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High quality GaN layers on Si(111) substrates: AlN buffer layer optimisation and insertion of a SiN intermediate layer

We present a study on the material properties of GaN films grown on (111) silicon substrates by low-pressure metalorganic chemical vapour deposition using AlN buffer layers. This buffer layer is optimised with respect to growth temperature and time for the optical and structural properties of the GaN epilayers. The insertion of a Si x N y intermediate layer significantly increases the optical and structural properties. It results in a reduction of the D 0 X FWHM to 10 meV and in a 2.5-fold increase of its luminescence intensity. The FWHM of symmetric and asymmetric ω-scans are reduced from 832 to 669 arcsec and from 702 to 547 arcsec, respectively.