Transmission electron microscopy of GaN layers grown by ELO and micro - ELO techniques

摘要

GaN layers grown on sapphire by micro-ELO (Epitaxial Lateral Overgrowth) technique are characterised by TEM (Transmission Electron Microscopy). The technique means that randomly distributed, amorphous SiN_x islands are deposited onto sapphire in a "Si/N treatment". Then a GaN nucleation layer (NL) is deposited at relatively low temperature, which is turned to high density of 3D GaN islands. During the overgrowth of such a nucleation layer by a thick GaN layer the dislocations are bent, because the amorphous SiN_x islands act like the regular pads of the classical ELO technique. Bending of dislocations and reduced dislocation density values (in the range of 10~7 cm~(-2)) are proved by TEM.