Properties of GaN epitaxial layers grown at high growth rates by metalorganic chemical vapor deposition

GaN epitaxial layers were grown at high growth rates by increasing the inpu t trimethylgallium (TMG) flow rate while keeping the NH, flow rate constant in metalorganic chemical vapor deposition. The electrical and optical prop erties of the grown layers have been investigated. With the increasing TMG flow rate, the electron concentration tends to decrease gradually and the H all mobility decreases significantly. Considering the temperature dependenc e of the Hall mobility and the correlation between the Hall mobility and th e electron concentration, it has been indicated that the more accepters are incorporated and consequently the compensation ratio becomes higher with i ncreasing the TMG flow rate. Photoluminescence measurements have revealed t hat the intensity ratio of the bound exciton emission to the 2.2 eV band em ission, which is assumed to correlate to carbon or Ga vacancies, was decrea sed with increasing the TMG flow rate. It might be reasonable to take a lot of acceptor incorporation to explain the degradation of the electrical and optical properties in the samples grown at high growth rates by increasing the TMG flow rate.