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Author Pradhan, A. ♦ Mukherjee, S. ♦ Satpati, B. ♦ Bhunia, S. ♦ Maitra, T. ♦ Nayak, A.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword NANOSCIENCE AND NANOTECHNOLOGY ♦ ALUMINIUM ARSENIDES ♦ ANNEALING ♦ BRAGG CURVE ♦ CONCENTRATION RATIO ♦ DEPLETION LAYER ♦ DIFFUSION BARRIERS ♦ GALLIUM ARSENIDES ♦ OPTOELECTRONIC DEVICES ♦ PHASE STABILITY ♦ QUANTUM WELLS ♦ REFLECTIVITY ♦ SUBSTRATES ♦ SUPERLATTICES ♦ TRANSMISSION ELECTRON MICROSCOPY ♦ VAPOR PHASE EPITAXY ♦ X-RAY DIFFRACTION
Abstract Atomic Cu-Pt type ordering in monolayer scale is well known in Ga{sub 0.5} In{sub 0.5} P epitaxial layers leading to change in its bandgap. Despite wide scale use of Al{sub x}Ga{sub 1-x}As (0<x<0.7) in various optoelectronic devices and quantum well structures, spontaneous ordering in this system was not well studied beyond monolayer scale. In this work, we report observation of natural superlattice ordering due to compositional variation in MOVPE grown Al{sub x}Ga{sub 1-x}As epitaxial layers. Clear evidence of such ordering was first noticed in the barrier layers of GaAs/Al{sub 0.3}Ga{sub 0.7}As quantum well structures. Further investigation on bulk epitaxial growth of Al{sub x}Ga{sub 1-x}As layer with different composition (x=0.2) has also confirmed existence of such structures. We have probed the sample using high resolution Transmission Electron Microscopy coupled with x-ray rocking curve (XRC) and reflectivity (XRR) measurements. Sharp superlattice peaks around (004) substrate Bragg peak as well as around (002) forbidden peak in XRC have been observed. Similar peaks are present in XRR also. We have presented detailed analysis of X-ray diffraction data with the help of kinematical diffraction theory here. The stability of the superlattice structures has been further investigated by annealing the sample at different temperatures.
ISSN 0094243X
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-05-06
Publisher Place United States
Volume Number 1728
Issue Number 1


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