On the Origin of the Contrast Inhomogeneities Found on In0.52Al0.48As Layers Grown on InP Substrates At High Temperatures

1992 ◽  
Vol 281 ◽  
Author(s):  
F. Peiro ◽  
A. Cornet ◽  
J. R. Morante ◽  
A. Georgakilas
Keyword(s):  
Activation Energy ◽  
High Temperatures ◽  
Substrate Interface ◽  
Present Work Deal ◽  
Inp Substrates

ABSTRACTThe present work deal with the coarse contrast modulation along the <010> directions observed in (100) planar view TEM observations of In0.52Al0.48As layers grown on InP substrates at temperatures higher than 550°C. The most important features of these contrast inhomogeneites are briefly reviewed. Besides, the appearance of the contrast in [011] cross-sectioned specimens is presented and its origin related to precipitates at the layer-substrate interface. The density of precipitates (ρp) has been found to increase as Tg rises, and an approximate value of the activation energy needed to induce the precipitation has been derived from the correlation of ρp and Tg.

High Temperature n- and p-type Doped Microcrystalline Silicon Layers Grown by VHF PECVD Layer-by-Layer Deposition

2003 ◽  
Vol 762 ◽  
Author(s):  
A. Gordijn ◽  
J.K. Rath ◽  
R.E.I. Schropp
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
High Temperatures ◽  
Continuous Wave ◽  
Hydrogen Plasma ◽  
Silicon Layer ◽  
Dark Conductivity ◽  
High Deposition Rate ◽  
Layer By Layer ◽  
Microcrystalline Silicon

AbstractDue to the high temperatures used for high deposition rate microcrystalline (μc-Si:H) and polycrystalline silicon, there is a need for compact and temperature-stable doped layers. In this study we report on films grown by the layer-by-layer method (LbL) using VHF PECVD. Growth of an amorphous silicon layer is alternated by a hydrogen plasma treatment. In LbL, the surface reactions are separated time-wise from the nucleation in the bulk. We observed that it is possible to incorporate dopant atoms in the layer, without disturbing the nucleation. Even at high substrate temperatures (up to 400°C) doped layers can be made microcrystalline. At these temperatures, in the continuous wave case, crystallinity is hindered, which is generally attributed to the out-diffusion of hydrogen from the surface and the presence of impurities (dopants).We observe that the parameter window for the treatment time for p-layers is smaller compared to n-layers. Moreover we observe that for high temperatures, the nucleation of p-layers is more adversely affected than for n-layers. Thin, doped layers have been structurally, optically and electrically characterized. The best n-layer made at 400°C, with a thickness of only 31 nm, had an activation energy of 0.056 eV and a dark conductivity of 2.7 S/cm, while the best p-layer made at 350°C, with a thickness of 29 nm, had an activation energy of 0.11 V and a dark conductivity of 0.1 S/cm. The suitability of these high temperature n-layers has been demonstrated in an n-i-p microcrystalline silicon solar cell with an unoptimized μc-Si:H i-layer deposited at 250°C and without buffer. The Voc of the cell is 0.48 V and the fill factor is 70 %.

Doping Effect in Nickel Oxide

2009 ◽  
Vol 289-292 ◽  
pp. 775-782 ◽  
Author(s):  
Zbigniew Jurasz ◽  
Krzysztof Adamaszek ◽  
Romuald Janik ◽  
Zbigniew Grzesik ◽  
Stanisław Mrowec
Keyword(s):  
Activation Energy ◽  
Nickel Oxide ◽  
High Temperatures ◽  
Oxygen Pressure ◽  
Pressure Dependence ◽  
Oxidation Rate ◽  
Doping Effect ◽  
Self Diffusion ◽  
Electron Holes ◽  
Influence Of Impurities

Detailed investigations of nonstoichiometry as well as chemical and self-diffusion in nickel oxide have shown that doubly ionised cation vacancies and electron holes are the predominant defects in this material. The present work is an attempt to demonstrate that aliovalent impurities (Cr, Al, Na and Li) may considerably influence the concentration of these defects and, consequently, the oxidation rate of nickel at high temperatures. It has been shown that small amounts of tri-valent impurities (Cr, Al) bring about an increase of the oxidation rate, while mono-valent ones (Li, Na) decrease the rate of oxidation. These phenomena may satisfactorily be explained in terms of a doping effect. All experiments have been carried out as a function of temperature (1373-1673 K) and oxygen pressure (1-105 Pa) and consequently, it was possible to determine the influence of impurities not only on the oxidation rate but also on the activation energy of reaction and its pressure dependence. The results of these investigations could again be elucidated in terms of doping effect.

Nucleation and Heterointerface Structure of InAs Epilayers Grown on InP Substrates

1992 ◽  
Vol 280 ◽  
Author(s):  
K. S. Chandra Sekhar ◽  
A. K. Ballal ◽  
L. Salamanca-Riba ◽  
D. L. Partin
Keyword(s):  
Surface Morphology ◽  
Electronic Properties ◽  
Growth Temperature ◽  
High Speed ◽  
Interface Roughness ◽  
Structural Defects ◽  
Lower Growth ◽  
Substrate Interface ◽  
Film Substrate ◽  
Inp Substrates

ABSTRACTHeteroepitaxial growth of indium arsenide films on indium phosphide substrates is being actively pursued since the electronic properties of these films make them promising materials for optoelectronic and other high speed devices. The various structural aspects of the film that affect their electronic properties are structural defects like dislocations, film-substrate interface roughness and chemical inhomogeneities. In InAs films, electrons accumulate at the film-air interface, making surface morphology an important factor that decides the electronic properties. The InAs films used in this study were grown on InP substrates by metal organic vapor deposition, at different temperatures. A higher growth temperature not only resulted in poor surface morphology of the film, but also created a rough film-substrate interface. However, at all deposition temperatures, the film-substrate interfaces are sharp. At lower growth temperature, the interfaces were flat. Films grown at lower temperatures had good surface morphology and a flat and shaip heterointerface.

Photoreflectance Characterization of the Semi-Insulating InP Substrate Interface with InGaAs and InAlAs Epilayers

1992 ◽  
Vol 281 ◽  
Author(s):  
Weimin Zhou ◽  
H. Shen ◽  
J. Pamulapati ◽  
M. Dutta ◽  
B. R. Bennett ◽  
...  
Keyword(s):  
Electron Transition ◽  
In Situ Monitoring ◽  
Signal Phase ◽  
Mbe Growth ◽  
Substrate Interface ◽  
Inp Substrate ◽  
Excitonic Transition ◽  
Inp Substrates

ABSTRACTPhotoreflectance (PR) has been performed on a series of undoped and n-type, InGaAs and InAlAs molecular beam epitaxy (MBE) grown layers with different In mole fractions, and epilayer thicknesses on Fe-doped semi-insulating (SI)-InP substrates. From investigations of the temperature dependence, time constant dependence and an additional cw light beam intensity dependence, three substrate peaks are identified as an excitonic transition from the substrate, a free electron transition near the interface which gives a Franz-Keldysh oscillation (KFO), and a transition from the spin-orbit split-off valence band. The results are indicative of a redistribution of charge near the substrate interface in the process of MBE growth; the associated PR signal (phase) could be used for in-situ monitoring of epilayer growth on SI-InP wafers.

THE REACTION OF HYDROGEN AND DEUTERIUM ATOMS WITH PROPANE

1939 ◽  
Vol 17b (12) ◽  
pp. 371-384 ◽  
Author(s):  
E. W. R. Steacie ◽  
N. A. D. Parlee
Keyword(s):  
Activation Energy ◽  
High Temperatures ◽  
Low Temperatures ◽  
Hydrogen Atoms ◽  
Temperature Range ◽  
Secondary Reactions

The reaction of hydrogen atoms with propane has been investigated over the temperature range 30° to 250 °C. by the Wood-Bonhoeffer method. The products are solely methane at low temperatures, and methane, ethane, and ethylene at higher temperatures.It is concluded that the results can be explained only by the assumption that the reaction[Formula: see text]is of importance. The bearing of this on the Rice-Herzfeld mechanisms is discussed. The activation energy of the reaction is 10 ± 2 Kcal.The main steps in the postulated mechanism are:Primary Reaction[Formula: see text]Secondary Reactions at Low Temperatures[Formula: see text]Additional Secondary Reactions at High Temperatures[Formula: see text]The reaction of deuterium atoms with propane was also investigated. It was found that the methane and ethane produced were highly deuterized, while the propane was not appreciably exchanged.

scholarly journals Estimation of Pore Size Distribution of Amorphous Silica-Based Membrane by the Activation Energies of Gas Permeation

Processes ◽  
2018 ◽  
Vol 6 (12) ◽  
pp. 239 ◽  
Author(s):  
Guozhao Ji ◽  
Xuechao Gao ◽  
Simon Smart ◽  
Suresh K. Bhatia ◽  
Geoff Wang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Pore Size Distribution ◽  
Apparent Activation Energy ◽  
Pore Size ◽  
Size Distribution ◽  
Cobalt Oxide ◽  
High Temperatures ◽  
Gas Permeation ◽  
Oscillator Model ◽  
Silica Membranes

Cobalt oxide silica membranes were prepared and tested to separate small molecular gases, such as He (dk = 2.6 Å) and H2 (dk = 2.89 Å), from other gases with larger kinetic diameters, such as CO2 (dk = 3.47 Å) and Ar (dk = 3.41 Å). In view of the amorphous nature of silica membranes, pore sizes are generally distributed in the ultra-microporous range. However, it is difficult to determine the pore size of silica derived membranes by conventional characterization methods, such as N2 physisorption-desorption or high-resolution electron microscopy. Therefore, this work endeavors to determine the pore size of the membranes based on transport phenomena and computer modelling. This was carried out by using the oscillator model and correlating with experimental results, such as gas permeance (i.e., normalized pressure flux), apparent activation energy for gas permeation. Based on the oscillator model, He and H2 can diffuse through constrictions narrower than their gas kinetic diameters at high temperatures, and this was possibly due to the high kinetic energy promoted by the increase in external temperature. It was interesting to observe changes in transport phenomena for the cobalt oxide doped membranes exposed to H2 at high temperatures up to 500 °C. This was attributed to the reduction of cobalt oxide, and this redox effect gave different apparent activation energy. The reduced membrane showed lower apparent activation energy and higher gas permeance than the oxidized membrane, due to the enlargement of pores. These results together with effective medium theory (EMT) suggest that the pore size distribution is changed and the peak of the distribution is slightly shifted to a larger value. Hence, this work showed for the first time that the oscillator model with EMT is a potential tool to determine the pore size of silica derived membranes from experimental gas permeation data.

Photoluminescence of Erbium Implanted in SiGe

1996 ◽  
Vol 422 ◽  
Author(s):  
S. J. Chang ◽  
D. K. Nayak ◽  
Y Shiraki
Keyword(s):  
Activation Energy ◽  
Optical Properties ◽  
High Temperatures ◽  
Room Temperature ◽  
Luminescence Centers ◽  
Pl Intensity ◽  
Er Doped

The optical properties of an Er-implanted SiGe sample have been studied Sharp and temperature-stable Er-related PL peaks were observed at around 1.5pm, which correspond to the Er 4I13/2 to 4I15/2 transition. It was found that the Er ions form more than three noncubic luminescence centers in the SiGe host. Although the PL intensity quenches at high temperatures, the Errelated PL signal can still be observed at room temperature. For a Si0.87Ge0.13:Er sample annealed at 850°C for 20 min, the activation energy is 130 meVwhich is slightly smaller than that of the Er-doped Si.

Characteristics of scale/substrate interface area of Si-containing low-carbon steels at high temperatures

2001 ◽  
Vol 308 (1-2) ◽  
pp. 250-257 ◽  
Author(s):  
Shigeji Taniguchi ◽  
Kozou Yamamoto ◽  
Daisuke Megumi ◽  
Toshio Shibata
Keyword(s):  
High Temperatures ◽  
Carbon Steels ◽  
Low Carbon ◽  
Interface Area ◽  
Low Carbon Steels ◽  
Substrate Interface

Comparison of Isothermal Anneal Techniques for be or Si Implanted S.I. InP

1985 ◽  
Vol 52 ◽  
Author(s):  
B. Molnar ◽  
H. B. Dietrich
Keyword(s):  
Activation Energy ◽  
Maximum Temperature ◽  
Rapid Thermal Anneal ◽  
Temperature Range ◽  
Isothermal Anneal ◽  
Additional Processing ◽  
Activation Data ◽  
Inp Substrates ◽  
Processing Steps

ABSTRACTThis paper presents a study of the annealing of Be and Si implants into InP. It compares rapid thermal anneal (RTA) and furnace anneal (FA) techniques over a temperature range of 600-;900° C. The results demonstrate that RTA results in activation and mobilities as good as those obtained by FA for both Si and Be implant. The background Fe concentration of S.I. InP substrates lead to substantial differences in activation. Arrhenius fit of optimal activation data of Si indicates an activation energy of 1.8 eV. The Si implants display no redistribution during either type of annealing, while the Be implants display more than one type of redistribution. Moreover, the complete description of the Be redistribution requires the knowledge of both the atomic and the electronic profiles. Capless annealing eliminates the additional processing steps of capping but it also sets a limit on the maximum temperature and time of the annealing.

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