CHARACTERIZATION OF GROUP-III NITRIDE SEMICONDUCTORS BY HIGH-RESOLUTION ELECTRON-MICROSCOPY

High-resolution electron microscopy has been used to characterize the microstructure of thin films of GaN, AIN and InN, as grown by plasma-enhanced molecular beam epitaxy. Zincblende and wurtzite polytypes were preferentially nucleated using (001) GaAs and (0001) 6H SiC substrates, respectively. Stacking faults and microtwins along {111} planes dominated the zincblende films, whereas stacking faults along {0002} planes and threading defects originating at the substrate surface were most prevalent in the wurtzite phase. Improved crystal quality was achieved by growing the films on suitable buffer layers.