Diffusion of In atoms in InGaN ultra-thin films during post-growth thermal annealing by high-resolution Rutherford backscattering spectrometry

Diffusion of In atoms was observed in InGaN ultra-thin films (3 nm thickness), which were prepared by radio-frequency induced nitrogen plasma source MBE (RF-MBE) and subsequent thermal annealing, using high-resolution Rutherford backscattering spectrometry (HRBS). To suppress decomposition of In atoms, cap-GaN layer was grown onto InGaN film. In-related signal clearly appeared in the HRBS spectra after post-growth thermal annealing at 875 C for 10 min. The thickness of InGaN layer with post-growth thermal annealing increased comparing with that before annealing; On the contrary, the thickness of the cap-GaN layer decreased. This result indicates that diffusion of In atoms occurred at GaN/InGaN interface. The diffusion coefficient is estimated to be approximately 3.8 x 10-18 cm2/s. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)