Properties of GaN Epitaxial Layers Grown at High Growth Rates by Metalorganic Chemical Vapor Deposition

摘要

GaN epitaxial layers were grown at high growth rates by increasing the input trimethylgallium (TMG) flow rate while keeping the NH3 flow rate constant in metalorganic chemical vapor deposition. The electrical and optical properties of the grown layers have been investigated. With the increasing TMG flow rate, the electron concentration tends to decrease gradually and the Hall mobility de- creases significantly. Considering the temperature dependence of the Hall mobility and the correlation between the Hall mobility and the electron concen- tration, it has been indicated that the more acceptors are incorporated and consequently the compensation ratio becomes higher with increasing the TMG flow rate. Photoluminescence measurements have revealed that the intensity ratio of the bound exciton emission to the 2.2 e V band emission, which is assumed to correlate to carbofiorGa vacancies, was decreased 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.