FORMATION OF GaN NANOCRYSTALS IN SiO2/Si

Abstract

Ga and N ions were implanted into a silicon dioxide layer on crystalline silicon. Ion energies were adjusted for obtaining an overlap of the depth profiles at a depth close to the surface. The chosen ion fluences result in maximum concentrations of about 9at.%. Rapid thermal annealing with halogen lamps was performed in nitrogen/ammonia ambient. Optimum annealing conditions for retaining the implanted species within the samples were found to be 1000°C and times between 30 and 120 s. Formation of Ga-N bonds was demonstrated by extended X-ray absorption fine structure measurements. Best results were obtained after annealing at 1000°C for 90 s. In this case pictures of cross section transmission electron microscopy show dark areas which are related to the higher mass of Ga atoms. High-resolution pictures reveal the existence of nanocrystals.