Alloy broadening in photoluminescence spectra ofAlxGa1−xAs

Localization-enhanced biexciton binding in semiconductors

“…19 As localization energy E loc we take the photoluminescence width of the bound exciton. 33 E XX /E X changes from about 0.1 for GaAs to 0.4 for xϾ0. 15.…”

Comment on “Optical investigations of AlGaN on GaN epitaxial films” [Appl. Phys. Lett. 74, 2456 (1999)]

“…Thus, the values of calculated by Schubert et al 2 are more than a factor of 2 larger than those determined by several other groups. We suggest that the values of calculated by Zimmerman 6 and Lee and Bajaj 7 are more reliable as they do not use the ill-defined concept of an exciton volume.…”

“…They compare their experimental values with the results of a calculation by Schubert et al 2 and find, in general, a fair agreement; with the calculated values being somewhat larger, and therefore, suggest that their samples have negligible clustering. The purpose of this comment is to point out that before and after the work of Schubert et al, 2 several calculations 3-8 of the variation of with alloy composition were published with quite different results.…”

“…In addition, several experimental measurements of , especially in high-quality Al x Ga 1Ϫx As, 9 give values much smaller than those calculated in Ref. 2.…”

“…͑1͒ with V exc ϭ 4 3 a B 3 . Schubert et al 2 define V exc as V exc ϭ 4 3 a B 3 , and therefore, use 0 as a definition of excitonic linewidth, which is about 2.7 times larger than that determined by Goede, John, and Henning. 3 Singh and Bajaj 5 followed a quantum-mechanical variational approach and found equal to 0.32 0 .…”