−3, corresponding to the MI transition. The following were studied: the parameters of NTD Ge:Ga, the temperature dependence of hopping transport, the ɛ3 region of the nearest neighbor hopping (NNH), the saturation of NNH, variable range hopping (VRH) and the Coulomb gap.

LOCALIZATION EFFECT AND PSEUDOGAP IN PRASEODYMIUM DOPED Y1-zPrzBa2Cu3O7-δ SINGLE CRYSTALS

2012 ◽  
Vol 26 (25) ◽  
pp. 1250163 ◽  
Author(s):  
R. V. VOVK ◽  
Z. F. NAZYROV ◽  
I. L. GOULATIS ◽  
A. CHRONEOS
Keyword(s):  
Temperature Dependence ◽  
Single Crystals ◽  
Variable Range Hopping ◽  
Variable Range ◽  
Localization Effect ◽  
Transverse Conductivity

In this paper, we investigate the temperature dependence of the transverse conductivity in Y 1-z Pr z Ba 2 Cu 3 O 7-δ single crystals with different praseodymium concentrations. It is determined that the increase of the praseodymium concentration in Y 1-z Pr z Ba 2 Cu 3 O 7-δ leads to the enhancement of localization effects. This in turn results to the transition from the pseudo-gap regime to the variable-range-hopping regime.

Thermo-Electric Power of the Bi2Sr2Ca1-xCexCu2Oy System

1998 ◽  
Vol 12 (12) ◽  
pp. 475-488 ◽  
Author(s):  
D. R. Sita ◽  
R. Singh
Keyword(s):  
Temperature Dependence ◽  
Electric Power ◽  
Normal State ◽  
Narrow Band ◽  
Theoretical Models ◽  
Band Model ◽  
Variable Range Hopping ◽  
Thermo Electric ◽  
Variable Range ◽  
Narrow Band Model

The temperature dependence of thermo-electric power (TEP) of Bi 2 Sr 2 Ca 1-x Ce x Cu 2 O y samples with x upto 0.4 are reported in the temperature range 40–300 K. The normal state TEP data of the superconducting samples are discussed in view of some of the existing theoretical models in the literature, viz. two-band models, Nagaosa and Lee model and a phenomenological narrow band model. The transport in the semiconducting sample is found to be by variable-range-hopping mechanism.

Defect Studies in n-Type GaN Grown by Molecular Beam Epitaxy

1995 ◽  
Vol 378 ◽  
Author(s):  
W. Götz ◽  
D. B. Oberman ◽  
J. S. Harris
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Electron Cyclotron Resonance ◽  
Deep Level ◽  
Growth Parameters ◽  
Ecr Plasma ◽  
Gas Source ◽  
Deep Donor ◽  
Hall Effect Measurements ◽  
Gas Source Mbe

AbstractGaN thin films grown by molecular beam epitaxy (MBE) were characterized by Hall effect measurements in the temperature range from 80 K to 500 K and by photoluminescence spectroscopy (PL) at 2 K and at 300 K. These films were grown by MBE utilizing either electron cyclotron resonance (ECR) plasma activated nitrogen gas or thermally cracked hydrogen azide (HN3) as the source of chemically reactive nitrogen. The electrical properties of the GaN films grown by ECR plasma assisted MBE were found to vary with growth parameters, dominated either by shallow donors with activation energies (ΔE)in the range between 10 meV and 30 meV or deep donor levels (ΔE; > 500 meV). GaN grown by (HN3) gas-source MBE exhibited metallic conduction and electron mobilities <1 cm2/Vs. However, these films displayed sharp photoluminescence lines at 3.360 eV and 3.298 eV and no deep level related luminescence, whereas only broad deep level related emission was observed in the PL spectra of the ECR plasma assisted MBE grown GaN films.

Electrically Conducting Thin Films by Ion Implantation of Pyrolyzed Polyacrylonitrile

1988 ◽  
Vol 128 ◽  
Author(s):  
R. A. Basheer
Keyword(s):  
Ion Implantation ◽  
Temperature Dependence ◽  
Three Dimensional ◽  
Chemical Doping ◽  
Hopping Conduction ◽  
Variable Range Hopping ◽  
Specific Chemical ◽  
Variable Range ◽  
Heat Treated ◽  
Variable Range Hopping Conduction

ABSTRACTHeat treatment of polyacrylonitrile leads to products with semiconductor to metal like conductivities. The electrical properties of these materials are further modified by ion implantation. It is noted that the conductivity (∼10-7 (Ω cm)-1) of heat treated Polyacrylonitrile at 435°C (PAN435) increases upon ion implantation with As+, Kr+, Cl+ of F+ reaching a maximum value of 8.9 × 10-1 (Ω cm)-1 at as does of 5 × 1016 ion/cm2 and an energy of 200 KeV for the case of F+ implantation. On the other hand, ion implantation of the more conducting heat treated PAN at 750°C (PAN750) leads to a decrease in the electrical conductivity of the material. It is proposed that the conductivity modifications are primarily due to structural rearrangements induced by the energetic ions. Specific chemical doping contribution to conductivity is noted for halogen implantation in PAN435. The temperature dependence of conductivity of PAN heat treated at 750°C suggests a two path conduction, namely, a three dimensional variable range hopping conduction and a metallic conduction. After ion implantation, the conductivity-temperature dependence is interpreted in terms of a variable range hopping conduction mechanism.

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