Complex Defects in GaAs and GaP

1982 ◽  
Vol 14 ◽  
Author(s):  
P. J. Lin-Chung
Keyword(s):  
Electronic States ◽  
Group Iv ◽  
Experimental Results ◽  
Large Cluster ◽  
Defect Level ◽  
Defect Complexes ◽  
Densities Of States ◽  
Local Densities ◽  
Defect Levels ◽  
Gap States

ABSTRACTA study of the electronic states associated with divacancy defects and with the defect complexes involving an anion antisite with a group IV atom (Ac-IV) in GaAs and GaP is reported. The local densities of states have been determined using the large cluster recursion approach. The properties as well as the position of the gap states of the divacancy defect in GaAs are found to be consistent with the experimental results for the EL2 level. The change of the position of the defect levels of (Ac-IV) as a result of the change of bonding is analyzed. The effect of GaAs-A&As interface on the (Ac-IV) defect level is also examined.

Electronic Structure of Epitaxial SiO2/Si(100) Interfaces

1989 ◽  
Vol 159 ◽  
Author(s):  
T. Motooka
Keyword(s):  
Tight Binding ◽  
Interface States ◽  
Photoelectron Spectra ◽  
Band Spectrum ◽  
Binding Model ◽  
Initial Oxidation ◽  
Recursion Method ◽  
Densities Of States ◽  
Local Densities ◽  
Gap States

ABSTRACTThe local densities of states (LDOS) of epitaxial SiO, layers on Si(100) surfaces have been calculated using the recursion method combined with the Harrison's universal tight-binding model. The interface states associated with strained epitaxial layers of β-cristobalite (√2×√2)R45° and tridymite (1010)<0001> || Si(100)<011> were examined. In the β-cristobalite layer, gap states due to the surface Si dangling bonds appeared while they were eliminated by H termination. In the tridymite layer, the interface states primarily composed of the surface Si back bonds appeared near the Si conduction band minimum. Comparing the calculated DOS with photoelectron spectra for initial oxidation processes of clean Si(100), it was found that the valence band spectrum from the initial oxide formed at ∼300°C resembled that of the β-cristobalite layer.

The Optical Admittance Spectroscopy of the Vanadium Donor and Acceptor Levels in Semi-Insulating 4H-SiC and 6H-SiC

2006 ◽  
Vol 527-529 ◽  
pp. 647-650
Author(s):  
Won Woo Lee ◽  
Mary Ellen Zvanut
Keyword(s):  
Thermal Relaxation ◽  
Admittance Spectroscopy ◽  
Defect Level ◽  
Defect Complexes ◽  
Donor And Acceptor ◽  
Defect Levels

The purpose of this study is to determine the vanadium defect levels in semi-insulating 4H-SiC and 6H-SiC using optical admittance spectroscopy (OAS). OAS data show several distinct peaks for the vanadium-doped SI 4H-SiC and 6H-SiC. Comparison of the data for the two polytypes suggests that peaks at 0.67 ± 0.02 eV and 0.70 ± 0.02 eV in 6H substrates and 0.75 ± 0.02 eV in 4H substrates are related to V3+/4+ levels at the cubic sites. A peak at 0.87 ± 0.02 eV in the 6H sample is assigned to the same defect level at the hexagonal site and the associated transition in 4H was observed at 0.94 ± 0.02 eV in our spectra. The donor levels are thought to be related to peaks at 1.94 ± 0.05 eV and 1.87 ± 0.05 eV in 4H and 6H samples, respectively. The differences between the values obtained from the optical admittance measurements and those reported in the literature are attributed to thermal relaxation and/or contributions from defect complexes.

Commentary on local densities of states, surface bonds and rate processes

1986 ◽  
Vol 318 (1541) ◽  
pp. 135-139 ◽  
Keyword(s):  
Electron Spectroscopy ◽  
Main Part ◽  
Catalytic Reactions ◽  
Solid Surfaces ◽  
Densities Of States ◽  
Rate Processes ◽  
Local Densities ◽  
Structure And Bonding ◽  
The Many

Although the main part of the title of this meeting is ‘ Studies of the surfaces of solids by electron spectroscopy’, the papers presented also cover some of the wider aspects of these studies, and I wish to pursue some of these here. I remark first that most of the systems studied by surface-sensitive spectroscopies are not technologically important, or even interesting in their own right. What makes them important and interesting is that the solids studied are, or are related to, catalysts, and the adsorbates studied are reactants, products or intermediates in important catalytic reactions. Consequently I ask the question: what is the relevance to catalysis of studies of structure, and bonding at solid surfaces? From among the many answers that might be given, I select two.

The influence of hydrogen saturation on the local densities of states in small Si, Ge and GaAs clusters

1981 ◽  
Vol 106 (1-3) ◽  
pp. A188
Author(s):  
G. de Meyer ◽  
R. Hoogewijs ◽  
W. Lambrecht ◽  
J. Vennik ◽  
G. Dalmai
Keyword(s):  
Hydrogen Saturation ◽  
Densities Of States ◽  
Local Densities

Electronic Properties and Defect Levels Induced by n/p-Type Defect-Complexes in Ge

2021 ◽  
Author(s):  
Emmanuel Igumbor ◽  
Okikiola Olaniyan ◽  
Guy Moise Dongho-Nguimdo ◽  
Edwin Mapasha ◽  
Sohail Ahmad ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Defect Complexes ◽  
Type Defect ◽  
Defect Levels

scholarly journals ESTUDO COMPARATIVO ENTRE O FIO DE NAILON E A LINHA DE PESCA (POLIAMIDA) E A SUA APLICABILIDADE COMO FIO CIRÚRGICO

1999 ◽  
Vol 4 (1) ◽  
Author(s):  
SHEILA CANEVESE RAHAL ◽  
MANOEL ÁLVARO GUIMARÃES ◽  
JOSÉ VICENTE FORTES ◽  
HÉLIO LANGONI ◽  
PEDRO HELIO LUCCHIARI
Keyword(s):  
Adverse Effect ◽  
Comparative Study ◽  
Physical Properties ◽  
Group Iv ◽  
Experimental Results ◽  
Control Group ◽  
Group Iii ◽  
Nylon Thread ◽  
Group I ◽  
Mucous Membranes

"Linhas de pesca"* em diâmetros de 0,15mm; 0,20mm; 0,25mm; 0,30mm foram divididas em quatro grupos, contendo dez amostras de cada diâmetro: grupo I - controle; grupo II - linhas colocadas em frasco com pastilhas de formalina; grupo III - um ciclo de autoclavagem (30 minutos à 121 C, seguido por 10 minutos de secagem à 37 C em estufa); grupo IV - dois ciclos de autoclavagens. Foram avaliadas quanto: comprimento, calibre, resistência no nó e alongamento. Comparativamente foram examinados fios de náilon cirúrgico nas numerações 0, 1-0, 2-0, 3-0, 4-0 e 5-0 (10 amostras de cada um). Pelos resultados da análise estastística, verificou-se que a esterilização pelo calor úmido exerceu um efeito adverso na resistência da "linha de pesca". Por outro lado não houve diferenças na resistência, calibre e alongamento da "linha de pesca" entre o primeiro e segundo ciclo de autoclavagem. As “linhas” mantidas em pastilhas de formalina mantiveram na sua maioria suas características originais de resistência, comprimento, diâmetro e alongamento quando comparada ao grupo controle, entretanto, cabe lembrar que o formaldeído é considerado irritante para pele e membrana mucosa. Foi possível concluir que a "linha de pesca" apresenta características semelhantes ao fio cirúrgico, podendo ser mantida em pastilhas de formalina ou esterilizada em autoclave, lembrando que a autoclavagem altera algumas de suas propriedades físicas. Abstract A comparative study has been carried out between fishing lines and nylon thread in regard to their applicability as surgical thread. Four groups of 10 fishing lines in each of the following diameters = 0.15, 0.20, 0.25 and 0.30 mm = were subjected to the following treatments: group I, control; group II sterilized with formalin tablets; group III, autoclaved 30 minutes at 121oC; group IV, autoclaved twice 30 minutes at 121oC. The following parameters were then considered: length, caliber, resistance at the knot, and elongation. Ten samples of each surgical 0, 1.0, 2.0, 3.0, 4.0 and 5.0 nylon threads were used in comparatively similar experiments as the ones carried out with the fishing lines. According to the statistical analyses of the experimental results, it has been found that the sterilization by means of the humid heat exerts an adverse effect on the resistance of the fishing line. However, no differences were found between the effect displayed by two cycles sterilization compared with the fishing lines subjected to only one cycle. The threads maintained in formalin kept the majority of their original properties of resistance, length, diameter and elongation when compared with the control group. It is known, however that formaldehyde is an irritant chemical towards the skin and the mucous membranes. It was possible to conclude: a. fishing lines display characteristics similar to that ones of the nylon surgical thread; b. they can be maintained in formalin solution; c. autoclave sterilization alters some of their physical properties.

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