Enhancement of Long-Wavelength Photoluminescence Due to Heat-Treatment in Si-Doped GaAs

1992 ◽  
Vol 262 ◽  
Author(s):  
M. Suezawa ◽  
A. Kasuya ◽  
Y. Nishina ◽  
K. Sumino
Keyword(s):  
Heat Treatment ◽  
Radiative Recombination ◽  
Room Temperature ◽  
Excitation Spectra ◽  
Long Wavelength ◽  
Heat Treated ◽  
Intense Luminescence ◽  
Si Doped

ABSTRACTHighly officient radiative recombination even at room temperature was found at a wavelength of about 1.3 μm in heat-treated Si-doped GaAs. The range of Si concentrations and the condition of heat-treatment to yield this intense luminescence were determined. Excitation spectra of the PL lines suggest that such PL lines are related to pairs of Si-donor and Si- acceptor and such pairs combined with gallium vacancies.

scholarly journals Влияние термообработки на электрические характеристики полуизолирующих слоев, полученных с помощью облучения n-SiC высокоэнергетическими ионами аргона

2018 ◽  
Vol 44 (6) ◽  
pp. 11 ◽  
Author(s):  
П.А. Иванов ◽  
А.С. Потапов ◽  
М.Ф. Кудояров ◽  
М.А. Козловский ◽  
Т.П. Самсонова
Keyword(s):  
Heat Treatment ◽  
Silicon Carbide ◽  
Room Temperature ◽  
High Energy ◽  
Room Temperature Resistivity ◽  
Electrical Characteristics ◽  
Near Surface ◽  
Heat Treated ◽  
Argon Ions ◽  
Temperature Resistivity

AbstractIrradiation of crystalline n -type silicon carbide ( n -SiC) with high-energy (53-MeV) argon ions was used to create near-surface semi-insulating ( i -SiC) layers. The influence of subsequent heat treatment on the electrical characteristics of i -SiC layers has been studied. The most high-ohmic ion-irradiated i -SiC layers with room-temperature resistivity of no less than 1.6 × 10^13 Ω cm were obtained upon the heat treatment at 600°C, whereas the resistivity of such layers heat-treated at 230°C was about 5 × 10^7 Ω cm.

scholarly journals Hydrogen Detection with SAW Polymer/Quantum Dots Sensitive Films

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4481 ◽  
Author(s):  
Izabela Constantinoiu ◽  
Cristian Viespe
Keyword(s):  
Heat Treatment ◽  
Quantum Dots ◽  
Room Temperature ◽  
Limit Of Detection ◽  
Composite Films ◽  
High Specific Surface Area ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Heat Treated ◽  
Gas Molecules

Regarding the use of hydrogen as a fuel, it is necessary to measure its concentration in air at room temperature. In this paper, sensitive composite films have been developed for surface acoustic wave (SAW) sensors, using quantum dots (QDs) and polymers. Si/SiO2 QDs were used due to having a high specific surface area, which considerably improves the sensitivity of the sensors compared to those that only have a polymer. Si/SiO2 QDs were obtained by laser ablation and analyzed by X-ray diffraction and transmission electron microscopy (TEM). Two types of polymers were used: polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA). Polymer and polymer with QDs compositions were deposited on the sensor substrate by drop casting. A heat treatment was performed on the films at 80 °C with a thermal dwell of two hours. The sensors obtained were tested at different hydrogen concentrations at room temperature. A limit of detection (LOD) of 452 ppm was obtained by the sensor with PDMS and Si/SiO2 QDs, which was heat treated. The results demonstrated the potential of using QDs to improve the sensitivity of the SAW sensors and to achieve a heat treatment that increases its adsorption capacity of the gas molecules.

Platinum-TiO2 (Rutile) Substrate Interaction During Cyclic Oxidation-Reduction Heat-Treatment

1981 ◽  
Vol 39 ◽  
pp. 72-73
Author(s):  
S. Shinozaki ◽  
W. T. Donlon ◽  
A. H. Meitzler
Keyword(s):  
Heat Treatment ◽  
Room Temperature ◽  
Treatment Procedure ◽  
Substrate Interaction ◽  
Reducing Atmosphere ◽  
Oxidation Reduction ◽  
Heat Treated ◽  
Pt Electrodes ◽  
The Matrix ◽  
Tio2 Rutile

When polycrystalline TiO2 (rutile) pellets (∼1mm in thickness and ∼3 mm in diameter), dispersed with Pt particles to act as a catalyst, were heat-treated under certain conditions involving an applied electric field, new unusual microstructures were formed. The heat-treatment procedure was, as follows: 1) apply 1 volt dc field between two Pt electrodes inbedded into the pellet, 2) heat the sample to 750°C and begin cycling the sample between oxydizing (4% O2 in N2) and reducing (2% CO in N2) atmospheres at a rate of several cycles per hour, 3) lower the temperature to 600°C while continually cycling (200 cycle), and, 4) cool the sample to room temperature under the reducing atmosphere (1). The pellet was ion milled to a proper electron transparency and examined by means of a Siemens EM102 and a Philips EM400 TEM-STEM microscope.Some TiO2 grains in this sample exhibited no resolvable defect structure, except that the matrix appeared to be strained due to small defects (Fig. la).

THE EFFECT OF LOW TEMPERATURES UPON THE IMPACT RESISTANCE OF STEEL CASTINGS

1930 ◽  
Vol 2 (5) ◽  
pp. 327-340
Author(s):  
R. W. Moffatt
Keyword(s):  
Heat Treatment ◽  
Low Temperatures ◽  
Room Temperature ◽  
Freezing Point ◽  
High Carbon Steel ◽  
Impact Resistance ◽  
Nickel Steel ◽  
Heat Treated ◽  
Steel Castings ◽  
The Impact

The investigation deals with the effect of low temperatures on the impact resistance of steel castings and forgings. Low, medium and high carbon steel castings and a few alloys of vanadium, nickel, and vanadium-nickel steel castings were examined. The metals were subjected to low temperatures, both before and after heat treatment. The temperatures for the tests varied from room temperatures to temperatures well below 0° F., so as to extend below the ordinary atmospheric range of temperatures found in northern climates.It was found that the impact resistances of the metals decreased for temperatures below the freezing point. For specimens, not heat treated, the impact resistance at − 40° F. may be only one-third to one-half of that at room temperature. Heat treatment increases the impact resistance at room temperatures and temperatures below the freezing point. The impact resistance at − 40° F. for the heat-treated metal compared favorably with the impact resistance of the untreated metal at room temperature, 68° F. Heat treatment may slightly lower the yield point and the ultimate tensile strength, but it increases the ductility and the impact resistance of the metal. By proper heat treatment of steel castings the impact resistance at − 40° F. may be brought over 300% higher than that of the untreated metal at that temperature.

IN-SITU Analysis Of The Microstructure of Thermally Treated Thin Copper Films

1993 ◽  
Vol 309 ◽  
Author(s):  
J. Nucci ◽  
H. Neves ◽  
Y. Shacham ◽  
E. Eisenbraun ◽  
B. Zheng ◽  
...  
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Room Temperature ◽  
Thermal Evolution ◽  
Electron Beam Evaporation ◽  
Copper Films ◽  
Tem Analysis ◽  
Heat Treated ◽  
Baseline Information

AbstractCopper thin films were deposited by sputtering, electron beam evaporation, and electroless plating onto nitride membranes for TEM analysis. The samples were heat treated in-situ from room temperature to 600 °C for structural and chemical analysis. The as-deposited and heat treated microstructures were investigated. Orientation changes with heat treatment and reactions among the sample layers were analyzed by electron diffraction. This work provides baseline information for a study of the thermal evolution of copper lines.

Investigation on the Strain Behaviour of a Precipitation-Hardenable Aluminium Alloy through a Temperature Gradient Based Heat Treatment

2015 ◽  
Vol 639 ◽  
pp. 361-368 ◽  
Author(s):  
Gabriella di Michele ◽  
Pasquale Guglielmi ◽  
Gianfranco Palumbo ◽  
Donato Sorgente
Keyword(s):  
Heat Treatment ◽  
Temperature Gradient ◽  
Aluminium Alloy ◽  
Room Temperature ◽  
Tensile Tests ◽  
Gauge Length ◽  
Image Correlation ◽  
Experimental Campaign ◽  
Strain Behaviour ◽  
Heat Treated

In this work the strain behaviour of the heat-treated 6xxx series aluminium alloy AC170PX is investigated by a not conventional approach. Thanks to the low density combined with good mechanical properties, this aluminium alloy is often adopted for automotive applications. Despite these advantages, its formability at room temperature is low. In order to overcome this limit, a distribution of the material properties can be achieved by a local heat treatment (Tailored Heat Treated Blanks). In this context, to evaluate the effects of those parameters mainly affecting the precipitation hardening (aging temperature and aging time), a first experimental campaign was conducted using conventional furnace heat treatment in different conditions . Tensile tests were run with the aim of determining the flow and the aging curves of the heat treated specimens. Starting from these results, a not uniform heat treatment was designed using a Gleeble physical simulator Heat treatments based on a temperature gradient along the sample were performed. Then, tensile tests of the so heated specimens were carried out at room temperature. Through a digital image correlation system both the distribution and the evolution of the strain along the gauge length of the specimen were analysed in order to obtain the hardening/softening working conditions related to a specific heating cycle. These results were validated by the comparison with the data obtained from the first experimental campaign.

Influence of Heat Treatment on the Wear Behavior of a Haynes 282® Nickel-Based Superalloy

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Javier H. Ramírez-Ramírez ◽  
Juan Manuel Alvarado-Orozco ◽  
Francisco A. Pérez-González ◽  
Rafael Colás ◽  
Nelson F. Garza-Montes-de-Oca
Keyword(s):  
Heat Treatment ◽  
Room Temperature ◽  
Wear Behavior ◽  
Constant Load ◽  
Alloy Matrix ◽  
Nickel Based Superalloy ◽  
Heat Treated ◽  
Roll Wear ◽  
Sliding Distance ◽  
Wear Tests

Superalloys are metallic systems commonly used in components for aerospace and energy generation applications. In this paper, results of an investigation developed to analyze the effect of heat treatment on the wear behavior of a Haynes 282® superalloy under sliding, nonlubricated conditions are presented. Room temperature pin-on-roll wear tests were undertaken at a constant load and for a fixed sliding distance of 7.5 km. It was found that the wear rate of the alloys was greater for the heat treated specimens compared to the specimens that were tested in a cast and forged condition. Inspection of the alloys in both metallurgical conditions suggests that the wear phenomenon was characterized mostly by severe plastic deformation of the alloy matrix at both surface and subsurface regions by the well-known mechanism of plowing. The test specimens also experienced the formation of a tribofilm whose characteristics were different for each test condition. The formation of tribofilms also had a considerable influence on the wear behavior of the systems studied because they were also present on the surface of the counter rolls with this phenomenon being an additional wear mechanism experienced by the tribosystems studied.

Effects of a Thermal Coating Process on X100 UOE Line Pipe

2005 ◽  
Author(s):  
Chris Timms ◽  
Duane DeGeer ◽  
Martin McLamb
Keyword(s):  
Heat Treatment ◽  
Yield Strength ◽  
Room Temperature ◽  
High Strength ◽  
Economic Benefits ◽  
Slight Reduction ◽  
Strength Increase ◽  
Coating Process ◽  
Line Pipe ◽  
Heat Treated

The increased demand for high strength linepipe for onshore and offshore pipeline systems has been well documented over the past few years. The economic benefits have been demonstrated, and solutions have been developed to address the technical issues facing high strength linepipe use. However, there are still a few unanswered questions, one of which is addressed in this paper: what is the effect of thermal treatment during the pipeline coating process on the material behaviour of high strength linepipe? This paper presents the results of a thermal coupon study investigating the effects of low temperature heat treatment on the tensile and compressive stress strain curves of samples taken from X100 linepipe. Thirty axial test coupons and thirty circumferential test coupons were machined from a 52 inch diameter, 21 mm wall thickness UOE X100 linepipe. Some of the coupons were maintained in the as-received condition (no heat treatment) while others were heat-treated in a manner that simulates a coating plant induction heat treatment process. All coupons were subsequently tested in tension or compression, either at room temperature or at −18°C. This study has provided a number of interesting results. In regards to material strength, the heat treatment increased the tensile and compressive yield strengths in the longitudinal and circumferential coupons. Axial tensile, axial compressive and circumferential tensile yield strength increases ranged from 5 to 10%. Circumferential compressive yield strength increases ranged from 14 to 24%. A Y/T ratio increase of approximately 7% was observed for all heat-treated tensile coupons. The coupon tests conducted at −18°C were only slightly different than their room temperature counterparts; with an average yield strength increase of 4% in all directions and orientations and a slight reduction in Y/T ratio.

Effect of Heat Treatment Conditions and Small Addition of Cu on Occurrence of Serration in Al-Si Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 180-185
Author(s):  
Teruto Kanadani ◽  
Norihito Nagata ◽  
Keiyu Nakagawa ◽  
Koji Murakami ◽  
Makoto Hino
Keyword(s):  
Heat Treatment ◽  
Binary Alloy ◽  
Room Temperature ◽  
Small Addition ◽  
The Other ◽  
Aging Rate ◽  
Aging Period ◽  
Treatment Conditions ◽  
Heat Treated ◽  
Aging Conditions

In this study, the effect of heat treatment conditions and small addition of Cu on occurrence of serration in Al-Si alloys was investigated. Specimens were aged for various times up to 87ks at 273K or 473K after quenching from 853K, and tensile-tested at room temperature. In the binary alloy, serration was observed even after aging for 87ks at 273K, while in the case of aging at 473K, serration did not occur under aging conditions at aging time, tA≧20s. On the other hand, serration was observed even after aging for 72ks at 473K in the Cu-added alloy. In both alloys, serration was also recognized when the specimens were furnace-cooled from 853K to room temperature. Thus, for aging at 473K of the binary alloy serration was observed only when the aging period was short enough, but addition of Cu to the binary alloy prolonged the aging period where serration could be recognized. Aging rate of both alloys measured by tensile strength was almost the same. The size of precipitates in the Cu-added alloy was smaller than that in binary alloy. Moreover, the number of the precipitates at the grain boundary in the Cu-added alloy was smaller than that in the binary alloy. It is considered that serration occurs for Al-Si alloys when the specimen is heat-treated so that small precipitates may be formed. Now the details of the effect of Cu addition are not clear.

Mechanical and Electrical Properties of Heat-Treated Ladder Polymer Fiber

1992 ◽  
Vol 247 ◽  
Author(s):  
C. S. Wang ◽  
C. Y-C Lee ◽  
F. E. Arnold
Keyword(s):  
Heat Treatment ◽  
Room Temperature ◽  
Polyphosphoric Acid ◽  
Methanesulfonic Acid ◽  
Charge Carriers ◽  
Polymer Fiber ◽  
Mechanical And Electrical Properties ◽  
Heat Treated ◽  
Ladder Polymer ◽  
Enhanced Conductivity

ABSTRACTThe ladder polymer poly[(7-oxo-7H, 10H-benz(d, e)imidazo(4', 5':5, 6)-benzimidazo(2, l-a)isoquinoline-3, 4:10, ll-tetrayl)-10-carbonyl] (BBL) was synthesized in polyphosphoric acid (PPA) at a concentration of 15% by weight. The polymer had an intrinsic viscosity of 8.75 dl/g in methanesulfonic acid (MSA) at 30°C. Highly oriented BBL fiber was spun by a dry-jet wet-spin process with a spin-draw-ratio of 8 to 1. After neutralization, the fiber exhibited a phosphoms content below the detectable limit (0.04%) by elemental analysis. This fiber, after a heat treatment at 300°C for 30 seconds under tension, showed a Young's modulus of 120 GPa, a tensile strength of 830 MPa and a compressive strength of 410 MPa. The fiber was also heat-treated at temperatures from 100°C to 600°C at 50°C increments for electrical conductivity measurements. It was found that room temperature DC conductivity of the BBL fiber increased dramatically from 2×10−8 S/cm with 100°C heat treatment to 3×10−4 S/cm with 350°C heat treatment and then decreased to 6×10−7 S/cm with 600°C heat treatment. The enhanced conductivity of heat-treated BBL fiber is believed due to the improved structural order in the BBL fiber and the thermally excited charge carriers.

Sign in / Sign up

Export Citation Format

Share Document