scholarly journals A Photocapture Test of DX-Center Models

1989 ◽  
Vol 163 ◽  
Author(s):  
Harold P. Hjalmarson ◽  
S. R. Kurtz ◽  
T. M. Brennan
Keyword(s):  
Conduction Band ◽  
Cross Section ◽  
Threshold Energy ◽  
Photoionization Cross Section ◽  
Persistent Photoconductivity ◽  
Dx Centers ◽  
Null Result ◽  
Dx Center

AbstractThe DX-center model is widely used to explain data for the persistent photoconductivity (PPC) effect. An analysis of the DX-center model suggests a new experiment to test its correctness. In this experiment, photons near the threshold energy of the photoionization cross-section for the DX-center induce transitions from the partially occupied conduction band to empty DX-centers. This mechanism, which we call photocapture, competes with the usual photoionization which empties the DX-centers. The photocapture cross-section is estimated and an experimental attempt is made to detect photocapture. The significance of the null result is discussed.

DX Center Energy Level in InxAl1−xAs Compounds

1999 ◽  
Vol 573 ◽  
Author(s):  
Hüseyin Sari ◽  
Harry H. wieder
Keyword(s):  
Energy Level ◽  
Conduction Band ◽  
Canonical Ensemble ◽  
Grand Canonical Ensemble ◽  
Persistent Photoconductivity ◽  
Dx Centers ◽  
Indium Concentration ◽  
Self Consistent ◽  
Dx Center ◽  
Grand Canonical

ABSTRACTThe presence of DX centers in InxAl1−xAs, primarily in the indirect portion of the InxAl1−xAs bandgap, has been determined using modulation doped InxAl1−xAs/InyGa1−yAs heterostructures by means of persistent photoconductivity (PPC) and galvanomagnetic measurements. From the cooling bias experiment, the PPC, and self consistent Poisson and Schrddinger simulations the ratio of the ionized shallow donors to the DX centers is obtained. Using this ratio in the grand canonical ensemble (GCE) the energy level of DX centers is determined. It is found that the DX energy level merges with the conduction band at x ≅ 0.42 and is resonant with the conduction band in higher indium concentration.

DX Centers in GaAs and AlxGal-x.As: Properties and Influence on Material and Device Characteristics

1987 ◽  
Vol 104 ◽  
Author(s):  
P. M. Mooney
Keyword(s):  
Low Temperature ◽  
Carrier Concentration ◽  
Conduction Band ◽  
Energy State ◽  
Free Carrier ◽  
Free Carrier Concentration ◽  
Persistent Photoconductivity ◽  
Dx Centers ◽  
Compensation Mechanisms ◽  
Dx Center

ABSTRACTThe DX center, the lowest energy state of the donor in AlGaAs with x > 0.22, is responsible for the reduced conductivity as well as the persistent photoconductivity observed in this material at low temperature. Extensive studies of the properties of this level and of its effects on the characteristics of some heterojunction devices are reviewed here. Recent measurements are presented showing that the characteristics of the DX center remain essentially unchanged when it is resonant with the conduction band (x < 0.22) and that, independent of other compensation mechanisms, the DX center therefore limits the free carrier concentration in GaAs to a maximum of about 2×1019 cm− 3.

scholarly journals Large Persistent Photochromic Effect Due to DX Centers in AlSb Doped with Selenium

1995 ◽  
Vol 378 ◽  
Author(s):  
P. Becla ◽  
A. G. Witt ◽  
J. Lagowski ◽  
W. Walukiewicz
Keyword(s):  
Absorption Coefficient ◽  
Conduction Band ◽  
Spectral Range ◽  
Donor Level ◽  
Dx Centers ◽  
Enhanced Absorption ◽  
Photochromic Effect ◽  
Dx Center

AbstractA large photochromic effect has been observed in bulk AlSb crystals doped with Se. Illumination with the light of energy higher than 1 eV leads to an increase of the absorption coefficient in the spectral range 0.1 eV to 1.6 eV. The enhanced absorption is persistent at the temperatures below about 100 K. The effect is a manifestation of a DX-like bistability of Se donors. The illumination transfers the electrons from the DX center to a metastable hydrogenic level. The increased absorption with peaks around 0.2 eV and 0.5 eV is due to photoionization from the donor level to X1 and X3 minima of the conduction band

Pressure-dependent DLTS Experiments on Si-DOPED AlGaAs

1987 ◽  
Vol 104 ◽  
Author(s):  
John W. Farmer ◽  
Harold P. Hjalmarson ◽  
G. A. Samara
Keyword(s):  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Defect Complex ◽  
Persistent Photoconductivity ◽  
Dx Centers ◽  
Si Doped ◽  
Dx Center ◽  
Transient Spectroscopy ◽  
Dlts Spectra

ABSTRACTPressure dependent Deep Level Transient Spectroscopy (DLTS) experiments are used to measure the properties of the deep donors (DX-centers) responsible for the persistent photoconductivity effect in Si-doped AlGaAs. The sample dependence of the DLTS spectra shows evidence for a defect complex involved in the DX-center.

Impact of conduction band non-parabolicity and dielectric mismatch on photoionization cross section of donor bound polaron in spherical GaN/InN core-shell nanoparticle

2021 ◽  
Vol 93 (1) ◽  
pp. 10401
Author(s):  
Abdelali Talbi ◽  
Mohamed El Haouari ◽  
Khalid Nouneh ◽  
El Mustapha Feddi ◽  
Mohammed Addou
Keyword(s):  
Conduction Band ◽  
Cross Section ◽  
Optical Transition ◽  
Photoionization Cross Section ◽  
Blue Shift ◽  
Core Shell ◽  
Mass Approximation ◽  
High Control ◽  
Dielectric Mismatch ◽  
Dielectric Environment

Understanding the behavior of single dopant in semiconductors is a challenge to attain a high control on optoelectronic devices. Based on the fact that the external perturbations have an important impact on properties of doped nanocrystals, we have studied the simultaneous effects of phonons and conduction band non-parabolicity combined to dielectric mismatch and donor position on the photoionization cross section of an off-center donor in spherical GaN/InN core-shell quantum dots. The calculations were carried out within the framework of the effective-mass approximation and the eigenvalues equation has been solved using the Ritz variational method. The examination of the photoionization cross section, corresponding to the first donor energy level and the non-parabolic conduction band optical transition, shows clearly that the existence of non-parabolicity band or dielectric environment causes a blue shift of resonance peaks while the existence of phonon red shift them with a non-neglected variations in their intensity. The donor position has also an important effect on peaks position and amplitude.

Absolute photoionization cross section measurements of Xe+ions in the 4d threshold energy region

2001 ◽  
Vol 34 (17) ◽  
pp. 3493-3499 ◽  
Author(s):  
Yoh Itoh ◽  
Akira Ito ◽  
Masashi Kitajima ◽  
Tetsuo Koizumi ◽  
Takao M Kojima ◽  
...  
Keyword(s):  
Cross Section ◽  
Energy Region ◽  
Threshold Energy ◽  
Photoionization Cross Section

Photoionization cross-section of the DX center in Te-doped AlxGa1−xSb

1998 ◽  
Vol 83 (1) ◽  
pp. 491-496 ◽  
Author(s):  
A. Baraldi ◽  
C. Ghezzi ◽  
R. Magnanini ◽  
A. Parisini ◽  
L. Tarricone ◽  
...  
Keyword(s):  
Cross Section ◽  
Photoionization Cross Section ◽  
Dx Center

XUV Absorption Spectra of Carbon Ions

1988 ◽  
Vol 102 ◽  
pp. 71-73
Author(s):  
E. Jannitti ◽  
P. Nicolosi ◽  
G. Tondello
Keyword(s):  
Absorption Spectra ◽  
Cross Section ◽  
Theoretical Calculations ◽  
Photoionization Cross Section ◽  
Carbon Ions

AbstractThe photoabsorption spectra of the carbon ions have been obtained by using two laser-produced plasmas. The photoionization cross-section of the CV has been absolutely measured and the value at threshold, σ=(4.7±0.5) × 10−19cm2, as well as its behaviour at higher energies agrees quite well with the theoretical calculations.

scholarly journals Photoionization Cross-Sections of Carbon-Like N+ Near the K-Edge (390–440 eV)

Atoms ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 27
Author(s):  
Jean-Paul Mosnier ◽  
Eugene T. Kennedy ◽  
Jean-Marc Bizau ◽  
Denis Cubaynes ◽  
Ségolène Guilbaud ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Section ◽  
Cross Sections ◽  
Experimental Studies ◽  
Photoionization Cross Section ◽  
Theoretical Work ◽  
Rydberg Series ◽  
R Matrix ◽  
Resonance Strengths ◽  
Nitrogen Ion

High-resolution K-shell photoionization cross-sections for the C-like atomic nitrogen ion (N+) are reported in the 398 eV (31.15 Å) to 450 eV (27.55 Å) energy (wavelength) range. The results were obtained from absolute ion-yield measurements using the SOLEIL synchrotron radiation facility for spectral bandpasses of 65 meV or 250 meV. In the photon energy region 398–403 eV, 1s⟶2p autoionizing resonance states dominated the cross section spectrum. Analyses of the experimental profiles yielded resonance strengths and Auger widths. In the 415–440 eV photon region 1s⟶(1s2s22p2 4P)np and 1s⟶(1s2s22p2 2P)np resonances forming well-developed Rydberg series up n=7 and n=8 , respectively, were identified in both the single and double ionization spectra. Theoretical photoionization cross-section calculations, performed using the R-matrix plus pseudo-states (RMPS) method and the multiconfiguration Dirac-Fock (MCDF) approach were bench marked against these high-resolution experimental results. Comparison of the state-of-the-art theoretical work with the experimental studies allowed the identification of new resonance features. Resonance strengths, energies and Auger widths (where available) are compared quantitatively with the theoretical values. Contributions from excited metastable states of the N+ ions were carefully considered throughout.

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