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Dependence of Interdiffusion in AlGaAs on Stoichiometry between Ga-RICH and As-Rich Solidus Limits
Published online by Cambridge University Press: 26 February 2011
Abstract
Al-Ga interdiffusion of undoped AlGaAs/GaAs multiple quantum wells was studied by varying the crystal defect concentrations and is shown to be mediated predominantly by column III vacancies from the Ga-rich to the As-rich side of the solidus. An increase of two orders of magnitude has been observed in the interdiffusion coefficient when going from the inclusion of excess Ga to excess As in the evacuated ampoule. The in-diffusion of column HI vacancies from the surface in an As-rich ambient, as well as the out-diffusion of column III vacancies from the n-type substrate in an As-poor ambient, were observed using secondary ion mass spectroscopy. The role of SiO2 and Si3N4 encapsulations in controlling the interdiffusion was also determined. We have also observed that the photoluminescence intensity in the Ga-rich crystal is several orders of magnitude stronger than that of the As-rich crystal. Finally, cathodoluminescence spectroscopy reveals a deep level which has been associated with a Ga vacancy complex in the samples annealed with excess As that correlates with the extent of Al-Ga intermixing.
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- Copyright © Materials Research Society 1992
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