Microwave plasma assisted LCVD growth and characterization of GaN

Gallium nitride films have been grown by microwave plasma assisted laser induced chemical vapor deposition at about 550°C. Trimethylgallium and ammonia served as group III and group V sources, respectively. Ammonia was introduced into the reaction chamber by two separate lines. In one of the lines, ammonia first passed through a microwave cavity where it could be ionized into a plasma, before being delivered to the chamber. An ArF excimer laser (193 nm) was used to photodissociate the ammonia and trimethylgallium introduced through the other line. The room temperature electron concentration and Hall mobility of the films were measured to be in the range 10 ¹⁵-10 ¹⁶ cm ^-3 and up to 200 cm ²/Vs, respectively. Strong room temperature near-band photoluminescence detected from the films indicated their good optical quality. The photoconductive decay of photocarriers was also investigated.