Determination of indium composition fluctuations in InGaN/GaN quantum wells by quantitative high-resolution electron microscopy

InGaN/GaN single quantum well (QW) structures with a nominal In concentration of 16 % were grown on Al₂0₃(0001) substrates by MOCVD. The real In concentration in a series of samples with nominal QW thicknesses between 0.8 nm and 6.6 nm – grown under identical conditions – was determined by high-resolution TEM on a nanometer scale with the DALI (Digital Analysis of Lattice Images) evaluation program.