Characteristics of undoped and magnesium doped GaN films grown by laser induced MBE

Epitaxial GaN films were grown on sapphire (0001) and 6H–SiC (0001) by reactive laser ablation of a metallic Ga target under continuous nitrogen flow. As radiation source a Nd:YAG laser with 30 ps pulses and a pulse rate of 1–3 kHz was used. The undoped films revealed a Hall background carrier concentration of 6×10−17 cm−3 and an excitonic near band edge emission of 3.47 eV at 4.3 K. Mg incorporation into the Ga films was achieved by modulation of the evaporation from two targets (Ga and Mg) by laser beam scanning. CL, SIMS and AES measurements confirmed the Mg-doping of the films.