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

This paper reports a study of strain cancellation by adding indium to GaAs
_1-y
N
_y
epitaxial layers as a method of calibrating the nitrogen fraction y. The aim was to determine the In fraction x in an In
_x
Ga
_1-x
As
_1-y
N
_y
epitaxial layer which exactly cancels the strain present in a GaAs
_1-y
N
_y
layer with the same nitrogen content when grown on a GaAs substrate. This is an alternative to asserting nitrogen fractions in GaAs
_1-y
N
_y
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 GaAs
_1-y
N
_y
and In
_x
Ga
_1-x
As
_1-y
N
_y
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 GaAs
_1-y
N
_y
layer and the fraction x of In required to exactly cancel the strain.