Papers Published

1. Losurdo, M. and Capezzuto, P. and Bruno, G. and Namkoong, G. and Doolittle, W.A. and Brown, A.S., The chemistry of sapphire nitridation in relation to the GaN structural quality: Why low temperature 200°C nitridation?, Phys. Status Solidi A (Germany), vol. 188 no. 2 (2001), pp. 561 - 5 [1521-396X(200112)188:2<561::AID-PSSA561>3.0.CO;2-J] .
   (last updated on 2007/04/14)

   Abstract:
   The effect of c-plane sapphire nitridation upon exposure to an rf N₂ plasma at temperatures in the range 100-700°C on the quality of GaN epilayers grown by MBE is investigated. A homogeneous AlN layer is formed at 200°C. Nitridation at higher temperatures creates a rough and non-homogeneous nitridated layer including both AlN and NO. Lowering the nitridation temperature to 200°C results in the improvement of the GaN structural and photoluminescence properties. The results are interpreted in the framework of a chemical model based on the competition between formation of AlN and NO whose adsorption/desorption equilibrium on the sapphire surface strongly depends on temperature

   Keywords:
   annealing;chemisorption;gallium compounds;III-V semiconductors;nitridation;photoluminescence;sapphire;semiconductor epitaxial layers;semiconductor growth;substrates;thermally stimulated desorption;wide band gap semiconductors;