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Probing the AlxGa1-xN Atomic Distribution via UV-Photoluminescence and Raman at Sub-νm Scale
Published online by Cambridge University Press: 01 February 2011
Abstract
The spatial dependence of the band-gap light-emission energy of AlxGa1-xN alloys at composition 0≤ × ≤1 was studied via deep UV-photoluminescence (PL) and Raman microscopy. The data were acquired in a random fashion from an area of ∼ 1mm2 on the sample at steps of ∼1 νm - 200 νm utilizing the 244 nm laser line of probing spot size ∼300 nm radius. Our study indicates that the PL emission energy exhibits random type variations depending on locality: the alloys of composition x=0.12, x=0.22, and x=0.70 exhibit variations of ∼ 10 meV, 30 meV, and 25 meV respectively. The PL of the pure GaN exhibits no spatial dependence while the alloy of x=0.50 exhibits a variation around ∼ 45 meV. Moreover, the functional dependence of the band-gap Eg, on the composition was found to be Eg(x)=3.4(1-x)+6.2x-1.2x(1-x) from which the compositional variation, δx, can be computed for a given variation in the PL emission energy after accounting for the stress effect in the alloys.
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- Copyright © Materials Research Society 2002