抄録
We show several technique for improving the GaN-film quality in radio frequency plasma assisted molecular beam epitaxy (rf-MBE). The first technique is Silicon (Si)-doping to the buffer layer. The effect of the Si-doping modifies the growth mode at the initial stage and the surface morphology of the GaN films. Using the Si-doped GaN buffer layer, the electron mobility of the two-dimensional electron gas at AlGaN/GaN heterointerfaces is improved due to the decrease of the number of electron scattering centers. The second technique is the reduction of the growth rate in rf-MBE-GaN growth on MOCVD-grown GaN templates. This technique changes the growth mode from spiral mode to step-flow mode. These techniques improve the GaN-film quality by changing the surface morphology due to the nucleation of the GaN grains during the initial growth. Therefore, the growth control involving these techniques as well as the quality and orientation of buffer layers, templates and substrates influence the quality of the GaN films.
