Structural properties of group III nitrides grown on SrTiO3 (111) substrates by pulsed laser deposition

We have grown group III nitrides on SrTiO3 (STO) substrates using pulsed laser deposition (PLD) and investigated their structural properties by high resolution X-ray diffraction (HRXRD) and reflection high energy electron diffraction (RHEED). We have found that AlN and GaN grow epitaxially on STO (111) substrates. The epitaxial relationship between the nitrides and SrTiO3 substrates is nitrides(0001) \\ SrTiO3(111) and nitrides[10-10] \\ SrTiO3[11-2]. The in-plane alignment is rotated by 30 along the c-axis from that expected by the notion of lattice matching. It has also been found that AlN grown on SrTiO3 is dilated by 0.4% in the [0001] direction due to the lattice mismatch and the smaller thermal contraction rate.