Selective Area Etching of GaN and AlGaN by Thermally Chemical Reaction in Hydrogen Ambient

1997 ◽  
Vol 482 ◽  
Author(s):  
K. Hiramatsu ◽  
H. Matsushima ◽  
H. Hanai ◽  
N. Sawaki
Keyword(s):  
Chemical Reaction ◽  
Annealing Temperature ◽  
Etching Rate ◽  
The Other ◽  
Surface Etching ◽  
Selective Area ◽  
Other Hand ◽  
Different Temperatures ◽  
Ambient Gases ◽  
Ambient Gas

AbstractThe selective area etching of wurtzite GaN (0001) and AlGaN (0001) with SiO2 masks is investigated for different temperatures of 800 to 1 100°C and different ambient gases of H2, N2 and Ar including NH3. The etching rate of GaN increases with increasing annealing temperature under H2 ambient. This etching is attributed to the chemical reaction between Ga-N and H2. On the other hand, the etching of GaN does not occur in the N2 or Ar ambient gas. The NH3 gas in H2 ambient suppresses the chemical reaction, while the NH3 gas in N2 enhances it. The surface etching of Al0.1Ga0.9N is not observed even in H2 ambient.

scholarly journals Studying and fabricating p - type transparent conducting antimony - doped SnO2 thin films by magnetron sputtering

2015 ◽  
Vol 18 (1) ◽  
pp. 23-33
Author(s):  
Phuc Huu Dang ◽  
Duan Van Nguyen ◽  
Vu Si Hoai Nguyen ◽  
Hieu Van Le ◽  
Tran Le
Keyword(s):  
Magnetron Sputtering ◽  
Hole Concentration ◽  
The Other ◽  
Working Pressure ◽  
Rutile Structure ◽  
Different Temperatures ◽  
Ambient Gas ◽  
Optimum Annealing Temperature ◽  
P Type ◽  
Deposited Films

Sb doped tin oxide films (ATO) were fabricated on Quart glasses from (SnO2 + Sb2O3) mixture ceramic target by direct current (DC) magnetron sputtering in Ar ambient gas at working pressure of 2.10-3 torr. X ray diffraction (XRD), Hall - effect measurements and UV-vis spectra were performed to characterize the deposited films. The substrate temperature of films was investigated for two ways. Films were annealed in Ar ambient gas after deposited at room temperature in one way. They were deposited directly with different temperatures in the other. It is found that the fabricated of ATO films in the first way was easier than the other. Deposited films showed p type electrical property, polycrystalline tetragonal rutile structure and their average transmittance was above 80 % in visible light range at the optimum annealing temperature of 500oC. The best electrical properties of film were obtained on 10 %wt Sb2O3 doped SnO2 target with its resistivity, hole concentration and Hall mobility are 0.55 Ω.cm, 1.2.1019 cm-3 and 0.54 cm2V-1s-1, respectively.

Effect of the Annealing Temperature on Dielectric Properties of Bi1.5Zn1.0Nb1.5O7 Films Prepared by MOCVD

2008 ◽  
Vol 388 ◽  
pp. 175-178
Author(s):  
Hiroshi Funakubo ◽  
Shingo Okaura ◽  
Muneyasu Suzuki ◽  
Hiroshi Uchida ◽  
Seiichiro Koda
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Temperature Coefficient ◽  
Annealing Temperature ◽  
Relative Dielectric Constant ◽  
Fused Silica ◽  
The Other ◽  
Other Hand ◽  
Silica Substrates

Effect of annealing temperature on the dielectric properties of Bi1.5Zn1.0Nb1.5O7 films prepared on (111)Pt//(001)Al2O3 and (111)Pt/fused silica substrates by MOCVD was investigated. The tunability and the inverse of the dielectric loss [1/ (tan )] increased with increasing annealing temperature. Relative dielectric constant and temperature coefficient of the capacitance (TCC) increased with the crystallinity of the films. On the other hand, (1/tan ) was independent of the crystallinity of the films, but was dramatically increased by the annealing.

Pb-free solders: Predicting of some physicochemical properties of Ag–Cu–Sn material at different temperatures

2016 ◽  
Vol 15 (07) ◽  
pp. 1650062 ◽  
Author(s):  
Rachida M’chaar ◽  
Mouloud El Moudane ◽  
Abdelaziz Sabbar ◽  
Ahmed Ghanimi
Keyword(s):  
Surface Tension ◽  
Physicochemical Properties ◽  
Molar Volume ◽  
The Other ◽  
Ternary Alloys ◽  
Other Hand ◽  
Different Temperatures ◽  
Experimental Values ◽  
Increasing Temperature ◽  
Good Agreement

In this paper, the surface tension, molar volume and density of liquid Ag–Cu–Sn alloys have been calculated using Kohler, Muggianu, Toop, and Hillert models. In addition, the surface tension and viscosity of the Ag–Cu–Sn ternary alloys at different temperatures have been predicted on the basis of Guggenheim and Seetharaman–Sichen equations, respectively. The results show that density and viscosity decrease with increasing tin and increasing temperature for the all studied models. While the surface tension shows a different tendency, especially for the Kohler and Muggianu symmetric models. On the other hand, the molar volume increases with increase of temperature and tin compositions. The calculated values of surface tension and density of Ag–Cu–Sn alloys are compared with the available experimental values and a good agreement was observed.

Effect of Surface Etching Conditions on Stacking Faults in 4H-SiC Epitaxy

2019 ◽  
Vol 963 ◽  
pp. 119-122
Author(s):  
Tawhid Rana ◽  
Gil Yong Chung ◽  
Steve Anderson ◽  
Ian Manning ◽  
Willie Bowen ◽  
...  
Keyword(s):  
Stacking Faults ◽  
Gas Mixtures ◽  
Stacking Fault ◽  
High Density ◽  
Experimental Results ◽  
The Other ◽  
Surface Etching ◽  
Other Hand ◽  
Effect Of Surface

Epilayers grown on substrates etched by various etching conditions were studied for stacking fault defects. Substrates were etched by H2, H2+ HCl and H2 + CxHy gases prior to epilayer growth for comparison. High density of SF was observed in the epilayers when H2+HCl or H2+CxHy gas mixtures were used. On the other hand, much lower density of stacking faults (SF) (<1 cm-2) was observed in the epilayer grown on the surface etched by only H2 gas. However, a high number of pits were generated in the epilayer grown on substrate etched by H2 only, which can be considered to be tradeoff of achieving low SF in epilayer by substrate etching. We also conclude from our experimental results that C rich surface is more favorable to generate SF in epilayer compared to Si rich surface.

The Vulcanization of Rubber with m-Dinitrobenzene

1938 ◽  
Vol 11 (1) ◽  
pp. 131-141
Author(s):  
J. M. Wright
Keyword(s):  
Chemical Reaction ◽  
Nitro Compound ◽  
Nitro Compounds ◽  
The Other ◽  
Vulcanized Rubber ◽  
Other Hand ◽  
Aging Properties ◽  
Original Report ◽  
Favorable Conditions ◽  
Better Than

Abstract The literature referring to the vulcanization of rubber with m-dinitrobenzene indicates the present undeveloped state of knowledge of the reaction and of the most favorable conditions for its employment. Much is vague and even contradictory. Ostromislensky (J. Russ. Phys.-Chem. Soc., 47, 1462 (1915)) stated that certain nitro compounds are capable of vulcanizing rubber in the absence of auxiliary substances, and that the products of vulcanization are superior in some respects to sulfur vulcanizates; tensile strengths obtained were comparable with those of sulfur vulcanizates; aging properties were found to be good; color and finish were better than those of sulfur vulcanizates. On the other hand, Porritt (J. Soc. Chem. Ind., 35, 986 (1916)), and Stevens (J. Soc. Chem. Ind., 36, 107 (1917)) failed to confirm these statements, but agreed that the presence of litharge is beneficial. Again in 1929, Ostromislensky (India Rubber World, 80, 55 (1929)) confirmed his original report, stating that he believed that this form of vulcanization is due to an action between rubber and the oxygen of the nitro compound. Blake (Ind. Eng. Chem., 22, 7 (1930)) stated that vulcanization of rubber with dinitrobenzene involves a monomolecular chemical reaction between rubber and dinitrobenzene, in which, of the 6 per cent dinitrobenzene, practically all of the nitrogen combined with the rubber. The end-product of the reaction appears to be a soft vulcanized rubber; no one has claimed to be able to produce an ebonite by the use of this reagent.

Phase Formations in Co/Si, Co/Ge, and Co/Si1−xGex by Solid Phase Reactions

1993 ◽  
Vol 320 ◽  
Author(s):  
Z. Wang ◽  
Y. L. Chen ◽  
H. Ying ◽  
R. J. Nemanich ◽  
D. E. Sayers
Keyword(s):  
Thin Films ◽  
Sheet Resistance ◽  
Epitaxial Layer ◽  
Annealing Temperature ◽  
Solid Phase ◽  
The Other ◽  
Other Hand ◽  
Solid Phase Reactions

ABSTRACTPhase formations in Co thin films (200Å in thickness) reacting with atomically clean Si(100), Ge(100), and Si0.80Ge0.20 epitaxial layer (800Å in thickness on Si(100) substrates) in UHV have been investigated. For the Co/Si system, it is found that CoSi (FeSi structure) is formed at 375°C through a very disordered CoSi phase, and the final CoSi2 phase is formed at 575°C. On the other hand, the Co5Ge7 phase was identified for the Co/Ge samples annealed at 300°C and 450°C and the final CoGe2 phase is formed at 600°C. For the Co/Si0.8 Ge0.20 samples annealed from 400°C to 600°C, Co(Si1−yGey) phases with y∼0.10 were detected, and for annealing at 700°C, only the CoSi2 phase was formed. These results indicate a preferential Co- Si reaction when annealing the Co/SiGe structure. It was also found that the sheet resistance of the reacted thin films depend strongly on annealing temperature.

scholarly journals Studying the Effect of Paracetamol Drug on the Conductivity of 0.5M Hydrochloric Acid Solution at Different Temperatures

2013 ◽  
Vol 11 (7) ◽  
pp. 2725-2745
Author(s):  
Hadi.Z. Al-Sawaad
Keyword(s):  
Activation Energy ◽  
Hydrochloric Acid ◽  
Acid Solution ◽  
Molar Conductance ◽  
Chloride Ions ◽  
The Other ◽  
Constant Concentration ◽  
Enthalpy Of Activation ◽  
Other Hand ◽  
Different Temperatures

In this study paracetamol drug is used to reduce the conductivity of 0.5M hydrochloric acid at different concentrations for each one of them at different temperatures ranged (30-60)°C. Generally , increasing of the concentration of  the inhibitor leads to reducing in conductivity of the acid at constant temperature. On the other hand, at constant concentration of  inhibitor, the conductivity is reduced as temperature increased i.e., paracetamol can adsorbed chemically on the metal or alloy. Furthermore the kinetic study of the molar conductance process reveal that in presence of paracetamol the activation energy and enthalpy of activation are negative compared with their values in absence of paracetamol where they are negative because the reducing the conductivity in presence of paracetamol where the non spontaneous property for the conductance of acid is increased as the paracetamol concentration increased in addition to increasing the negative value of entropy in presence of paracetamol that indicate to restrict for the mobility of hydrogen and chloride ions which correspond to 90.47% as efficiency of reducing the conductance of acid by paracetamol. On the other hand thermodynamic study is achieved which explained the adsorption of paracetamol obey to Freundlisch model. 

The Infrared Spectrum of Vulcanized Rubber and the Chemical Reaction between Rubber and Sulfur

1948 ◽  
Vol 21 (4) ◽  
pp. 799-800 ◽  
Author(s):  
N. Sheppard ◽  
G. B. M. Sutherland
Keyword(s):  
Infrared Spectrum ◽  
Physical Properties ◽  
Chemical Reaction ◽  
Spectroscopic Investigation ◽  
The Other ◽  
Characteristic Absorption ◽  
Vulcanized Rubber ◽  
Other Hand ◽  
Infrared Spectroscopic

Abstract In an earlier paper we described an infrared spectroscopic investigation of the vulcanization of rubber, and drew attention to a band at 10.4 µ (960 cm.−1) which appeared in the spectrum of both straight and accelerated vulcanization. We have investigated further this phenomenon, and find that the intensity of this band correlates well with the proportion of sulfur chemically incorporated, but not with the degree of vulcanization as reflected in the physical properties of the finished product. We were unable to explain this band in a convincing manner in terms of C—S linkages, but more recently have found a band in the same position (10.4 µ) and another at 11.2 µ (890 cm.−1) in certain thermally degraded rubbers. Since in this case the two new bands are obviously due, respectively, to the development of new CHR:CHR′ and CRR′:CH2 groups, it seemed probable that the 10.4 µ band might also be caused by new groupings of the former type. An investigation of the spectrum of an ebonite (in which the rubber-sulfur reaction has been carried to an extreme) confirmed this idea. In this spectrum, absorptions in the region of 6 µ showed that a considerable number of bonds remained, but the characteristic absorption at 12.0 µ arising from CRR′: CHR″groups in rubber had largely disappeared. On the other hand, the band at 10.4 µ (although shifted to slightly longer wave lengths) had increased greatly in intensity.

A COMPARISON OF SOME SEASONAL AND TEMPERATURE-INDUCED CHANGES IN PEROMYSCUS: COLD RESISTANCE, METABOLISM, AND PELAGE INSULATION

1953 ◽  
Vol 31 (5) ◽  
pp. 528-534 ◽  
Author(s):  
J. S. Hart ◽  
O. Heroux
Keyword(s):  
Oxygen Consumption ◽  
Environmental Factors ◽  
Seasonal Changes ◽  
Cold Resistance ◽  
The Other ◽  
Deer Mice ◽  
Other Hand ◽  
Lower Oxygen ◽  
Different Temperatures ◽  
Induced Changes

The cold resistance of deer mice captured during the winter was greater than that of summer mice and was accompanied by a greater pelage insulation and a lower oxygen consumption at 1–2 °C. On the other hand, the enhanced cold resistance of deer mice previously acclimated to cold was not accompanied by differences in pelage insulation. Moreover, in white-footed mice previously acclimated to different temperatures, oxygen consumption was similar at 1–2 °C. These data indicate that the seasonal changes observed in Peromyscus are not identical to changes produced by acclimation in the laboratory. Environmental factors responsible for these differences are discussed.

Etude à basse température des largeurs et des déplacements des raies rovibrationnelles de la bande fondamentale de H35Cl comprimé par N2, O2, D2 et H2

1980 ◽  
Vol 58 (3) ◽  
pp. 318-324 ◽  
Author(s):  
J. P. Houdeau ◽  
M. Larvor ◽  
C. Haeusler
Keyword(s):  
Quantum Number ◽  
Satisfactory Agreement ◽  
Electrostatic Interactions ◽  
Rotational Quantum Number ◽  
The Other ◽  
Realistic Approach ◽  
Other Hand ◽  
Different Temperatures ◽  
And Shifts

Linewidths and shifts in the spectrum (v0→1 band) of H35Cl perturbed by N2, O2, D2, and H2 have been measured for different temperatures (at 298 and 163 K). The Sisam spectrometer resolution was 0.024 cm−1. The Anderson–Tsao–Curnutte theory has been applied to the linewidth calculations. For perturbation by N2 and O2, this approach is justified by the intensity of electrostatic interactions, and it leads to a satisfactory agreement with experiment, at least for lines of low rotational quantum number. On the other hand, the low value of H2 and D2 quadrupole leads to values of the optical diameter close to the kinetic diameter. A discussion shows then that a more realistic approach is needed in that case.[Journal translation]

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