Molecular beam epitaxy of GaN, AlN, InN and related alloys: from two- to three-dimensional growth mode

We demonstrate that the growth mode of GaN, AlN and InN in molecular beam e pitaxy is two or three dimensional, depending on the competing kinetics of the metal species (Ga, Al or In) and of N. In this view, we show that the p resence of foreign species acting as surfactants profoundly modifies the ki netics of the adatoms, eventually leading to an improvement in both structu ral and optical properties of the material. Next, we discuss the interplay between the growth mode and the strain relaxation in nitride heterostructur es. In particular, we show that GaN and InGaN can experience a Stranski-Kra stanov growth mode leading to the formation of quantum dots. A mechanism of quantum dot nucleation is proposed in the case of GaN on AIN. (C) 2000 Els evier Science S.A. All rights reserved.