Behaviour of the AlN cap during GaN implantation of rare earths and annealing

The structural evolution of 10 nm AlN caps grown on GaN layers has been investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) after growth, and implantation by rare earths ions and annealing at high temperature. The AlN cap relaxation is shown to take place by pinholes formation. During annealing at 1300 °C, pinhole-free areas of the AlN cap protect the GaN layer and allow efficient optical activation of the rare earths dopants. Through pinholes, an explosive dissociation of the GaN layer occurs. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)