Defects in Superlattices Under Pressure

1986 ◽  
Vol 77 ◽  
Author(s):  
Run-Di Hong ◽  
David W. Jenkins ◽  
S. Y. Ren ◽  
John D. Dow
Keyword(s):  
Hydrostatic Pressure ◽  
Quantum Well ◽  
Phase Boundary ◽  
Band Gap ◽  
Phase Diagrams ◽  
Conduction Band ◽  
Deep Level ◽  
Theoretical Calculations ◽  
Deep Trap ◽  
Quantum Well Width

ABSTRACTWe report theoretical calculations of deep levels in GaAs/AlxGa1−xAs superlattices under hydrostatic pressure. We predict phase diagrams for DX centers: for a given composition x there is a function p(a), which relates pressure p and GaAs quantum-well width a, and defines a phase boundary between two regions: one in which DX is a deep trap in the fundamental band gap and another in which the DX deep level lies in the conduction band.

Deep Levels in Superlattices

1989 ◽  
Vol 163 ◽  
Author(s):  
John D. Dow ◽  
Shang Yuan Ren ◽  
Jun Shen ◽  
Min-Hsiung Tsai
Keyword(s):  
Band Gap ◽  
Quantum Confinement ◽  
Deep Level ◽  
Energy Levels ◽  
Deep Trap ◽  
Shallow Donor ◽  
Deep Levels ◽  
Band Gap Engineering ◽  
Substitutional Impurities ◽  
Superlattice Period

AbstractThe physics of deep levels in semiconductors is reviewed, with emphasis on the fact that all substitutional impurities produce deep levels - some of which may not lie within the fundamental band gap. The character of a dopant changes when one of the deep levels moves into or out of the fundamental gap in response to a perturbation such as pressure or change of host composition. For example, Si on a Ga site in GaAs is a shallow donor, but becomes a deep trap for x>0.3 in AℓxGa1-xAs. Such shallow-deep transitions can be induced in superlattices by changing the period-widths and quantum confinement. A good rule of thumb for deep levels in superlattices is that the energy levels with respect to vacuum are relatively insensitive (on a >0.1 eV scale) to superlattice period-widths, but that the band edges of the superlattices are sensitive to changes of period. Hence the deep level positions relative to the band edges are sensitive to the period-widths, and shallow-deep transitions can be induced by band-gap engineering the superlattice periods.

EFFECT OF Γ-X CROSSOVER ON THE DONOR BINDING ENERGY IN A QUANTUM WELL

2005 ◽  
Vol 19 (25) ◽  
pp. 3861-3868 ◽  
Author(s):  
P. NITHIANANTHI ◽  
K. JAYAKUMAR
Keyword(s):  
Hydrostatic Pressure ◽  
Binding Energy ◽  
Quantum Well ◽  
Excited States ◽  
Conduction Band ◽  
Ground State ◽  
External Hydrostatic Pressure ◽  
Donor Binding Energy ◽  
Dielectric Screening

The effect of Γ-X crossover due to the external hydrostatic pressure on the ground state donor binding energy as well as for some low lying excited states for a Quantum well has been investigated by considering the non-parabolicity of the conduction band and pressure dependent spatial dielectric screening. It is observed that the effect of Γ-X crossover is predominant for ground state than for low lying excited states.

Hydrogen Diffusion in n-GaAs:Si Under Hydrostatic Pressure

1995 ◽  
Vol 378 ◽  
Author(s):  
B. Machayekhi ◽  
J. Chevallier ◽  
B. Theys ◽  
J. M. Besson ◽  
G. Weill ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Band Gap ◽  
Conduction Band ◽  
Hydrogen Diffusion ◽  
Diffusion Profile ◽  
Acceptor Level ◽  
Hydrogen Acceptor ◽  
Diffusion Depth ◽  
Sims Analysis

ABSTRACTIt has recently been shown that deuterium diffusion experiments can provide information on the deepening of the hydrogen acceptor level in the band gap of AlxGa1-xAs alloys with increasing x. In the present work, we report on the influence of hydrostatic pressure on deuterium diffusion in n-GaAs:Si. SIMS analysis reveals that the deuterium profiles in n-GaAs:Si are sensitive to hydrostatic pressure: the diffusion depth decreases and a plateau appears in the diffusion profile as the pressure is applied. The results are interpreted in terms of an increasing amount of the H- species as pressure is applied. This increase is mainly attributed to a deepening of the H acceptor level with respect to the bottom of the Γ conduction band of GaAs. Qualitatively, this effect is similar to the deepening of the H acceptor level in AlxGa1-xAs alloys as x increases.

Lattice and electronic effects in rutile TiO2 containing charged oxygen defects from ab initio calculations

2009 ◽  
Vol 1160 ◽  
Author(s):  
Seong-Geon Park ◽  
Blanka Magyari-Köpe ◽  
Yoshio Nishi
Keyword(s):  
Oxygen Vacancy ◽  
Band Gap ◽  
Conduction Band ◽  
Density Functional ◽  
Deep Level ◽  
Vacancy Defect ◽  
Conduction Band Minimum ◽  
Electronic Effects ◽  
Atomic Relaxation ◽  
Gap States

AbstractWe performed first-principle simulation for the study of oxygen vacancy defect in rutile TiO2 based on density functional theory. The effects of a vacancy on the electronic structure of rutile TiO2 were studied. Here we have employed neutral and charged oxygen vacancy in the supercell to address the resistance switching mechanism. Neutral vacancy induces the band gap states at deep level, ∼0.7 eV below the conduction band minimum, which is occupied by highly localized electrons. The calculation results of positively charged oxygen vacancy show that larger atomic relaxation surrounding oxygen vacancy results in the stretching of Ti-O bond around vacancy, thus band gap states are formed near the conduction band minimum.

scholarly journals Dimension control of in situ fabricated CsPbClBr2 nanocrystal films toward efficient blue light-emitting diodes

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Chenhui Wang ◽  
Dengbao Han ◽  
Junhui Wang ◽  
Yingguo Yang ◽  
Xinyue Liu ◽  
...  
Keyword(s):  
Quantum Well ◽  
Light Emitting Diodes ◽  
Blue Emission ◽  
Light Emitting ◽  
Mixed Ligands ◽  
Dimension Control ◽  
Nanocrystal Films ◽  
Width Distribution ◽  
Quantum Well Width

AbstractIn the field of perovskite light-emitting diodes (PeLEDs), the performance of blue emissive electroluminescence devices lags behind the other counterparts due to the lack of fabrication methodology. Herein, we demonstrate the in situ fabrication of CsPbClBr2 nanocrystal films by using mixed ligands of 2-phenylethanamine bromide (PEABr) and 3,3-diphenylpropylamine bromide (DPPABr). PEABr dominates the formation of quasi-two-dimensional perovskites with small-n domains, while DPPABr induces the formation of large-n domains. Strong blue emission at 470 nm with a photoluminescence quantum yield up to 60% was obtained by mixing the two ligands due to the formation of a narrower quantum-well width distribution. Based on such films, efficient blue PeLEDs with a maximum external quantum efficiency of 8.8% were achieved at 473 nm. Furthermore, we illustrate that the use of dual-ligand with respective tendency of forming small-n and large-n domains is a versatile strategy to achieve narrow quantum-well width distribution for photoluminescence enhancement.

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