Study of DX Centers in GaAs1−xPx :Te

1987 ◽  
Vol 104 ◽  
Author(s):  
J. Kaniewski ◽  
M. Kaniewska
Keyword(s):  
Transition Region ◽  
Vapor Phase ◽  
Thermal Activation ◽  
Phosphorus Content ◽  
Alloy Composition ◽  
Thermal Emission ◽  
Exponential Behavior ◽  
Dx Centers ◽  
Dx Center ◽  
Parameter Values

ABSTRACTA capacitance study of GaAs1−xPx : Te. x > 0.2, obtained by vapor phase epitaxy, has revealed two DX centers, characterized by thermal activation energies ΔEA = 0.18 eV and ΔEB = 0.39 eV. and photoionization energies 0.6 eV and 1.1 eV, respectively. Both traps show strong non-exponential behavior in thermal emission and capture processes. It is shown that correct parameter values for DX centers can be determined from measurements of the transition region width. This method, which allows us to circumvent alloy effects, has been used to study DX center parameters as a function of the phosphorus content. It is demonstrated that the level B is linked to the X minimum, and that the barrier height for electron capture at this trap, with respect to the indirect minimum, is independent of alloy composition.

Evidence for Metastabile State of DX Center in AxGa1-xAs

1992 ◽  
Vol 262 ◽  
Author(s):  
Subhasis Ghosh ◽  
Vikram Kumar
Keyword(s):  
Activation Energy ◽  
Deep Level Transient Spectroscopy ◽  
Thermal Activation ◽  
Deep Level ◽  
Thermal Activation Energy ◽  
Dx Centers ◽  
Dx Center ◽  
Transient Spectroscopy ◽  
Silicon Doped ◽  
First Time

ABSTRACTPhoto-Deep Level Transient Spectroscopy with 1.38 eV light reveals a new level with thermal activation energy 0.2 eV of DX centers in silicon doped Alx Ga1-xAs (x = 0.26) for the first time. The observation of this level directly proves the negative-U properties of DX centers and the existence of thermodynamically metastable state DX.

DX Centers in AlGaAs and Pressurised GaAs

1993 ◽  
Vol 300 ◽  
Author(s):  
S. Anand ◽  
S. Subramanian ◽  
B. M. Arora ◽  
Y. C. Lu ◽  
E. Bauser
Keyword(s):  
Low Temperature ◽  
Effective Mass ◽  
Charge State ◽  
Hall Mobility ◽  
Thermal Emission ◽  
Dx Centers ◽  
Emission Properties ◽  
Dx Center ◽  
Neutron Transmutation

ABSTRACTIn this paper, we present results of our investigations on some aspects of the DX centers. It is shown from the low temperature Hall mobility measurements that the charge state of the DX center is neutral supporting the positive U model for the DX center. Hall and DLTS measurements on Al-rich Al0.8Ga0.2As:Te sample show a reversal in the ordering of the energies of the hydrogenic and deep states of the Te donor, with the DX state lying higher than the X valley related effective mass state. Thermal emission properties of the pressure induced DX states of Ge and Se donors in neutron transmutation doped (NTD) GaAs are discussed.

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 Centers and III-V Device Performance

1990 ◽  
Vol 184 ◽  
Author(s):  
Elias Muñoz-Merino
Keyword(s):  
Optical Properties ◽  
Low Temperatures ◽  
Thermal Emission ◽  
Systematic Research ◽  
Device Performance ◽  
Dx Centers ◽  
Noise Characteristics ◽  
Deep Donor ◽  
Donor States ◽  
Bipolar Device

ABSTRACTThe properties of deep donor states (DX's centers) in III-V alloys are reviewed in relation to their influence on the device characteristics and limitations. Because of the systematic research being performed on AlGaAs, most of the information presented refers to such material. The electron thermal emission and capture properties of the DX's are then related to the DC and noise characteristics in heterojunction transistors. The optical properties of DX centers indicate a clear difference between unipolar and bipolar device performance at low temperatures. The technical efforts to avoid DX centers will also be described.

SIGNIFICANCE OF DX-CENTERS FOR ACOUSTIC INDUCED RECONSTRUCTION PROCESSES OF DEFECTS IN GaN/AlGaN

2021 ◽  
Vol 56 ◽  
pp. 61-70
Author(s):  
Ya. M. Olikh ◽  
Keyword(s):  
Electron Concentration ◽  
Lattice Parameter ◽  
Central Position ◽  
Loading Frequency ◽  
Acoustic Action ◽  
Effective Electron ◽  
Dx Centers ◽  
Centrally Symmetric ◽  
Dx Center ◽  
Action Process

The experimental results of amplitude effects are compared (from an ultrasonic wave deformation amplitude – a tension τUS) for electron concentration and changes of the lattice parameter on the same sample GaN/Al0.2Ga0.8N/GaN/AlN. It has been experimentally established that at ultrasonic loading (frequency 5–10 MHz, amplitude – towards 2·104 W/m2) there is a nonlinear increase in the effective electron concentration and an increase in the lattice parameter; at the same time, the mobility of electrons decreases and μН(τUS) ~ |τUS|. The energy parameters of the acoustic activation charge carriers process are calculated from the approximation of experimental amplitude changes – Еа ≈ 50 meV and γn(300 K) ≈ 2,5·10-27 m3. The amplitude dependences (increase) of the relative lattice parameter change (ΔС/С) from the tension τUS have been investigated experimentally at different frequencies. The energy of DX-center transition UDX ≈ 108 meV and the activation volume of this transition γDX ≈ 6,6·10-27 m3 are calculated from the approximation of the experimental amplitude changes. The revealed correlation of the magnitude of acoustic induced effects in different experiments allows to build a quantitative energy model of the acoustic action process based on the properties of metastable DX centers. It is shown that the acoustic induced process occurs due to the dimensional displacement of the DX-center atom (a background impurity of silicon atoms) from the non-central position to the centrally symmetric one; herewith DX-center is ionized, one goes into the d0-state. It is believed that the changes are most likely to occur near penetrating dislocations in the barrier layer Al0.2Ga0.8N – acoustic modulated oscillations of the distance between the possible positions of the donor atom lead to a decrease in the barrier to the displacement of the defect.

DX Center Analysis in Sn DOPED AlGaAs Layer of Double Heterostructures

1987 ◽  
Vol 104 ◽  
Author(s):  
M. Kaniewska ◽  
J. Kaniewski
Keyword(s):  
Thermal Activation ◽  
Lattice Relaxation ◽  
Electron Capture Cross Section ◽  
Final State ◽  
Al Content ◽  
Double Heterostructures ◽  
Algaas Layer ◽  
Large Lattice ◽  
Dx Center ◽  
Dlts Spectra

ABSTRACTCapacitance as well as photovoltage response methods have been used to analyse DX centers in the N–type AlGaAs:Sn layer of double heterostructures. DLTS spectra have revealed two deep traps. The first center (ΔE1 = 0.20eV) has been interpreted as the DX center related to Sn. In this paper, it is suggested that the second trap, with thermal activation energy equal to ΔE2 = 0.33eV, is also a DX center due to Sn, connected with another final state (the L minimum) of thermal processes. C-T characteristics and DLTS spectra have been compared with photovoltage spectra to find a correlation between the trap populations and Al content. The binding energy of the trap 2, as well as the temperature dependence of the electron capture cross-section, have been determined from measurements of the transition region width. Photoionization measurements confirm that there is large lattice relaxation when an electron is captured at the trap.

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

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.

Observation of Midgap States in GaN with Optical-Isothermal Capacitance Transient Spectroscopy

1996 ◽  
Vol 449 ◽  
Author(s):  
P. Hacke ◽  
H. Miyoshi ◽  
K. Hiramatsu ◽  
H. Okumura ◽  
S. Yoshida ◽  
...  
Keyword(s):  
Vapor Phase ◽  
Thermal Emission ◽  
Vapor Phase Epitaxy ◽  
Deep Levels ◽  
Hydride Vapor Phase Epitaxy ◽  
Measured Concentration ◽  
Transient Spectroscopy ◽  
Capacitance Transient ◽  
Sequential Appearance ◽  
Isothermal Capacitance Transient Spectroscopy

ABSTRACTOptical-isothermal capacitance transient spectroscopy (O-ICTS) was used to distinguish the deep levels which occur in unintentionally doped n-type GaN by means of their characteristic optical cross section. GaN grown by metalorganic vapor phase epitaxy (MOVPE) and hydride vapor phase epitaxy (HVPE) were compared. Correspondence between optical and thermal emission characteristics of previously discovered levels, E2 (∼Ec-0.55 eV) and E4 (∼EC-1.0 eV), were clearly determined by observing their sequential appearance in the ICTS spectra. Whether by thermal or optical stimulation, the emission from E4 was found to be broad in nature; it is consequently believed to involve a defect. The total measured concentration of deep levels, including a prominent level which photoionizes in the range 2.5 to 3.0 eV below the conduction band, is greater in the GaN grown by MOVPE than by HVPE that was tested.

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.

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