Epitaxy of ternary nitrides on GaN single crystals

摘要

InGa_1-xN and Al-xGa_1-xN laeyrs were grown by metalorganic chemicla vapour depostion (MOCVD) on highly conductive signel crystals of GaN. The samples were ehn examined using X-ray diffractiona nd photoluminescence. It was found that there is a substantial difference in properties betweent he laerys grown on he N-face (00.{1}, chemically active, and Ga-face (00.1), chemically inert, sides. The latter layers had smaller free-electron concentration, better crysallographic quaity and different chemical compostion. All the examined layers were fully straiend, even for 1.1/100 lattic mismatch between the GaN substrate and about 0.1 μm thick In_0.11Ga_0.88N layer. The half-widths of the photoluminesce (PL) dominant peakds correspond to the compositonal gradient observed in X-ray diffraction. The positions of the PL peaks agree with the X-ray data if bowing paramers of 3.2 eV for InGaN lalyers and 0.25 eV for AlGan laeyrs were used.