Effect of Al doping in GaN films grown by metalorganic chemical vapor deposition

Abstract

The effect of Al doping in GaN films grown by metalorganic chemical vapor deposition was investigated using photoluminescence (PL), time-resolved PL, Hall measurements, and reciprocal space map. The electron mobility measured at 300 (150) K by a Hall measurement significantly increased from 170 (185) cm2/V s in the undoped sample to 524 (744) cm2/V s in the Al-doped sample grown with a molar flow rate ratio Al/(Al+Ga) of 0.056. When increasing the incorporation of Al in GaN, the band edge photoluminescence emission intensity was enhanced by about one order of magnitude compared to the undoped GaN. In addition, an increase in the decay lifetime of the GaN band edge emission was observed with the Al-doped GaN. In conclusion, the incorporation of only a small amount of Al in GaN was found to significantly reduce the point-defect-related electron scattering center associated with the compensating acceptors (Ga vacancies or their complexes) and nonradiative recombination centers, thereby improving the electrical and optical properties of GaN films.