Formation of Long Wavelength InP Laser MESAS

1993 ◽  
Vol 300 ◽  
Author(s):  
F. Ren ◽  
S. J. Pearton ◽  
B. Tseng ◽  
J. R. Lothian ◽  
C. Constantine
Keyword(s):  
Elevated Temperature ◽  
Etch Rate ◽  
Room Temperature ◽  
Plasma Chemistry ◽  
Dry Etching ◽  
Pattern Transfer ◽  
Process Step ◽  
Long Wavelength ◽  
Low Degree ◽  
Etched Surface

ABSTRACTNarrow (1 μm), deep (3.5 μm) laser mesas have been formed on 2”φ InP wafers using stepper lithography and dry etching techniques for both dielectric and semiconductor patterning. Contrast enhancement techniques produce excellent edge acuity and vertical sidewalls on the initial photoresist lines. Pattern transfer to the underlying SiO2 regrowth mask is achieved by ECR SF6/Ar dry etching at 1 mTorr and –100V, conditions which also retain the verticality of the mesa. The semiconductor is etched using an ECR Cl2/CH4/H2/Ar discharge at 0.3 mTorr and –80V, with the sample held at ∼ 150°C. The etch rate under these conditions is ∼1 μm/min, with a selectivity of ≥10:1 for the semiconductor over the dielectric mask. The smooth etched surface and low degree of damage make this process ideal for epitaxial regrowth. The uniformity of each process step is also acceptable (≤7%). Comparison of the elevated temperature Cl2/CH4/H2/Ar mixture with the more conventional room temperature CH4/H2 plasma chemistry will be given.

Elevated Temperature Reactive Ion Etching of GaAs and AIGaAs in C2H6 / H2

1989 ◽  
Vol 158 ◽  
Author(s):  
S. J. Pearton ◽  
W. S. Hobson ◽  
K. S. Jones
Keyword(s):  
Elevated Temperature ◽  
Surface Morphology ◽  
Temperature Dependence ◽  
Etch Rate ◽  
Reactive Ion Etching ◽  
Atomic Composition ◽  
Hydrogen Passivation ◽  
Ion Etching ◽  
Polymer Deposition ◽  
Etched Surface

ABSTRACTThe temperature dependence of etch rate, surface morphology and atomic composition, and depth of hydrogen passivation of Si dopants in n-type GaAs and AIGaAs has been measured for reactive ion etching in C2H6 /H2. The etching of GaAs shows an increase of a factor of two between 150 and 250°C, decreasing at higher temperatures, while there is no temperature dependence for the etch rate of AlGaAs over the range 50-350°C. The As-to-Ga ratio in the nearsurface region of GaAs remains unchanged over the whole temperature range investigated and there is no polymer deposition. The etched surface morphology is smooth for both GaAs and AIGaAs for all temperatures while the depth of Si dopant passivation by hydrogen shows an increase with increasing substrate temperature during the etching treatment.

Cl2-Based Dry Etching Of The AIGaInN System In Inductively Coupled Plasmas

1997 ◽  
Vol 483 ◽  
Author(s):  
Hyun Cho ◽  
C. B. Vartuli ◽  
C. R. Abernathy ◽  
S. M. Donovan ◽  
S. J. Pearton ◽  
...  
Keyword(s):  
Surface Morphology ◽  
Systematic Study ◽  
Etch Rate ◽  
Dry Etching ◽  
The Other ◽  
Pattern Transfer ◽  
Inductively Coupled Plasmas ◽  
Source Power ◽  
Inductively Coupled ◽  
Coupled Plasmas

AbstractCl2-based Inductively Coupled Plamas with low additional dc self-biases(−100V) produce convenient etch rates(500–1500Å.min−1) for GaN, AIN, InN, InAiN and InGaN. A systematic study of the effects of additive gas(Ar, N2, H2), discharge composition and ICP source power and chuck power on etch rate and surface morphology has been performed. The general trends are to go through a maximum in etch rate with percent C12 in the discharge for all three mixtures, and to have an increase(decrease) in etch rate with source power(pressure). Since the etching is strongly ion-assisted, anisotropic pattern transfer is readily achieved. Maximum etch selectivities of approximately 6 for InN over the other nitrides were obtained.

scholarly journals Joint analysis of the magnetic field and Total Gradient Intensity in Central Europe

2019 ◽  
Author(s):  
Maurizio Milano ◽  
Maurizio Fedi ◽  
J. Derek Fairhead
Keyword(s):  
Magnetic Field ◽  
Central Europe ◽  
Joint Analysis ◽  
East European ◽  
Long Wavelength ◽  
Low Degree ◽  
Total Gradient ◽  
Synthetic Models ◽  
The Magnetic Field ◽  
Different Altitudes

Abstract. In the European region, the magnetic field at satellite altitudes (~ 350 km) is mainly defined by a long-wavelength magnetic-low called here the Central Europe Magnetic Low (CEML), located to the southwest of the Trans European Suture Zone (TESZ). We studied this area by a joint analysis of the magnetic and total gradient (∇T) anomaly maps, for a range of different altitudes of 5 km, 100 km and 350 km. Tests on synthetic models showed the usefulness of the joint analysis at various altitudes to identify reverse dipolar anomalies and to characterize areas in which magnetization is weak. By this way we identified areas where either reversely or normally magnetized sources are locally dominant. At a European scale these anomalies are sparse, with a low degree of coalescence effect. The ∇T map indeed presents generally small values within the CEML area, indicating that the Palaeozoic Platform is weakly magnetized. At 350 km altitude, the TESZ effect is largely dominant: with intense ∇T highs above the East European Craton (EEC) and very small values above the Palaeozoic Platform, this again denoting a weakly magnetized crust. Small coalescence effects are masked by the trend of the TESZ. Although we identified sparsely located reversely magnetized sources in the Palaeozoic Platform of the CEML, the joint analysis does not support a model of a generally reversely magnetized crust. Instead, our analysis strongly favors the hypothesis that the CEML anomaly is mainly caused by a sharp contrast between the magnetic properties of EEC and Palaeozoic Platform.

The Static Mechanical Property of Concrete at Elevated Temperature

2011 ◽  
Vol 261-263 ◽  
pp. 212-216
Author(s):  
Jun Lin Tao ◽  
Li Bo Qin ◽  
Kui Li ◽  
Bin Jia
Keyword(s):  
Mechanical Property ◽  
Elevated Temperature ◽  
Room Temperature ◽  
Critical Strain ◽  
Plain Concrete ◽  
Constitutive Relationship ◽  
Heating Method ◽  
Experiment System ◽  
Wave Heating ◽  
Static Mechanical

Using micro-wave heating method, the previous disadvantages of heating slowly and non-uniform are broken through. And plain concrete high temperature loading experiment system is composed of the method and material experiment machine. Many experiments of self-made concrete are carried out from room temperature to 600°C by this system. The strength and critical strain of concrete with temperature are obtained, and through analysis of the compressive stress-strain curves under different temperature, the constitutive relationship is established. The result shows that this constitutive relationship is greatly agrees with experiment. Meanwhile, the phenomenon is analyzed and explained in the progress of experiment.

Effects of Elevated Temperatures on the Compressive Strength of HFCC

2011 ◽  
Vol 261-263 ◽  
pp. 416-420 ◽  
Author(s):  
Fu Ping Jia ◽  
Heng Lin Lv ◽  
Yi Bing Sun ◽  
Bu Yu Cao ◽  
Shi Ning Ding
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Fly Ash ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Relative Strength ◽  
Ordinary Concrete ◽  
Residual Compressive Strength ◽  
Fly Ash Concrete ◽  
The Relationship

This paper presents the results of elevated temperatures on the compressive of high fly ash content concrete (HFCC). The specimens were prepared with three different replacements of cement by fly ash 30%, 40% and 50% by mass and the residual compressive strength was tested after exposure to elevated temperature 250, 450, 550 and 650°C and room temperature respectively. The results showed that the compressive strength apparently decreased with the elevated temperature increased. The presence of fly ash was effective for improvement of the relative strength, which was the ratio of residual compressive strength after exposure to elevated temperature and ordinary concrete. The relative compressive strength of fly ash concrete was higher than those of ordinary concrete. Based on the experiments results, the alternating simulation formula to determine the relationship among relative strength, elevated temperature and fly ash replacement is developed by using regression of results, which provides the theoretical basis for the evaluation and repair of HFCC after elevated temperature.

Invited Paper Dry Etching Of Indium Phosphide At Room Temperature

1985 ◽  
Author(s):  
G. F. Doughty ◽  
C. L. Dargan ◽  
C. D. W. .. Wilkinson
Keyword(s):  
Indium Phosphide ◽  
Room Temperature ◽  
Dry Etching

High-power long-wavelength room-temperature MOVPE-grown quantum cascade lasers with air-semiconductor waveguide

2008 ◽  
Vol 44 (8) ◽  
pp. 525 ◽  
Author(s):  
Q.J. Wang ◽  
C. Pflügl ◽  
L. Diehl ◽  
F. Capasso ◽  
S. Furuta ◽  
...  
Keyword(s):  
High Power ◽  
Room Temperature ◽  
Quantum Cascade Lasers ◽  
Long Wavelength ◽  
Quantum Cascade ◽  
Cascade Lasers

Phase Relationship Studies of Silicon Nitride System—A Key to Materials Design

1992 ◽  
Vol 287 ◽  
Author(s):  
T.S. Yen ◽  
W.Y. Sun
Keyword(s):  
Elevated Temperature ◽  
Silicon Nitride ◽  
Grain Boundary ◽  
Phase Behavior ◽  
Phase Diagrams ◽  
Room Temperature ◽  
Phase Relationship ◽  
Materials Design ◽  
Basic Approach ◽  
System A

ABSTRACTAdditions and revisions to several of the most important phase diagrams and phase behavior diagrams in the silicon nitride field are reviewed in this work, with emphasis on the Y-Si-A1-O-N system. This information is further used to make observations on the promising silicon nitride systems containing either highly refractory grain boundary phases or compatible matrix phases of desirable properties. Examples are provided to illustrate the advantage of such a basic approach to materials design. Hardness, toughness, strength at room temperature and elevated temperature and even sinterability can all be improved by adopting such an approach.

Surface Structures of Phosphorus and Indium on Si(111)

1998 ◽  
Vol 05 (01) ◽  
pp. 69-76
Author(s):  
F. P. Netzer ◽  
L. Vitali ◽  
J. Kraft ◽  
M. G. Ramesy
Keyword(s):  
Elevated Temperature ◽  
Room Temperature ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Low Energy Electron Diffraction ◽  
Diffusion Limited ◽  
Lower Terrace ◽  
Surface Reconstructions ◽  
Low Energy Electron ◽  
Stm Images

The interaction of vapor phase P2 with the [Formula: see text] monolayer surface at room temperature and elevated temperature has been monitored by scanning tunneling microscopy (STM) and spectroscopy (STS) in conjunction with Auger electron spectroscopy and low-energy electron diffraction (LEED). The surface rection can be readily followed by STM because of the very different contrast of the reacted areas in the STM images. The reaction develops around overlayer defects at room temperature and appears to be diffusion-limited, whereas at 300°C the reaction is initiated at the step edges, from which the reaction front progresses onto the lower terrace areas. At elevated temperature several ordered surface reconstructions, showing different STS fingerprints, are detected on the P–In/Si(111) surfaces, which are associated tentatively with P- and Si-terminated structures and an ordered InP phase.

Thermal Resistance of Fly Ash Geopolymers with Alumina as Additive

2018 ◽  
Vol 281 ◽  
pp. 182-188
Author(s):  
Yong Sing Ng ◽  
Yun Ming Liew ◽  
Cheng Yong Heah ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Kamarudin Hussin
Keyword(s):  
Elevated Temperature ◽  
Fly Ash ◽  
Thermal Resistance ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Room Temperature ◽  
Strength Degradation ◽  
Alumina Addition ◽  
Higher Temperature ◽  
Temperature Exposure

The present work investigates the effect of alumina addition on the thermal resistance of fly ash geopolymers. Fly ash geopolymers were synthesised by mixing fly ash with activator solution (A mixture of 12M sodium hydroxide and sodium silicate) at fly ash/activator ratio of 2.5 and sodium silicate/sodium hydroxide ratio of 2.5. The alumina (0, 2 and 4 wt %) was added as an additive. The geopolymers were cured at room temperature for 24 hours and 60°C for another 24 hours. After 28 days, the geopolymers was heated to elevated temperature (200 - 1000°C). For unexposed geopolymers, the addition of 2 wt % of alumina increased the compressive strength of fly ash geopolymers while the strength decreased when the content increased to 4 wt.%. The temperature-exposed geopolymers showed enhancement of strength at 200°C regardless of the alumina content. The strength reduced at higher temperature exposure (> 200°C). Despite the strength degradation at elevated temperature, the strength attained was relatively high in the range of 13 - 45 MPa up to 1000°C which adequately for application as structural materials.

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