Comparison of strain relaxation in InGaAsN and InGaAs thin films

Abstract

We compare the strain relaxation of In0.08Ga0.92As and In0.12Ga0.88As0.99N0.01 epitaxial thin films grown on GaAs (001) by elemental-source molecular-beam epitaxy. The epilayers we studied were essentially identical in their compressive lattice mismatch (0.62±0.02%), and thickness (600 nm). The strain state of the samples was determined by in situ substrate curvature monitoring, and by ex situ x-ray diffraction and plan-view transmission electron microscopy. We observe a slower rate of strain relaxation, and a 25% higher residual strain in the nitride. This is attributed to the presence of nitrogen interstitials in the InGaAsN epilayers and/or to the higher nitrogen bond strengths. © 2002 American Institute of Physics.