Phase-controlled metal-organic chemical vapor deposition epitaxial growth of GaN on GaAs(100) using NH3

Cubic and hexagonal GaN epitaxial films were grown on GaAs(100) substrates by low pressure metallorganic chemical vapor deposition using NH3 as a nitrogen source. Analysis of X-ray diffraction spectra and transmission electron microscopy measurements show a transformation from (0002) hexagonal or (111) cubic phase to (200) cubic phase GaN as the growth temperature is raised from 530 to 600 °C. The hexagonal phase is found to dominate as the temperature is further increased above 650 °C while the cubic phase dominated in the range of 570–650 °C. Selected-area electron diffraction and electron micro-diffraction tests confirm the results. The full width at half-maximum of the (200) diffraction peak from cubic GaN grown at 600 °C was about 1°, independent of V/III ratio (3000–7500) and for thickness up to 1 μm.