DENSITY OF STATES AND CHARGE DISTRIBUTION IN LIGHTLY DOPED AND COMPENSATED QUANTUM WELL

1989 ◽  
Vol 03 (11) ◽  
pp. 815-819
Author(s):  
E.A. DE ANDRADA E SILVA ◽  
I.C. DA CUNHA LIMA
Keyword(s):  
Quantum Well ◽  
Charge Distribution ◽  
Density Of States ◽  
Impurity Band ◽  
Band Model ◽  
Two Dimensional ◽  
Bohr Radius ◽  
Coulomb Gap ◽  
Bulk Semiconductors ◽  
Infra Red

In this letter we use a Semi-Classical Impurity Band Model and obtain by Monte Carlo simulation the density of states (DOS) and the impurity charge distribution inside a quantum well (QW) of Ga 1−x Al x As/GaAs . We show the existence of a Coulomb gap as has been observed in bulk semiconductors. The DOS is not very sensitive to the QW width close to the Coulomb gap, at least in the range from 1 to 4 times the Bohr radius, and shows a behavior D(E)∝|E−EF| which indicates a two-dimensional signature. We show that the neutral donors concentrate in the center of the well according to a distribution whose width and decay rate depend on the compensation and impurity concentration respectively. Those effects are expected to be observed by infra-red absorption experiments and useful in device diagnosis.

Coulomb Gap in the Tunneling Density of States of Two-Dimensional Electron Liquid in a Strong Magnetic Field

1994 ◽  
Vol 08 (07) ◽  
pp. 913-921
Author(s):  
A.L. Efros ◽  
F.G. Pikus
Keyword(s):  
Magnetic Field ◽  
Strong Magnetic Field ◽  
Density Of States ◽  
Tunneling Current ◽  
Double Quantum ◽  
Two Dimensional ◽  
Classical Electron ◽  
Coulomb Gap ◽  
Double Quantum Well ◽  
Single Well

A model of a classical electron liquid without external disorder is applied to two-dimensional electrons in a strong magnetic field. Computer modeling gives a quantitative explanation for the recently observed gap in the tunneling current of a double quantum well structure. We find that both the Coulomb gap in the single-well density of states and the correlation of electron motion in the two wells are responsible for the tunneling gap. We show that the classical liquid model provides an accurate description of the low temperature compressibility obtained from magnetocapacitance experiment.

scholarly journals Evaluation of Energy and Density of States of Two Dimensional Quantum Structure (Quantum Well)

2018 ◽  
pp. 1-6
Author(s):  
J. Ilouno ◽  
I. J. Audu ◽  
M. Y. Mafuyai ◽  
N. Okpara
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Density Of States ◽  
High Energy ◽  
Two Dimensional ◽  
Density Of State ◽  
Quantum Structure ◽  
Electrochromic Devices ◽  
High Energy Level ◽  
System Designs

Quantum structures (e.g. quantum wells) are a critical part of optical system designs (lasers, modulators, switches etc.). In the quantum well, the motion of the particle is quantized in one direction while the particle moves freely in other two directions. The density of state of the quantum structure is the possible number of state an excited electron can occupy per unit volume. The density of state depends on the energy at which the electron moves when excited. In this paper, the energy and density of states of two-dimensional quantum structure (quantum well) were calculated. The results obtained revealed the density of state increases with the energy but exhibited maximum and minimum peaks. Maximum peaks occurred at 4 eV and 7.5 eV while the minimum peaks occurred at 5 eV and 8 eV. These show that energy of state for quantum wells neither varies linearly nor exponentially with a density of state because of high energy level. The findings are in agreement with published literature. Some applications of quantum wells include: bioconjugates, solar cells, photovoltaic, photo and electrochromic devices etc.

HEAVILY DOPED HARMONIC CONFINED QUANTUM WIRES

1992 ◽  
Vol 06 (29) ◽  
pp. 1881-1885
Author(s):  
I.C. DA CUNHA LIMA ◽  
A. FERREIRA DA SILVA
Keyword(s):  
Binding Energy ◽  
Quantum Well ◽  
Density Of States ◽  
Gate Voltage ◽  
Quantum Wires ◽  
Impurity Band ◽  
Semiconductor Heterostructures ◽  
One Dimensional ◽  
Impurity Density ◽  
Heavily Doped

Quasi-one-dimensional channels have already been fabricated by holographic lithography on semiconductor heterostructures. We study the formation of an impurity band for shallow donors located inside the channels assuming they have been created by applying a modulated gate voltage in a quantum well of AlxGa1−xAs−GaAs. We calculate the changes in the impurity density of states as a function of the gate voltage. It is shown that the increase of the applied gate voltage leads to higher binding energy and larger impurity bandwidth.

Absence of a Coulomb gap in a two-dimensional impurity band

1986 ◽  
Vol 33 (2) ◽  
pp. 1499-1502 ◽  
Author(s):  
G. Timp ◽  
A. B. Fowler ◽  
A. Hartstein ◽  
P. N. Butcher
Keyword(s):  
Impurity Band ◽  
Two Dimensional ◽  
Coulomb Gap

scholarly journals Manipulation of hot carrier cooling dynamics in two-dimensional Dion–Jacobson hybrid perovskites via Rashba band splitting

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jun Yin ◽  
Rounak Naphade ◽  
Partha Maity ◽  
Luis Gutiérrez-Arzaluz ◽  
Dhaifallah Almalawi ◽  
...  
Keyword(s):  
Transient Absorption ◽  
Phonon Scattering ◽  
Transient Absorption Spectroscopy ◽  
Band Model ◽  
Two Dimensional ◽  
Spintronic Devices ◽  
Hot Carrier ◽  
Band Splitting ◽  
Perovskite Materials ◽  
Spin Polarized

AbstractHot-carrier cooling processes of perovskite materials are typically described by a single parabolic band model that includes the effects of carrier-phonon scattering, hot phonon bottleneck, and Auger heating. However, little is known (if anything) about the cooling processes in which the spin-degenerate parabolic band splits into two spin-polarized bands, i.e., the Rashba band splitting effect. Here, we investigated the hot-carrier cooling processes for two slightly different compositions of two-dimensional Dion–Jacobson hybrid perovskites, namely, (3AMP)PbI4 and (4AMP)PbI4 (3AMP = 3-(aminomethyl)piperidinium; 4AMP = 4-(aminomethyl)piperidinium), using a combination of ultrafast transient absorption spectroscopy and first-principles calculations. In (4AMP)PbI4, upon Rashba band splitting, the spin-dependent scattering of hot electrons is responsible for accelerating hot-carrier cooling at longer delays. Importantly, the hot-carrier cooling of (4AMP)PbI4 can be extended by manipulating the spin state of the hot carriers. Our findings suggest a new approach for prolonging hot-carrier cooling in hybrid perovskites, which is conducive to further improving the performance of hot-carrier-based optoelectronic and spintronic devices.

IONIZATION ENERGY AND IMPURITY BAND CONDUCTION OF SHALLOW DONORS IN n-GALLIUM ARSENIDE

1967 ◽  
Vol 45 (1) ◽  
pp. 119-126 ◽  
Author(s):  
J. Basinski ◽  
R. Olivier
Keyword(s):  
Ionization Energy ◽  
Impurity Band ◽  
Shallow Donor ◽  
Band Model ◽  
A Value ◽  
Transition Concentration ◽  
Temperature Electron ◽  
Two Band Model ◽  
Band Conduction ◽  
Made In

Hall effect and resistivity measurements have been made in the temperature range 4.2–360 °K on several samples of n-type GaAs grown under oxygen atmosphere and without any other intentional dopings. The principal shallow donor in this material is considered to be Si. All samples exhibited impurity-band conduction at low temperature. Electron concentrations in the conduction band were calculated, using a two-band model, and then fitted to the usual equation expressing charge neutrality. A value of 2.3 × 10−3 eV was obtained for the ionization energy of the donors, for donor concentration ranging from 5 × 1015 cm−3 to 2 × 1016 cm−3. The conduction in the impurity band was of the hopping type for these concentrations. A value of 3.5 × 1016 cm−3 was obtained for the critical transition concentration of the impurity-band conduction to the metallic type.

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