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.

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.

Position of the Hydrogen Acceptor Level in n-GaAs:Si and n-AlGaAs:Si Deduced from Hydrogen Diffusion Modelling

1993 ◽  
Vol 143-147 ◽  
pp. 951-956 ◽  
Author(s):  
B. Machayekhi ◽  
R. Rahbi ◽  
B. Theys ◽  
M. Miloche ◽  
Jacques Chevallier
Keyword(s):  
Hydrogen Diffusion ◽  
Acceptor Level ◽  
Hydrogen Acceptor ◽  
Diffusion Modelling

From the Kohn–Sham band gap to the fundamental gap in solids. An integer electron approach

2017 ◽  
Vol 19 (24) ◽  
pp. 15639-15656 ◽  
Author(s):  
E. J. Baerends
Keyword(s):  
Band Gap ◽  
Conduction Band ◽  
Electron Crystal

The upshift Δ of the level at the bottom of the conduction band (the LUMO) from the neutral N-electron crystal to the negative N + 1 system, and therefore the fundamental gap εLUMO(N + 1) − εHOMO(N) = I − A, can be calculated simply and cheaply from the response part of vxc.

scholarly journals Effect of Yb Concentration on the Structural, Magnetic and Optoelectronic Properties of Yb Doped ZnO: First Principles Calculation

2021 ◽  
Author(s):  
Mohamed Achehboune ◽  
Mohammed Khenfouch ◽  
Issam Boukhoubza ◽  
Issam Derkaoui ◽  
Bakang Moses Mothudi ◽  
...  
Keyword(s):  
Band Gap ◽  
Conduction Band ◽  
Density Functional ◽  
Blue Shift ◽  
First Principles Calculation ◽  
Theoretical Research ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Doped Zno ◽  
Good Agreement

Abstract Density functional theory-based investigation of the electronic, magnetic, and optical characteristics in pure and ytterbium (Yb) doped ZnO has been carried out by the plane-wave pseudopotential technique with generalized gradient approximation. The calculated lattice parameters and band gap of pure ZnO are in good agreement with the experimental results. The energy band-gap increases with the increase of Yb concentration. The Fermi level moves upward into the conduction band after doping with Yb, which shows the properties of an n-type se miconductor. New defects were created in the band-gap near the conduction band attributed to the Yb-4f states. The magnetic properties of ZnO were found to be affected by Yb doping; ferromagnetic property was observed for 4.17% Yb due to spin polarization of Yb-4f electrons. The calculated optical properties imply that Yb doped causes a blue shift of the absorption peaks, significantly enhances the absorption of the visible light, and the blue shift of the reflectivity spectrum was observed. Besides, a better transmittance of approximately 88% was observed for 4.17% Yb doped ZnO system. The refractive index and the extinction coefficient were observed to decrease as the Yb dopant concentration increased. As a result, we believe that our findings will be useful in understanding the doping impact in ZnO and will motivate further theoretical research.

Effect of hydrostatic pressure on the fragmented conduction band structure of dilute Ga(AsN) alloys

2005 ◽  
Vol 72 (4) ◽  
Author(s):  
J. Endicott ◽  
A. Patanè ◽  
D. Maude ◽  
L. Eaves ◽  
M. Hopkinson ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Band Structure ◽  
Conduction Band ◽  
Effect Of Hydrostatic Pressure

EL2-Induced Upconversion Luminescence In GaAs

1996 ◽  
Vol 442 ◽  
Author(s):  
V. Alex ◽  
T. Iino
Keyword(s):  
Band Gap ◽  
Upconversion Luminescence ◽  
Hot Electrons ◽  
Complete Disappearance ◽  
Acceptor Level ◽  
Acceptor Pair ◽  
Step Process ◽  
Regeneration Mechanism ◽  
Donor Acceptor ◽  
Donor Acceptor Pair

AbstractNear band gap luminescence in bulk-grown semi-insulating GaAs is excited in a two step process via the EL2 defect. While the conventionally excited photoluminescence of our samples is dominated by conduction band to acceptor transitions, the upconversion process selectively excites donor acceptor pair transitions. Illumination near the maximum of the EL2- photoquenching band at 1064 nm leads to a complete disappearance of the so called upconversion photoluminescence (UPL). Excitation with light of shorter wavelengths however only partially quenches the UPL. Excitation between 850nm and 900nm completely regenerates the UPL. The characteristic photorecovery transients of the UPL are described by the EL2 regeneration mechanism via the population of the acceptor level of the metastable EL2 by hot electrons. The recovery of the EL2 by simultaneous illumination with above and below band gap light enables the observation of UPL at wavelengths, where the EL2-defect would otherwise be rapidly quenched. Under these conditions we observe a remarkable increase of the UPL-efficiency.

Study of Band Alignment at CBD-CdS/Cu(In1-xGax)Se2 (x = 0.2 - 1.0) Interfaces by Photoemission and Inverse Photoemission Spectroscopy

2007 ◽  
Vol 1012 ◽  
Author(s):  
Shimpei Teshima ◽  
Hirotake Kashiwabara ◽  
Keimei Masamoto ◽  
Kazuya Kikunaga ◽  
Kazunori Takeshita ◽  
...  
Keyword(s):  
Band Gap ◽  
Conduction Band ◽  
Valence Band Maximum ◽  
Band Gap Energy ◽  
Band Alignment ◽  
Photoemission Spectroscopy ◽  
Gap Energy ◽  
Conduction Band Offset ◽  
Inverse Photoemission ◽  
Inverse Photoemission Spectroscopy

AbstractDependence of band alignments at interfaces between CdS by chemical bath deposition and Cu(In1-xGax)Se2 by conventional 3-stage co-evaporation on Ga substitution ratio x from 0.2 to 1.0 has been systematically studied by means of photoemission spectroscopy (PES) and inverse photoemission spectroscopy (IPES). For the specimens of the In-rich CIGS, conduction band minimum (CBM) by CIGS was lower than that of CdS. Conduction band offset of them was positive about +0.3 ~ +0.4 eV. Almost flat conduction band alignment was realized at x = 0.4 ~ 0.5. On the other hand, at the interfaces over the Ga-rich CIGS, CBM of CIGS was higher than that of CdS, and CBO became negative. The present study reveals that the decrease of CBO with a rise of x presents over the wide rage of x, which results in the sign change of CBO around 0.4 ~ 0.45. In the Ga-rich interfaces, the minimum of band gap energy, which corresponded to energy spacing between CBM of CdS and valence band maximum of CIGS, was almost identical against the change of band gap energy of CIGS. Additionally, local accumulation of oxygen related impurities was observed at the Ga-rich samples, which might cause the local rise of band edges in central region of the interface.

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