The atomic and electronic structure of dislocations in Ga-based nitride semiconductors

The atomic and electronic properties of dislocations in III - N semiconductor layers, especially GaN, are presented. The atomic structure of the (a) over right arrow edge threading dislocation is now well established with three different cores ( 8 or full core, 5/ 7 or open core, and 4- atom ring). The use of atomistic simulations has confirmed these atomic structures and has given a good understanding of the electronic structure of the screw dislocation. Partial dislocations which are mostly confined in the area close to the substrate are now also being investigated. It is becoming clear that the electrical activity of all these defects is dependent on the layer quality, which is governed by the growth conditions.