Behavior of Deep Defects After Hydrogen Passivation in Znte Studied by Photoluminescence and Photoconductivity

1998 ◽  
Vol 510 ◽  
Author(s):  
S. Bhunia ◽  
D.N. Bose
Keyword(s):  
Thermal Activation ◽  
Hydrogen Plasma ◽  
Minority Carrier Lifetime ◽  
Activation Energies ◽  
Band Edge ◽  
Band Edge Emission ◽  
Hydrogen Passivation ◽  
Deep Acceptor ◽  
Strong Band ◽  
Deep Acceptor Level

AbstractThe effects of hydrogen passivation in undoped p-ZnTe single crystals were studied by photoluminescence (PL) and photoconductivity (PC) measurements. Samples were exposed to r.f hydrogen plasma at 250 °C for different durations. Before passivation PL peaks were observed at 2.06 eV, 1.47 eV, 1.33 eV and 1.06 eV. After 60 minutes exposure, samples showed strong band edge green luminescence at 2.37 eV due to an exciton bound to a Cu acceptor. Further exposure to plasma resulted in disappearance of 2.37eV and 2.34 eV peaks due to damage. In PC studies the dark current was found to decrease by a factor of 70 on 60 minutes passivation. From the temperature dependence of PC gain, the minority carrier lifetime τn, was found to go through a maximum of 4.5 × 10−7 sec at 220 K before passivation. After 60 minutes exposure, τn, remained constant at 4.5 × 10−7 sec for T > 220 K and decreased for T < 220 K. The activation energies of τn, were determined and show marked changes on passivation for T > 220 K. Comparison between PL and PC studies showed that the deep acceptor level OTe responsible for emission at 2.06 eV is passivated giving rise to strong band edge emission at 2.37 eV while emission due to the midgap impurity levels at 1.47, 1.33 and 1.05 eV remained unaffected. The thermal activation energies of the PL peaks have also been determined and allow the construction of a defect energy level diagram for ZnTe.

Synthesis and optical characterization of a high-quality ZnS substrate for optoelectronics and UV solar-energy conversion

RSC Advances ◽  
2016 ◽  
Vol 6 (84) ◽  
pp. 81053-81059 ◽  
Author(s):  
Ching-Hwa Ho ◽  
Min-Han Lin
Keyword(s):  
Solar Energy ◽  
Energy Conversion ◽  
Optical Characterization ◽  
Band Edge ◽  
Band Edge Emission ◽  
High Grade ◽  
Edge Emission ◽  
High Quality ◽  
Strong Band

A high-grade cubic ZnS substrate crystal with longer range order and a strong band-edge emission was clearly demonstrated.

Hydrogen Passivation of Interfacial Defects in MOCVD grown GaAs/InP

1989 ◽  
Vol 163 ◽  
Author(s):  
V. Swaminatan ◽  
U. K. Chakrabarthi ◽  
W. S. Hobson ◽  
R. Caruso ◽  
J. Lopata ◽  
...  
Keyword(s):  
Lattice Mismatch ◽  
Hydrogen Plasma ◽  
Chemical Vapor ◽  
Fold Increase ◽  
Peak Shift ◽  
Organic Chemical ◽  
Interfacial Region ◽  
Band Edge Emission ◽  
Hydrogen Passivation ◽  
Untreated Sample

AbstractThe results of a low temperature (5K) photoluminescence study of hydrogenation of GaAs on InP grown by metal organic chemical vapor deposition are presented. An emission band at ~ 1.4 eV originating from the GaAs/InP interracial region shows a 30 fold increase in intensity relative to the GaAs band edge emission after exposure to hydrogen plasma for 30 min at 250°C. This improvement in intensity is attributed to hydrogen passivation of defects at the heterointerface caused by the large (≈4%) lattice mismatch between GaAs and InP. The passivation effect recovers on annealing the hydrogenated sample at 350°C. Excitation dependence of the ~1.4 eV band suggests that the interfacial region consists of a compositionally graded layer. Further, this band shifts to higher energy on annealing the sample in the temperature range 150-450°C with the hydrogenated sample exhibiting a larger shift than the untreated sample. It is suggested that the annealing induced peak shift arises due to intermixing of the compositionally graded interface and that the degree of intermixing is greater in the hydrogenated sample compared to the untreated sample.

Effects of Hydrogen on the Deep Levels in Si, ZnO and Diamond Studied by Cathodoluminescence

2002 ◽  
Vol 719 ◽  
Author(s):  
Takashi Sekiguchi
Keyword(s):  
Point Defects ◽  
Deep Level ◽  
Hydrogen Plasma ◽  
Green Emission ◽  
Deep Levels ◽  
Band Edge Emission ◽  
Hydrogen Passivation ◽  
Edge Emission ◽  
Characteristic Emission ◽  
Zno Crystal

AbstractThe effects of hydrogen on the deep level luminescence in Si, ZnO and diamond were studied by means of cathodoluminescence. It is well known that most of the deep levels in Si are passivated by hydrogen. Scratch lines on Si surface, which do not show any characteristic luminescence, obtain so-called D-line luminescence by hydrogen plasma treatment. It indicates that only nonradiative defects are passivated but D-line luminescence is not passivated by hydrogenation. Contrarily, typical ZnO crystal shows the green emission, which is attributed to the point defects or impurities. Hydrogen completely passivates this green emission, and in turn, enhances the band edge emission. The effect of hydrogen passivation disappeared by the annealing at temperatures higher than 600 °C. Hydrogen behaves more peculiarly in diamond. The hydrogenated diamond film shows the characteristic emission around 2.3 eV in photon energy. Since it disappears by oxidization treatment, this emission is attributed to hydrogen at the subsurface region. The detailed study indicated that hydrogen in diamond has bistable states.

The enhancement of near-band-edge emission by hydrogen plasma treatment for Ga-doped ZnO, ZnO and ZnMgO films

2019 ◽  
Vol 92 ◽  
pp. 11-15 ◽  
Author(s):  
Xinhua Pan ◽  
Xiangyang Chen ◽  
Chenxiao Xu ◽  
Shanshan Chen ◽  
Yujia Zeng ◽  
...  
Keyword(s):  
Plasma Treatment ◽  
Hydrogen Plasma ◽  
Band Edge ◽  
Near Band Edge Emission ◽  
Near Band Edge ◽  
Band Edge Emission ◽  
Edge Emission ◽  
Doped Zno

Micro-Photoluminescence Mapping of Defect Structures in SiC Wafers

2007 ◽  
Vol 556-557 ◽  
pp. 383-386 ◽  
Author(s):  
John Hennessy ◽  
Tom Ryan
Keyword(s):  
Carrier Lifetime ◽  
Deep Level ◽  
Complex Function ◽  
Band Edge ◽  
Structural Defects ◽  
Band Edge Emission ◽  
Interfacial Defects ◽  
Pl Mapping ◽  
Boron Acceptor ◽  
Excitation Conditions

Micro-photoluminescence can be used to image electrically active structural defects in SiC. Under suitable excitation conditions it is possible to observe both band-edge PL and near bandedge PL from recombination via a shallow boron acceptor. The intensity of the band-edge emission is related to the carrier lifetime – and is reduced by the presence of structural or interfacial defects. The intensity of the deep level PL is a complex function of the number of radiative centers and the number of centers limiting carrier lifetime. Micro-PL mapping can provide information on the spatial distribution of electrically active defects in SiC.

Ultrafast Carrier Dynamics, Optical Amplification, and Lasing in Nanocrystal Quantum Dots

MRS Bulletin ◽  
2001 ◽  
Vol 26 (12) ◽  
pp. 998-1004 ◽  
Author(s):  
Victor I. Klimov ◽  
Moungi G. Bawendi
Keyword(s):  
Quantum Dots ◽  
Quantum Wells ◽  
Quantum Wires ◽  
Electronic States ◽  
Three Dimensions ◽  
Band Edge ◽  
Lasing Threshold ◽  
Wide Energy Range ◽  
Band Edge Emission ◽  
Edge States

Semiconductor materials are widely used in both optically and electrically pumped lasers. The use of semiconductor quantum wells (QWs) as optical-gain media has resulted in important advances in laser technology. QWs have a two-dimensional, step-like density of electronic states that is nonzero at the band edge, enabling a higher concentration of carriers to contribute to the band-edge emission and leading to a reduced lasing threshold, improved temperature stability, and a narrower emission line. A further enhancement in the density of the band-edge states and an associated reduction in the lasing threshold are in principle possible using quantum wires and quantum dots (QDs), in which the confinement is in two and three dimensions, respectively. In very small dots, the spacing of the electronic states is much greater than the available thermal energy (strong confinement), inhibiting thermal depopulation of the lowest electronic states. This effect should result in a lasing threshold that is temperatureinsensitive at an excitation level of only 1 electron-hole (e-h) pair per dot on average. Additionally, QDs in the strongconfinement regime have an emission wavelength that is a pronounced function of size, adding the advantage of continuous spectral tunability over a wide energy range simply by changing the size of the dots.

Thermal activation energies of Mg in GaN:Mg measured by the Hall effect and admittance spectroscopy

2000 ◽  
Vol 88 (5) ◽  
pp. 2564-2569 ◽  
Author(s):  
D. J. Kim ◽  
D. Y. Ryu ◽  
N. A. Bojarczuk ◽  
J. Karasinski ◽  
S. Guha ◽  
...  
Keyword(s):  
Hall Effect ◽  
Thermal Activation ◽  
Activation Energies ◽  
Admittance Spectroscopy
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