GaN epilayers were grown by metal-organic vapor phase epitaxy (MOVPE) on
z- and x-cut lithium niobate substrates. Ex-situ characterizations of the
epilayers by means of scanning electron microscope, atomic force microscope,
X-ray diffraction and micro-Raman scattering measurements have revealed same
growth features on both substrates. The observation of the morphology shows
homogeneous and relatively smooth surface. The shape and density of GaN
islands as well as the observed columnar growth mode are not dependent of
the orientation of the LN substrates. The X-ray diffraction analysis of 450 nm thick GaN layers grown at 730 °C on z- and x-cuts showed that both GaN
layers reveal the same crystallographic orientation, i.e. c-axis
orientation normal to the substrate plane and in-plane orientation that
coincides with the primary axis of LN substrates. The Raman scattering
measurements confirm the growth of an oriented epitaxial GaN layer on LN
substrate. Moreover, the deposited layer exhibit a quite good homogeneity,
since the Raman spectra recorded for different positions in the layer do not
reveal any significant variations in their relative intensities and
frequency shifts.