High quality GaN grown by MOVPE

Several nitrogen precursors have been used for the growth of GaN in MOVPE, but so far the best results were obtained using NH3, even though NH3 does not produce a significant amount of active species at the growing interface. To produce active species from N-2 or NH3, a remote plasma-enhanced chemical vapour deposition (RPECVD) process has been implemented. In addition, nitrogen metalorganic precursors, triethylamine and t-butylamine, were also used. To accurately control the critical parameters of the MOVPE of GaN, we have implemented a laser reflectometry equipment, which allows a real-time in situ monitoring of the different steps of the growth, i.e. nitridation of the substrate, nucleation, heat treatment, and deposition. Using an appropriate buffer layer, GaN grown on sapphire using NH3 as nitrogen precursor, shows sharp low temperature photoluminescence lines (4 meV at 9 K), whereas other nitrogen precursors did not lead to comparable electronic quality.