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- Alcorn, J, et al.
(författare)
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Basic instrumentation for Hall A at Jefferson Lab
- 2004
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 522:3, s. 294-346
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Tidskriftsartikel (refereegranskat)abstract
- The instrumentation in Hall A at the Thomas Jefferson National Accelerator Facility was designed to study electro-and photo-induced reactions at very high luminosity and good momentum and angular resolution for at least one of the reaction products. The central components of Hall A are two identical high resolution spectrometers, which allow the vertical drift chambers in the focal plane to provide a momentum resolution of better than 2 x 10(-4). A variety of Cherenkov counters, scintillators and lead-glass calorimeters provide excellent particle identification. The facility has been operated successfully at a luminosity well in excess of 10(38) CM-2 s(-1). The research program is aimed at a variety of subjects, including nucleon structure functions, nucleon form factors and properties of the nuclear medium. (C) 2003 Elsevier B.V. All rights reserved.
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| 2. |
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| 3. |
- Lu, W., et al.
(författare)
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Application of combinatorial material chip method on the improvement of quantum dots emission efficiency
- 2004
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Ingår i: Proceedings of the SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 5277:1, s. 99-108
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Konferensbidrag (refereegranskat)abstract
- The combinatorial material chip method has been used to study the emission efficiency of InAs/GaAs quantum dots. The photoluminescence spectroscopy is performed to obtain the rule of emission efficiency on the proton implantation dose. A pronounced enhancement of room temperature emission efficiency has been obtained by the optimized quantum dots process condition. The increment of emission efficiency up to 80 itmes has been observed. This effect may be resulted from both the proton passivation and carrier capture enhancement effects. The maximum photoluminescence peak shift is about 23 meV resulted from the intermixing of quantum dots. A linear dependence behavior has been observed for both the non-radiative recombination time and carrier relaxation time on the ion-implantation dose. The maximum enhancement of the photoluminescence is observed in the proton implantation dose of 1.0 x 1014 cm-2 followed by rapid thermal annealing at 700°C. These effects will be useful for the QDs' optoelectronic devices.
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| 5. |
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| 6. |
- Zhao, Q.X., et al.
(författare)
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Dynamic properties of radiative recombination in p-type d-doped layers in GaAs
- 2001
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 63
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Tidskriftsartikel (refereegranskat)abstract
- We present an optical study of thin Zn-doped GaAs layers embedded in bulk GaAs, grown by metal-organic vapor-phase-epitaxy by means of stationary and time-resolved optical spectroscopy. The concentration of the Zn acceptors was aimed at 2×1020/cm3 in 4-nm-wide doping regions. The intensity of the optical radiative transition (so called the F emission) appearing in photoluminescence spectra was found to be related to holes confined at doping regions. The F emission shows a strong dependence on excitation intensity and temperature. The energy position varies from 1.46 to 1.49 eV as the excitation density changes from about 40 mW/cm2 to 23 W/cm2. The dynamic properties of the F-emission band have been studied by time-resolved spectroscopy. The F emission shows a nonexponential decay character. The decay time of the F emission exhibits a strong dependence on the detection energy within the F-emission band. The decay time becomes longer as the detection energy is redshifted.
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