Strain cancellation by indium incorporation for the calibration of nitrogen fractions in GaAsN

Abstract

This paper reports a study of strain cancellation by adding indium to GaAs1−yNy epitaxial layers as a method of calibrating the nitrogen fraction y. The aim was to determine the In fraction x in an InxGa1−xAs1−yNy epitaxial layer which exactly cancels the strain present in a GaAs1−yNy layer with the same nitrogen content when grown on a GaAs substrate. This is an alternative to asserting nitrogen fractions in GaAs1−yNy layers on the basis of x-ray measurements, when the values and linearity of lattice and elastic constants with nitrogen composition y has not been established. The GaAs1−yNy and InxGa1−xAs1−yNy layers were grown on GaAs (001) substrates using molecular beam epitaxy with an electron cyclotron resonance nitrogen plasma source. Layers have been assessed by high-resolution x-ray diffraction to determine the relationship between the lattice constant of the GaAs1−yNy layer and the fraction x of In required to exactly cancel the strain.