The goal of this work is to establish some design rules for dislocation filters in III-nitride based devices in order to improve their crystalline quality, i.e., their electrical performance. Linear elastic theory, thermodynamics and the reaction–kinetics approach [49] have been used to gain understanding and to develop models of the dislocation density in GaN based heterostructures.
This dissertation is divided into six chapters, including the current introductory chapter. Chapter 2 introduces the elements of linear elasticity theory useful to model dislocations. In Chapter 3 general elasticity theory is applied to evaluate the dislocation energy in hexagonal thin layers. In addition, dislocation energy is used to evaluate the equilibrium configuration of dislocations in III-nitrides. In Chapter 4, the previous results regarding the dislocation energy are used to extend the theoretical studies of the critical thickness for III-nitrides film. Subsequently (in Chapter 5) the reaction-kinetic approach is used to model the dislocation density in III-nitride bulk and multilayers with different geometries. Chapter 6 summarizes the work with the main achievements and presents an outlook for further studies.