A.P. Grzegorczyk

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.

Improvement of the Optical and Structural Properties of MOCVD Grown GaN on Sapphire by an in-situ SiN Treatment

In this paper, a study on the material properties of GaN films on sapphire substrates grown by low-pressure metalorganic vapor phase epitaxy using selective GaN islands as buffer layer is presented. The optical quality of the GaN layer grown with the optimized island buffer layer is significantly increased compared to the standard two-step method, i.e. a reduction of the D 0 X FWHM to 4 meV and an increase of the luminescence intensity. A blue shift of the excitonic transitions revealed an increase in residual stress. Rocking curve measurements and photo-enhanced etch experiments (PEC) demonstrated that the dislocation density decreases from 6 x 10 9 to 8 × 10 8 cm -2 .