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



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 SiNx 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 SiNx islands act like the regular pads of the classical ELO technique. Bending of dislocations and reduced dislocation density values (in the range of 107 cm–2) are proved by TEM. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)