Epitaxial aluminum nitride thin films on 6H-silicon carbide, grown by magnetron sputter deposition

Abstract: The research presented in this thesis is focused on epitaxial wurtzite-structure Aluminum Nitride (AlN) thin film synthesis, by ultra-high-vacuum (UHV) de magnetron sputter deposition, on Silicon Carbide (6H-SiC) substrates. The emphasis of the work has been put on controlling the growth and quality of the films to be able to use this material in electronic device applications.The quality of epitaxial AlN films is significantly improved by using low­ energy ion assistance (Ei = 17-27 eV), during growth. The ion-assisted growth results in an increased surface mobility, which promotes domain boundary annihilation and epitaxial growth. This results in lateral expansion of column width (100 nm-wide at film thickness above 100 nm). The film characterization results show a very good crystal quality as well as high purity material. The measured concentrations of O, C, and Si in the film are at 3.5x1018, l. 3x1018 and 3.5xl 018 cm-3, respectively, which are among the purest AlN material as has been reported. The appearance of near band­ edge CL emission (6.02 eV at 4K) is also an evidence ofa high quality material.