NITROGEN EFFUSION AND SELF-DIFFUSION IN (GAN)-N-14 (GAN)-N-15 ISOTOPEHETEROSTRUCTURES/

(GaN)-N-14/(GaN)-N-15/(GaN)-N-14 isotope heterostructures are used to study nitrogen self-diffusion by secondary-ion mass spectrometry and t hermally activated decomposition. After interdiffusion of (GaN)-N-14 a nd (GaN)-N-15 layers at temperatures between 770 degrees C and 970 deg rees C the diffusion profiles are measured. The isotope heterostructur es are particularly well suited for self-diffusion studies because the diffusion takes place at the interface inside the GaN crystal, and th erefore the analysis is free from perturbations such as surface electr ic fields, mechanical stress or chemical potential gradients. The temp erature dependence of the nitrogen self-diffusion coefficient (D) in h exagonal GaN was determined to be 1600 cm(-2) s(-1) exp [(-4.1. +/- 0. 4) eV/k(B)T], leading to a self-diffusion entropy S-SD of about 10k(B) . The nitrogen Bur through an isotope interface is compared with the n itrogen loss from a free GaN surface in vacuum above the decomposition temperature, to obtain information about the diffusion kinetics relev ant for epitaxial growth and high temperature device applications.