Investigation of Sidewall Recombination in GaN Using a Quantum Well Probe

2000 ◽  
Vol 639 ◽  
Author(s):  
E. D. Haberer ◽  
M. Woods ◽  
A. Stonas ◽  
C-H. Chen ◽  
S. Keller ◽  
...  
Keyword(s):  
Quantum Well ◽  
Preliminary Data ◽  
Room Temperature ◽  
Spot Size ◽  
Excitation Source ◽  
Laser Spot Size ◽  
Room Temperature Photoluminescence ◽  
Size Dependent ◽  
Before And After ◽  
Pl Intensity

ABSTRACTIn this study, we use a quantum well (QW) probe structure to explore the size dependent effects of sidewall recombination in GaN. Mesas 0.8-7 μm in width with pitches of 4 μm, 8 μm, and 12 μm were etched into the QW probe structure, exposing the QW at the sidewalls. Several etch conditions were investigated. Room temperature photoluminescence (PL) measurements, using a He-Cd laser as an excitation source and laser spot size of approximately 230 μm, were taken before and after the mesas were etched. The effects of sidewall formation were quantified by comparing the maximum PL intensity of the QW before and after etch. Higher remaining PL intensity was observed for etch conditions which used both Ar ions and Cl2 gas instead of only Ar ions. The fraction of remaining PL decreased with decreasing mesa width, however the remaining PL intensity was relatively large even for small features. The preliminary data suggested that GaN is relatively insensitive to sidewall damage.

Degradation in a Methyl-phenyl Co-Polymeric Polysilane for LED Applications

2003 ◽  
Vol 769 ◽  
Author(s):  
Asha Sharma ◽  
Deepak ◽  
Monica Katiyar ◽  
Satyendra Kumar ◽  
V. Chandrasekhar ◽  
...  
Keyword(s):  
Thin Films ◽  
Molecular Weight ◽  
Light Source ◽  
Room Temperature ◽  
Light Exposure ◽  
Room Temperature Photoluminescence ◽  
Pl Spectrum ◽  
Pl Intensity ◽  
Methyl Phenyl

AbstractThe optical degradation of polysilane copolymer has been studied in spin cast thin films and solutions using light source of 325 nm wavelength. The room temperature photoluminescence (PL) spectrum of these films show a sharp emission at 368 nm when excited with a source of 325 nm. However, the PL intensity deteriorates with time upon light exposure. Further the causes of this degradation have been examined by characterizing the material for its transmission behaviour and changes occurring in molecular weight as analysed by GPC data.

scholarly journals Фотоиндуцированная обратимая локальная деформация рельефа поверхности в объемных монокристаллах TlInSe-=SUB=-2-=/SUB=-, TlGaTe-=SUB=-2-=/SUB=- и TlSe

2018 ◽  
Vol 44 (14) ◽  
pp. 86
Author(s):  
Y.G. Shim ◽  
T. Asahi ◽  
K. Wakita ◽  
Н.Т. Мамедов ◽  
Е.Н. Алиева ◽  
...  
Keyword(s):  
Laser Radiation ◽  
Room Temperature ◽  
Surface Deformation ◽  
Damage Threshold ◽  
Spot Size ◽  
Photon Absorption ◽  
Laser Radiation Intensity ◽  
Laser Spot Size ◽  
Absorption Length ◽  
Bulk Single Crystals

AbstractGiant macroscopic expansion of the surface relief, localized within a laser spot size, has been observed in bulk single crystals of TlInSe_2, TlGaTe_2, and TlSe at room temperature and laser radiation densities lower by at least two orders of magnitude than the material optical damage threshold. Quantitative estimations of the deformation magnitude in this local region were obtained using an interference dilatometer. The photon absorption length was determined with the aid of spectroscopic ellipsometry. It is established that the surface deformation amounts to 2.6 × 10^–3 at a laser radiation intensity of 19 mW/mm^2. The observed phenomenon has a thermal nature and is probably related to a low thermal conductivity of the materials studied.

Growth Temperature Uniformity of MBE-Grown GaAs Determined by Scanning Room Temperature Photoluminescence

1994 ◽  
Vol 340 ◽  
Author(s):  
K. Stair ◽  
T. Bird ◽  
A. Moretti ◽  
F. Chambers ◽  
C. Choi-Feng
Keyword(s):  
Growth Rate ◽  
Quantitative Analysis ◽  
Temperature Distribution ◽  
Quantum Well ◽  
Growth Temperature ◽  
Room Temperature ◽  
Epitaxial Layers ◽  
Temperature Uniformity ◽  
Room Temperature Photoluminescence

ABSTRACTWe have used scanning room temperature photoluminescence to map GaAs quantum well widthsand AIGaAs barrier compositions over 2-inch and 3-inch diameter epitaxial layers grown by MBE at temperatures ranging from 600 to 700ºC. Analysis of these maps allows a nondestructive quantitative analysis of the GaAs growth rate uniformity from which we can calculate the temperature distribution during growth. We have used this technique to compare the thermal uniformity of various substrate holders designed for use in the Intevac ModGenII MBE system.

Phosphorus Passivation of GaAs

1998 ◽  
Vol 510 ◽  
Author(s):  
S.P. Watkins ◽  
X. Xu ◽  
J. Hu ◽  
R. Ares ◽  
P. Yeo ◽  
...  
Keyword(s):  
Room Temperature ◽  
Thin Layers ◽  
Difference Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Room Temperature Photoluminescence ◽  
Reflectance Difference Spectroscopy ◽  
Similar Chemical ◽  
Pl Intensity ◽  
Undoped Gaas

AbstractWe have performed a systematic study of the effect of various phosphorus passivation techniques on the room temperature photoluminescence (PL) intensity of undoped GaAs. The effects of passivation by two methods are compared: (1) the P-exchange reaction on exposure to tertiarybutylphosphine (TBP) vapour between 500-620°C, and (2) the growth of thin layers of GaP directly on GaAs. An x-ray diffraction technique was used to estimate the thickness of the passivating layers. Reflectance difference spectroscopy indicated a similar chemical origin for the two passivation methods. Both passivation techniques resulted in strong enhancements in the room temperature PL. PL intensity was observed to increase very rapidly with adsorbed P for both cases saturating at approximately 2 monolayers equivalent GaP coverage.

Optical evaluation of pretreated InGaN quantum well structures

2003 ◽  
Vol 798 ◽  
Author(s):  
T. Böttcher ◽  
F. Bertram ◽  
P. Bergman ◽  
A. Ueta ◽  
J. Christen ◽  
...  
Keyword(s):  
Quantum Well ◽  
Quantum Wells ◽  
Room Temperature ◽  
Growth Direction ◽  
Wetting Layer ◽  
Quantum Well Structures ◽  
Room Temperature Photoluminescence ◽  
Decay Times ◽  
Wavelength Distribution ◽  
Ingan Quantum Wells

ABSTRACTIn order to optimize the quantum efficiency of InGaN quantum wells, different MOVPE growth sequences are compared using photo- and electroluminescence. In one study, the surface was pretreated with trimethylindium (TMIn) prior to the well deposition. In another study, growth interruptions were performed after the quantum well deposition to desorb segregated indium. In both cases, the room-temperature photoluminescence (PL) intensity is strongly enhanced. For the samples grown with TMIn preflow the wavelength distribution in low-temperature cathodoluminescence (CL) wavelength mappings is narrowed, which can be attributed to more homogeneous quantum wells. Furthermore, the decay times of the radiative recombination increase both at RT and 2K. A reason for this could be an improved indium profile along the growth direction or a more homogeneous In wetting layer due to the pre-wetted surface.

Above-room-temperature photoluminescence from a strain-compensated Ge/Si0.15Ge0.85 multiple-quantum-well structure

2012 ◽  
Vol 100 (14) ◽  
pp. 141905 ◽  
Author(s):  
P. H. Wu ◽  
D. Dumcenco ◽  
Y. S. Huang ◽  
H. P. Hsu ◽  
C. H. Lai ◽  
...  
Keyword(s):  
Quantum Well ◽  
Room Temperature ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Room Temperature Photoluminescence ◽  
Quantum Well Structure

scholarly journals Observation of Room Temperature Photoluminescence from Asymmetric CuGaO2/ZnO/ZnMgO Multiple Quantum Well Structures

2015 ◽  
Vol 15 (5) ◽  
pp. 3944-3950 ◽  
Author(s):  
P. M. Aneesh ◽  
M. K. Jayaraj ◽  
R. Reshmi ◽  
R. S. Ajimsha ◽  
L. M. Kukreja ◽  
...  
Keyword(s):  
Quantum Well ◽  
Room Temperature ◽  
Multiple Quantum Well ◽  
Multiple Quantum ◽  
Room Temperature Photoluminescence
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