| 1. |
- Aamodt, K., et al.
(author)
-
The ALICE experiment at the CERN LHC
- 2008
-
In: Journal of Instrumentation. - 1748-0221. ; 3:S08002
-
Research review (peer-reviewed)abstract
- ALICE (A Large Ion Collider Experiment) is a general-purpose, heavy-ion detector at the CERN LHC which focuses on QCD, the strong-interaction sector of the Standard Model. It is designed to address the physics of strongly interacting matter and the quark-gluon plasma at extreme values of energy density and temperature in nucleus-nucleus collisions. Besides running with Pb ions, the physics programme includes collisions with lighter ions, lower energy running and dedicated proton-nucleus runs. ALICE will also take data with proton beams at the top LHC energy to collect reference data for the heavy-ion programme and to address several QCD topics for which ALICE is complementary to the other LHC detectors. The ALICE detector has been built by a collaboration including currently over 1000 physicists and engineers from 105 Institutes in 30 countries, Its overall dimensions are 16 x 16 x 26 m(3) with a total weight of approximately 10 000 t. The experiment consists of 18 different detector systems each with its own specific technology choice and design constraints, driven both by the physics requirements and the experimental conditions expected at LHC. The most stringent design constraint is to cope with the extreme particle multiplicity anticipated in central Pb-Pb collisions. The different subsystems were optimized to provide high-momentum resolution as well as excellent Particle Identification (PID) over a broad range in momentum, up to the highest multiplicities predicted for LHC. This will allow for comprehensive studies of hadrons, electrons, muons, and photons produced in the collision of heavy nuclei. Most detector systems are scheduled to be installed and ready for data taking by mid-2008 when the LHC is scheduled to start operation, with the exception of parts of the Photon Spectrometer (PHOS), Transition Radiation Detector (TRD) and Electro Magnetic Calorimeter (EMCal). These detectors will be completed for the high-luminosity ion run expected in 2010. This paper describes in detail the detector components as installed for the first data taking in the summer of 2008.
|
|
| 2. |
- Manavaimaran, Balaji, et al.
(author)
-
Influence of initial growth stages on AlN epilayers grown by metal organic chemical vapor deposition
- 2015
-
In: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 414, s. 69-75
-
Journal article (peer-reviewed)abstract
- AIN layers of thickness of about 2 mu m have been grown with AIN nucleation layers (NLs) on (001) sapphire substrates using metal organic chemical vapor deposition. Increasing the AlN-NL deposition temperature from 850 to 1250 degrees C has been found to have significant effect on the surface morphology and the structural quality of the AIN layers. The surface morphology of the AlN-NLs and the AIN layers has been assessed using atomic force microscopy (AFM). The AM images of the AlN-NLs reveal the coalescence pattern of NLs. AM images of the AlN layers and the in-situ reflectance measurement disclose the surface morphology and the growth pattern of the AIN layers, respectively. Smooth surface with macro-steps and terrace features has been achieved for the AIN layer grown on the NL deposited at 950 degrees C. The structural quality of AIN layers has been studied by high resolution X-ray diffraction and Raman spectroscopy. The screw dislocation density from (002) reflection and the average edge dislocation density from (102), (302) and (100) reflections of the AIN layer on NL deposited at 950 degrees C are estimated to be 9 x 10(7) cm(-2) and 4.4 x 10(9) cm(-2), respectively. Lateral correlation length (L) is calculated from the (114) reciprocal space mapping of the AIN layers and correlated with the edge dislocation density of the AIN layers. Raman E-2 (high) phonon mode indicates compressive strain in the AIN layers grown on the NLs deposited at various temperatures. From this work, it has been inferred that the uniform coalescence of the nucleation islands and the complete coverage of AlN-NL determine the surface morphology and the structural quality of the subsequently grown AIN layers.
|
|
| 3. |
- Baskar, K., et al.
(author)
-
Surface morphology and localised states of GaInNAs single quantum wells grown by MOVPE
- 2003
-
In: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 248, s. 431-436
-
Journal article (peer-reviewed)abstract
- GaInNAs/GaAs single quantum wells (QWs) have been grown by metalorganic vapour phase epitaxy (MOVPE). The surface morphology has been studied by atomic force microscopy (AFM). The density of pits observed on the surface of QW structures was found to depend on the growth temperature and dimethylhydrazine (DMHy) flow. Cross-sectional AFM image showed the presence of defects at the interface of GaInNAs/GaAs. The low temperature photoluminescence characteristics of the QWs as a function of growth temperature. DMHy flow and density of surface pits have been discussed. The origin of pit formation is addressed based on the pyrolysis products present during the growth of QWs. The results suggest that higher growth temperature maybe desirable to obtain good quality GaInNAs QWS.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Mogg, S., et al.
(author)
-
High-performance 1.2-ÎŒm Highly strained InGaAs/GaAs quantum well lasers
- 2002
-
In: Conference Proceedings - International Conference on Indium Phosphide and Related Materials. - Stockholm. ; , s. 107-110
-
Conference paper (peer-reviewed)abstract
- The growth and characterisation of high-performance 1.2-Όm highly strained InGaAs/GaAs single quantum well (SQW) laser diodes is reported. High output power in excess of 200 mW per facet was obtained from ridge-waveguide (RWG) lasers at an emission wavelength of 1230 nm. These lasers operate CW to at least 145°C and show a high characteristic temperature of 150 K. The net modal gain was measured using the method described by Hakki and Paoli.
|
|
| 7. |
- Mogg, Sebastian, et al.
(author)
-
High-performance 1.2- mu;m highly strained InGaAs/GaAs quantum well lasers
- 2002
-
In: Indium Phosphide and Related Materials Conference, 2002. IPRM. 14th. ; , s. 107-110
-
Conference paper (peer-reviewed)abstract
- The growth and characterisation of high-performance 1.2- mu;m highly strained InGaAs/GaAs single quantum well (SQW) laser diodes is reported. High output power in excess of 200 mW per facet was obtained from ridge-waveguide (RWG) lasers at an emission wavelength of 1230 nm. These lasers operate CW to at least 145 deg;C and show a high characteristic temperature of 150 K. The net modal gain was measured using the method described by Hakki and Paoli (1975).
|
|
| 8. |
- Nagarajan, Mony, et al.
(author)
-
Growth of Zn3As2 on GaAs by liquid phase epitaxy and their characterization
- 2011
-
In: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 314:1, s. 119-122
-
Journal article (peer-reviewed)abstract
- Zn3As2 epitaxial layers were grown on GaAs (1 0 0) substrates by liquid phase epitaxy (LPE) using Ga as the solvent. Zinc mole fraction in the growth melt was varied from 1.07 x 10(-2) to 6 x 10(-2). X-ray diffraction spectrum exhibits a sharp peak at 43.3 degrees characteristic of Zn3As2 crystalline layer. The peak intensity increases with increase in zinc mole fraction in the growth melt. The compositions of the as-grown Zn3As2 layers were confirmed by energy dispersive X-ray (EDX) analysis. Surface morphology was studied using scanning electron microscopy (SEM) and the thickness of the epilayers was also determined. The Hall measurements at 300 K indicate that Zn3As2 epilayers are unintentionally p-doped. With an increase of zinc mole fraction in the growth melt, carrier concentration increases and carrier mobility decreases. Infrared optical absorption spectroscopy showed a sharp absorption edge at 1.0 eV corresponding to the reported band gap of Zn3As2. (C) 2010 Elsevier B.V. All rights reserved.
|
|
| 9. |
- Sudhakar, S., et al.
(author)
-
Irradiation induced nanotrack and property modification in Zn 3P 2
- 2012
-
In: Physica Status Solidi. C, Current topics in solid state physics. - : Wiley. - 1610-1634 .- 1610-1642. ; 9:7, s. 1636-1639
-
Journal article (peer-reviewed)abstract
- Zn 3P 2 epilayers were grown on InP (100) substrates by liquid phase epitaxy (LPE) using In solvent. Zinc composition in the epilayers was varied by changing the zinc mole fraction in the growth melt and was confirmed by energy dispersive X-ray analysis (EDAX). Stoichiometric Zn 3P 2 epilayers were subjected to 100 MeV Ni ion irradiation with various ion fluences of 1 × 10 10 to 1 × 10 13 ions/cm 2 at 77 K. From the high resolution X-ray diffraction (HRXRD) of 100 MeV Ni ion irradiated epilayers, the decrease in the peak intensities and increase in the FWHM values were observed. AFM analysis revealed the formation of nanotracks in the irradiated Zn 3P 2 epilayers. Hall measurements showed the decrease in carrier mobility with the increase of ion fluence. The absorption band edge of Zn 3P 2 gradually decreased from 1.49 eV to 1.42 eV upon increasing the ion fluence.
|
|
| 10. |
|
|
| 11. |
- Sun, Y. T., et al.
(author)
-
Thermal strain in indium phosphide on silicon obtained by epitaxial lateral overgrowth
- 2003
-
In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 94:4, s. 2746-2748
-
Journal article (peer-reviewed)abstract
- High-resolution x-ray diffraction reciprocal lattice mapping and low-temperature photoluminescence (PL) were used to study the thermal strain in InP layers grown on Si (001) substrate by hydride vapor-phase epitaxial lateral overgrowth (ELO) technique. Good agreement is found between the PL and x-ray measurements. We show that strain in the grown ELO InP/Si layers is affected by the aspect ratio (width to height ratio) of the ELO InP layer. Almost strain-free InP layer with high crystallographic quality is obtained on Si substrate, which is similar to that of a homoepitaxial InP layer.
|
|
| 12. |
- Sundgren, P., et al.
(author)
-
Morphological instability of GaInNAs quantum wells on AlGaAs/GaAs distributed bragg reflectors grown by metal-organic vapor-phase epitaxy
- 2002
-
In: Conference Proceedings - International Conference on Indium Phosphide and Related Materials. - Stockholm. ; , s. 241-244
-
Conference paper (peer-reviewed)abstract
- We report on the optical and structural integrity of metal-organic vapor-phase epitaxy grown GaInNAs/GaAs single quantum wells on AlGaAs/GaAs distributed Bragg reflectors (DBRs). Surface morphology as measured by atomic force microscopy and quantum well photoluminescence were investigated for different numbers of DBR periods and different DBR-growth temperatures. Increased number of DBR periods severely degrades the surface morphology and photoluminescence. However, a significant improvement was obtained by lowering the growth temperature of the DBRs from 745 to 680°C.
|
|
| 13. |
- Suresh, S., et al.
(author)
-
Studies on the effect of ammonia flow rate induced defects in gallium nitride grown by MOCVD
- 2010
-
In: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 312:21, s. 3151-3155
-
Journal article (peer-reviewed)abstract
- Gallium nitride (GaN) epitaxial layers were grown with different V/III ratios by varying the ammonia (NH3) flow rate, keeping the flow rate of the other precursor, trimethylgallium (TMG), constant, in an MOCVD system. X-ray rocking curve widths of a (1 0 2) reflection increase with an increase in V/III ratio while the (0 0 2) rocking curve widths decrease. The dislocation density was found to increase with an increase in ammonia flow rate, as determined by hot-wet chemical etching and atomic force microscopy. 77K photoluminescence studies show near band emission at 3.49 eV and yellow luminescence peaking at 2.2 eV. The yellow luminescence (YL) intensity decreases with an increase in V/III ratio. Positron annihilation spectroscopy studies show that the concentration of Ga-like vacancies increases with an increase in ammonia flow rate. This study confirms that the yellow luminescence in the GaN arises due to deep levels formed by gallium vacancies decorated with oxygen atoms.
|
|
