Low temperature growth of GaN single crystal films using electron cyclotron resonance plasma excited metalorganic vapor phase epitaxy

Abstract

A novel low-temperature-growth technique for GaN single crystal films has been developed utilizing electron cyclotron resonance (ECR) plasma excitation. The GaN film is grown in a low pressure metalorganic vapor phase epitaxy (MOVPE) system employing the reaction of trimethylgallium (TMG) with highly activated nitrogen produced by ECR excitation of ammonia. Using this ECR excitation technique, GaN single crystal films are grown on a sapphire basal plane at low substrate temperatures from 300 to 400° C under a molar ratio of NH 3 to TMG of 100 and a growth pressure of 2 × 10 −4 Torr. Furthermore, Zn-doped GaN single crystal films are successfully grown by adding dimethylzinc. The surface morphology of the GaN film is very smooth and the electrical properties of the undoped film are comparable to those with a MOVPE technique at high growth temperatures. Photoluminescence experiments at room temperature reveal that a blue luminescence peak appears in Zn-doped GaN and that the peak shifts to longer wavelengths with increases in the Zn-doping level.