Atomic force microscopy, micro-Raman scattering and Auger spectroscopy were applied to study stress and material composition in AlGa N grown by MOCHA on sapphire. Samples were annealed in N , O and air ambient between 800 °C and 1200 °C. Annealing at temperatures above 800 °C led to composition changes, cracks and defect formation resulting in stress release. Additionally, a change of built-in stress from tensile to compressive was observed after air annealing. Auger spectroscopy analysis showed this switching of stress to be related to oxygen incorporation. Oxygen accumulates in areas of macroscopic cracks as well as microscopic defects. Oxygen diffusion in AlGaN was found to be largely enhanced in the presence of water vapor in oxygen ambient. Samples were thermally stable up to 1100 °C in nitrogen and oxygen. Annealing in air led to a large surface oxidation.
|Number of pages||4|
|Journal||Physica Status Solidi (C)|
|Early online date||19 Dec 2002|
|Publication status||Published - Dec 2002|
|Event||2nd International Workshop on Nitride Semiconductors, IWN 2002 - Aachen, Germany|
Duration: 22 Jul 2002 → 25 Jul 2002