First Microscopic Observation of Cadmium-Hydrogen Pairs in GaN

1996 ◽  
Vol 449 ◽  
Author(s):  
A. Burchard ◽  
M. Deicher ◽  
D. Forkel-Wirth ◽  
E. E. Haller ◽  
R. Magerle ◽  
...  
Keyword(s):  
Angular Correlation ◽  
Microscopic Observation ◽  
Correlation Spectroscopy ◽  
Low Energy ◽  
Hydrogen Atoms

ABSTRACTThe formation and properties of acceptor-hydrogen pairs in GaN have been studied using radioactive 111mCd acceptors and the perturbed γγ angular correlation spectroscopy (PAC). After H-loading by low energy implantation (100 eV) at temperatures between 295 K and 473 K, the formation of two Cd-H complexes involving about 30% of the Cd-acceptors is observed. The complexes have been identified as single hydrogen atoms bound to the Cd acceptor in two different configurations. The dissociation enthalpies of these configurations have been determined as 1.1(1) eV and 1.8(1) eV, respectively.

Defects in CdS: In detected by perturbed angular correlation spectroscopy (PAC)

1991 ◽  
Vol 50 (1-4) ◽  
pp. 159-164 ◽  
Author(s):  
R. Magerle ◽  
M. Deicher ◽  
U. Desnica ◽  
R. Keller ◽  
W. Pfeiffer ◽  
...  
Keyword(s):  
Angular Correlation ◽  
Perturbed Angular Correlation ◽  
Correlation Spectroscopy ◽  
Perturbed Angular Correlation Spectroscopy

Influence of low-energy electron beam irradiation on defects in activated Mg-doped GaN

2002 ◽  
Vol 744 ◽  
Author(s):  
O. Gelhausen ◽  
M. R. Phillips ◽  
H. N. Klein ◽  
E. M. Goldys
Keyword(s):  
Electron Beam ◽  
Electron Beam Irradiation ◽  
Low Energy ◽  
Energy Electron ◽  
Beam Irradiation ◽  
Hydrogen Atoms ◽  
Acceptor Pair ◽  
Low Energy Electron ◽  
The Impact ◽  
Mg Doped

ABSTRACTCL spectroscopy studies at varying temperatures and excitation power densities as well as depth-resolved CL imaging were conducted to investigate the impact of low energy electron beam irradiation (LEEBI) on native defects and residual impurities in metal-organic vapor phase epitaxy (MOVPE) grown Mg-doped p-type GaN. Due to the dissociation of (Mg-H)0 complexes, LEEBI significantly increases the (e,Mg0) emission (3.26 eV) at 300 K and substantially decreases the H-Mg donor-acceptor-pair (DAP) emission (3.27 eV) at 80 K. In-plane and depth-resolved CL imaging indicates that hydrogen dissociation results from electron-hole recombination at H-defect complexes rather than heating by the electron beam. The dissociated hydrogen atoms associate with nitrogen vacancies, forming a deeper donor, i.e. a (H-VN) complex. The corresponding deeper DAP emission with Mg centered at 3.1 eV is clearly observed between 160 and 220 K. Moreover, a broad yellow luminescence (YL) band centered at 2.2 eV is observed in MOVPE-grown Mg-doped GaN after LEEBI-treatment. It is suggested that a combination of LEEBI-induced Fermi-level downshift due to Mg-acceptor activation and simultaneous dissociation of gallium vacancy-impurity complexes, i.e. (VGa-H), is responsible for the observed YL.

Electron screening in low energy scattering of muonic hydrogen on hydrogen atoms

1986 ◽  
Vol 4 (2) ◽  
pp. 153-160 ◽  
Author(s):  
A. Adamczak ◽  
V. S. Melezhik ◽  
L. I. Menshikov
Keyword(s):  
Muonic Hydrogen ◽  
Low Energy ◽  
Electron Screening ◽  
Hydrogen Atoms ◽  
Energy Scattering

scholarly journals Excitation and charge transfer in low-energy hydrogen atom collisions with neutral carbon and nitrogen

2019 ◽  
Vol 625 ◽  
pp. A78 ◽  
Author(s):  
A. M. Amarsi ◽  
P. S. Barklem
Keyword(s):  
Charge Transfer ◽  
Neutral Hydrogen ◽  
Stellar Atmospheres ◽  
Low Energy ◽  
Rate Coefficients ◽  
Collision Dynamics ◽  
Hydrogen Atoms ◽  
Stellar Spectra ◽  
Zero Rate ◽  
Excitation Processes

Low-energy inelastic collisions with neutral hydrogen atoms are important processes in stellar atmospheres, and a persistent source of uncertainty in non-LTE modelling of stellar spectra. We have calculated and studied excitation and charge transfer of C I and of N I due to such collisions. We used a previously presented method that is based on an asymptotic two-electron linear combination of atomic orbitals (LCAO) model of ionic-covalent interactions for the adiabatic potential energies, combined with the multichannel Landau-Zener model for the collision dynamics. We find that charge transfer processes typically lead to much larger rate coefficients than excitation processes do, consistent with studies of other atomic species. Two-electron processes were considered and lead to non-zero rate coefficients that can potentially impact statistical equilibrium calculations. However, they were included in the model in an approximate way, via an estimate for the two-electron coupling that was presented earlier in the literature: the validity of these data should be checked in a future work.

scholarly journals Perturbed Angular Correlation Studies in SrTiO3 Single Crystals

2000 ◽  
Vol 55 (1-2) ◽  
pp. 237-241
Author(s):  
P. de la Presa ◽  
K. P. Lieb ◽  
M. Uhrmacher ◽  
L. Ziegeler
Keyword(s):  
Angular Correlation ◽  
Perturbed Angular Correlation ◽  
Hyperfine Interactions ◽  
Correlation Spectroscopy ◽  
Quadrupole Frequency ◽  
Perturbed Angular Correlation Spectroscopy ◽  
Temperature Range ◽  
Field Gradients ◽  
Electronic Defects ◽  
Asymmetry Parameters

The quadrupole hyperfine interactions of 111Cd/111 In probe nuclei in single-crystalline SrTiO3 perovskite samples were investigated using Perturbed Angular Correlation spectroscopy. Three electric field gradients were detected and their fractions and hyperfine parameters were measured in the temperature range from 26 to 700 K. The fraction f0 having a vanishing quadrupole frequency, as expected for 111Cd on substitutional sites in a cubic lattice, starts to develop around 300 K and reaches 100% at 700 K. Two well-defined EFG's having closely lying quadrupole frequencies and asymmetry parameters of ωQi = 49.1(3) Mrad/s, 77, η0= 0.10(2) and ωQ2 = 51.8(3) Mrad/s, η2 = 0.12(2), at room temperature, were identified in the temperature range from 250 to 530 K, and their (100) orientation in the lattice was determined. They are associated with electronic defects at the probe atoms.

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