EPITAXIAL-GROWTH OF GAN ON SI (100) SAPPHIRE (0001) USING RF PLASMA-ASSISTED IONIZED SOURCE BEAM EPITAXY

A new approach to epitaxial GaN growth utilizing radiofrequency plasma-assisted ionized source beam epitaxy (PAISBE) is described. To facilitate the reaction between Ga and atomic nitrogen, the Ga beam was partially ionized and accelerated. The reactive atomic nitrogen flux was obtained from an RF discharge nitrogen plasma with controllable power and frequency. A grid was placed at the exit of the plasma tube to prevent N2- from hitting the substrate. The growth parameters were chosen to systematically investigate the effects of Ga-beam ionization and grid bias. The crystal quality of the PAISBE-grown GaN was analysed by RHEED and x-ray diffraction. The FWHM of a 0.4-mum-thick GaN epilayer grown with ionized Ga beam and RF nitrogen plasma with 140 W power was measured to be 25 min at (0002) diffraction peak. This and other preliminary data from the present study indicate that PAISBE is a promising technique for GaN growth.