scholarly journals Evidence of Intersubband Linewidth Narrowing Using Growth Interruption Technique

Photonics ◽  
2019 ◽  
Vol 6 (2) ◽  
pp. 38 ◽  
Author(s):  
Ngoc Tran ◽  
Giorgio Biasiol ◽  
Arnaud Jollivet ◽  
Alberto Bertocci ◽  
François Julien ◽  
...  
Keyword(s):  
Impurity Scattering ◽  
Undoped Sample ◽  
Interface Roughness ◽  
Threshold Intensity ◽  
Scattering Mechanism ◽  
Intersubband Transitions ◽  
Growth Interruption ◽  
Ionized Impurity Scattering ◽  
Interface Roughness Scattering ◽  
Coherent Emission

We report on the systematic study of two main scattering mechanisms on intersubband transitions, namely ionized impurity scattering and interface roughness scattering. The former mechanism has been investigated as a function of the dopants position within a multiple GaAs/AlGaAs quantum well structure and compared to the transition of an undoped sample. The study on the latter scattering mechanism has been conducted using the growth interruption technique. We report an improvement of the intersubband (ISB) transition linewidth up to 11% by interrupting growth at GaAs-on-AlGaAs interfaces. As a result, the lifetime of intersubband polaritons could be improved up to 9%. This leads to a reduction of 17% of the theoretical threshold intensity for polaritonic coherent emission. This work brings a useful contribution towards the realization of polariton-based devices.

The Effects of the Carrier Concentrations on the Hall Mobilities of ZnO:Al Thin Films Deposited by Magnetron Sputtering

2017 ◽  
Vol 727 ◽  
pp. 938-941
Author(s):  
Xiao Jing Wang ◽  
Yun Zhang
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Magnetron Sputtering ◽  
Carrier Concentration ◽  
Carrier Mobility ◽  
Impurity Scattering ◽  
Flexible Substrates ◽  
Boundary Scattering ◽  
Scattering Mechanism ◽  
Ionized Impurity Scattering

ZnO:Al thin films were deposited on flexible substrates by magnetron sputtering. The effects of the carrier concentrations on the hall mobilities of AZO films were investigated. When the carrier concentration was high (~1020/cm3), the hall mobility decreased with increase of the carrier concentration, showing obvious characteristics of ionized impurity scattering; moreover, the carrier mobility could be expressed to be-2.14/3 proportional of the carrier concentration by combining the results of simulation and experiments.simulation and experiment. When the carrier concentration was about a magnitude of 1019 cm-3, the carrier mobility is influenced by the carrier concentration and grain size, which means the carrier mobility was affected by both the grain boundary scattering and ionized purity scattering mechanism.

MAGNETORESISTANCE OF A SILICON MOSFET ON THE (111) SURFACE IN A PARALLEL MAGNETIC FIELD

2007 ◽  
Vol 21 (08n09) ◽  
pp. 1529-1534 ◽  
Author(s):  
A. GOLD ◽  
O. ANTONIE
Keyword(s):  
Magnetic Field ◽  
Electron Gas ◽  
Impurity Scattering ◽  
Interface Roughness ◽  
Zero Temperature ◽  
Parallel Magnetic Field ◽  
Interface Roughness Scattering ◽  
Dimensional Electron Gas ◽  
Passivated Silicon ◽  
Theoretical Results

In comparison with silicon (100) we argue that the silicon (111) surface is a surface with higher mobility and stronger Coulomb interaction effects. For the resistance of the two-dimensional electron gas we discuss the effects of a magnetic field parallel to the surface: for zero temperature we present theoretical results for the magnetoresistance of an electron gas at the surface of silicon (111) with a six-fold valley degeneracy. Impurity scattering and interface roughness scattering are taken into account. A recent study of a hydrogen-passivated silicon (111) surface showed a mobility proportional to the electron density. We present, using a model for neutral impurities, predictions for the magnetoresistance of this sample in a parallel magnetic field.

scholarly journals Temperature and electric field dependences of the mobility of electrons in vertical transport in GaAs/Ga1−y AlyAs barrier structures containing quantum wells

Open Physics ◽  
2008 ◽  
Vol 6 (3) ◽  
Author(s):  
Safi Altunöz ◽  
Hüseyin Çelik ◽  
Mehmet Cankurtaran
Keyword(s):  
Quantum Wells ◽  
Applied Voltage ◽  
Phonon Scattering ◽  
Impurity Scattering ◽  
Vertical Transport ◽  
Interface Roughness ◽  
Polar Optical Phonon ◽  
Optical Phonon Scattering ◽  
Interface Roughness Scattering ◽  
The Difference

AbstractThe mobility of electrons in vertical transport in GaAs/Ga1−y AlyAs barrier structures was investigated using geometric magnetoresistance measurements in the dark. The samples studied had Ga1−y AlyAs (0 ≤ y ≤ 0:26) linearly graded barriers between the n+-GaAs contacts and the Ga0:74Al0:26As central barrier, which contain N w (=0, 2, 4, 7 and 10) n-doped GaAs quantum wells. The mobility was determined as functions of (i) temperature (80–290 K) at low applied voltage (0.01–0.1 V) and (ii) applied voltage (0.005–1.6 V) at selected temperatures in the range 3.5–290 K. The experimental results for the temperature dependence of low-field mobility suggest that space-charge scattering is dominant in the samples with N w=0 and 2, whereas ionized impurity scattering is dominant in the samples with N w=4, 7 and 10. The effect of polar optical phonon scattering on the mobility becomes significant in all barrier structures at temperatures above about 200 K. The difference between the measured mobility and the calculated total mobility in the samples with N w=4, 7 and 10, observed above 200 K, is attributed to the reflection of electrons from well-barrier interfaces in the quantum wells and interface roughness scattering. The rapid decrease of mobility with applied voltage at high voltages is explained by intervalley scattering of hot electrons.

scholarly journals Manipulation of ionized impurity scattering for achieving high thermoelectric performance in n-type Mg3Sb2-based materials

2017 ◽  
Vol 114 (40) ◽  
pp. 10548-10553 ◽  
Author(s):  
Jun Mao ◽  
Jing Shuai ◽  
Shaowei Song ◽  
Yixuan Wu ◽  
Rebecca Dally ◽  
...  
Keyword(s):  
Power Factor ◽  
Carrier Mobility ◽  
Phonon Scattering ◽  
Impurity Scattering ◽  
Substantial Improvement ◽  
Thermoelectric Performance ◽  
Scattering Mechanism ◽  
Carrier Scattering ◽  
Ionized Impurity Scattering ◽  
Higher Carrier Mobility

Achieving higher carrier mobility plays a pivotal role for obtaining potentially high thermoelectric performance. In principle, the carrier mobility is governed by the band structure as well as by the carrier scattering mechanism. Here, we demonstrate that by manipulating the carrier scattering mechanism in n-type Mg3Sb2-based materials, a substantial improvement in carrier mobility, and hence the power factor, can be achieved. In this work, Fe, Co, Hf, and Ta are doped on the Mg site of Mg3.2Sb1.5Bi0.49Te0.01, where the ionized impurity scattering crosses over to mixed ionized impurity and acoustic phonon scattering. A significant improvement in Hall mobility from ∼16 to ∼81 cm2⋅V−1⋅s−1 is obtained, thus leading to a notably enhanced power factor of ∼13 μW⋅cm−1⋅K−2 from ∼5 μW⋅cm−1⋅K−2. A simultaneous reduction in thermal conductivity is also achieved. Collectively, a figure of merit (ZT) of ∼1.7 is obtained at 773 K in Mg3.1Co0.1Sb1.5Bi0.49Te0.01. The concept of manipulating the carrier scattering mechanism to improve the mobility should also be applicable to other material systems.

Effects of ionized impurity and interface roughness scatterings on the electron mobility in InAs/GaSb type II superlattices at low temperatures

2016 ◽  
Vol 30 (32n33) ◽  
pp. 1650384
Author(s):  
S. Safa ◽  
A. Asgari
Keyword(s):  
Electron Mobility ◽  
Low Temperatures ◽  
Structural Parameters ◽  
Impurity Scattering ◽  
Interface Roughness ◽  
Type Ii ◽  
Type Ii Superlattices ◽  
Interface Roughness Scattering ◽  
Different Temperatures ◽  
Scattering Rates

The in-plane electron mobility has been calculated in InAs/GaSb type-II superlattices (SLs) at low temperatures. The interface roughness scattering and ionized impurity scattering are investigated as the dominant scattering mechanisms in limiting the electron transport at low temperatures. For this purpose, the band structures and wave functions of electrons in such SLs are calculated by solving the K.P Hamiltonian using the numerical Finite Difference method. The scattering rates have been obtained for different temperatures and structural parameters. We show that the scattering rates are high in thin-layer SLs and the mobility rises as the temperature increases in low-temperature regime.

scholarly journals Comparison of THz-QCL Designs Supporting Clean N-Level Systems

Photonics ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 248
Author(s):  
Nathalie Lander Gower ◽  
Silvia Piperno ◽  
Asaf Albo
Keyword(s):  
Room Temperature ◽  
Impurity Scattering ◽  
Interface Roughness ◽  
Future Research ◽  
Quantum Cascade ◽  
Thermally Activated ◽  
N Level ◽  
Temperature Performance ◽  
Ionized Impurity Scattering ◽  
Well Design

Three different Terahertz quantum-cascade-laser designs supporting clean n-level systems were analyzed using nonequilibrium Green’s functions. In clean n-level systems, most of the electrons occupy the active laser levels, with thermally activated leakage channels being suppressed almost entirely up to room temperature. Simulations of the three designs, namely a resonant phonon design, a two-well design, and a split-well direct-phonon design were investigated. The results from the simulations indicated that the two-well design would perform best overall, in terms of variations in current density, interface roughness, and ionized impurity scattering. We conclude that future research aiming to improve the temperature performance of such laser designs should be based on a two-well design.

Hydrodynamic Simulation of Drift Mobility in N-Hg0.8Cd0.2Te

2011 ◽  
Vol 312-315 ◽  
pp. 122-126
Author(s):  
Mebarka Daoudi ◽  
Abderrahmane Belghachi ◽  
Luca Varani ◽  
Christophe Palermo
Keyword(s):  
Experimental Data ◽  
Electric Field ◽  
Dominant Role ◽  
Impurity Scattering ◽  
Drift Mobility ◽  
Scattering Mechanism ◽  
Hydrodynamic Simulation ◽  
Monte Carlo Calculations ◽  
Ionized Impurity Scattering ◽  
Good Agreement

In this paper, the transport properties of Hg0.8Cd0.2Te have been investigated at 77 K using the hydrodynamic model. We remarked that ionized impurity scattering mechanism plays a dominant role in this material at low electric field. The drift velocity, mean energy and drift mobility are determined as functions of the electric field strength. Comparison is made with Monte Carlo calculations and experimental results. The obtained velocity-field curve is in good agreement with reported experimental data.

The effect of interface roughness scattering and background impurity scattering on the thermopower of a 2DEG in a Si MOSFET

1990 ◽  
Vol 2 (51) ◽  
pp. 10401-10410 ◽  
Author(s):  
V K Karavolas ◽  
M J Smith ◽  
T M Fromhold ◽  
P N Butcher ◽  
B G Mulimani ◽  
...  
Keyword(s):  
Impurity Scattering ◽  
Interface Roughness ◽  
Background Impurity ◽  
Interface Roughness Scattering
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