Abstract :
GaN dots were deposited on AlN underlayers by alternate supply of trimethylgallium (TMG) and ammonia (NH3) in an
inductively heated quartz reactor operated at atmospheric pressure. Various growth parameters including deposition temperature,
TMG admittance and pulse time between TMG and NH3 exposures were proposed to investigate the influence of growth
parameters on the size distribution of GaN dots. It appears that GaN dots with uniform size distribution can be achieved under
certain growth conditions. Based on the study of atomic force microscopy (AFM), high deposition temperature was found to be
in favor of forming large GaN dots with small dot density. Decrement of TMG flow rate or reduction in the number of growth
cycle tends to enable the formation of GaN dots with small dot sizes. The results of room temperature (RT) cathodoluminescence
(CL) measurements of the GaN dots exhibit an emission peak at 3.735 eV. A remarkable blue shift of GaN dot emission was
observed by reduced temperature photoluminescence (PL) measurements
