PLASMA CHARACTERISTICS AND THE GROWTH OF GROUP III-NITRIDES BY METALORGANIC MOLECULAR-BEAM EPITAXY

Improved quality and controllability of growth processes are key issue s for the maturation of III-N technologies. One of the most important concerns for the growth of III-N materials in ultra high vacuum is the ability to provide an effective nitrogen flux to the growth surface. This work has sought to correlate radio frequency (rf) plasma paramete rs and their impact on the growth of GaN by plasma-assisted metalorgan ic molecular beam epitaxy. Utilizing optical emission spectrometry, th e atomic nitrogen production has been optimized as a function of rf po wer and N-2 flow rate. Growth experiments indicate that the abundance of atomic nitrogen alone does not control growth. Increasing energy pe r molecule in the rf source, with a constant level of atomic nitrogen, dramatically decreases the GaN growth rate. High levels of atomic nit rogen with a low energy per molecule resulted in restoration of the gr owth rate to similar to 0.5 mu m/h.