Comparison of the interfacial relaxation between AlN/Al_2O_3 (0001) and AlN/6H-SiC (0001) studied with TEM

摘要

We investigate the interfacial relaxation of AlN on Al_2O_3 and on 6H-SiC by TEM.We find a typical dislocation density of 10~9cm~-2 in a subsequently grown GaN layer for both substrates despite a clearly different lattice mismatch.HRTEM images of the AlN/Al_2O_3 interface reveal confined misfit dislocations which relax the mismatch efficiently to a residual strain #epsilon#_r approx approx -0.7