Coaxial rf-magnetron nitrogen activator for GaN MBE growth

Novel compact coaxial magnetron nitrogen activator with a radio frequency (rf) capacitively-coupled discharge has been used for the first time for GaN molecular beam epitaxial growth on different substrates, including GaAs(113). Optical emission spectra of the discharge have been studied as a function of nitrogen flow rate, rf power, and magnetic field, focusing on first negative (391 nm) and second positive (380 nm) lines associated with nitrogen molecular ions and excited molecules, respectively. Optimization of the activator parameters and distance of the discharge zone from the substrate resulted in GaN growth rate as high as 0.5 μm h−1 at a 350 l s−1 pumping speed.