Abstract
The number of N atoms in N-rich regions mostly due to nonrandom N incorporation in GaAsN (N∼4%), referred to as the Nr rate, is studied using a nonstandard Raman setup that addresses transverse symmetry. The Ga-N opticalrange shows a two-mode signal which discriminates between the N-poor ( Np ) and N-rich (Nr) regions. This is discussed via a percolation-based picture for Be-chalcogenide alloys, which exhibit mechanical contrast with regard to the shear modulus. This applies to GaAs-GaN even though the contrast is in the bulk modulus. The balance of Nr/Np strength provides a Nr rate of ∼30%, i.e., much larger than the corresponding Be rate of ∼4% in random Be-based alloys.