Surface morphology and carbon incorporation for hexagonal GaN/(111)B GaAs metalorganic vapor phase epitaxy using dimethylhydrazine and trimethylgallium

Using dimethylhydrazine (DMHy) as a group V source, we grew hexagonal GaN layers on (111)B GaAs substrates by low-pressure metalorganic vapor phase epitaxy. The surface morphology of the hexagonal GaN layers and the carbon incorporation in them strongly depend on the V/III ratio and the reactor pressure, A flat GaN surface can be obtained at the V/III ratio oi 60 and the substrate temperature of 850 degrees C. The carbon concentration decreases with increasing reactor pressure and the minimum concentration is 2 x 10(19) cm(-3) for hexagonal GaN grown at 300 Torr. Low-temperature photoluminescence measurements reveal that the band edge emission for the GaN grown at 300 Torr is dominant compared with that of a deep level.