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Title: Native defects in the group III nitrides
Author: Kraeusel, Simon
ISNI:       0000 0004 2744 7734
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2013
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The promise of the broad range of direct band gaps of the (Al,Ga,In)N system is limited by the crystal quality of current material. As grown defect densities of InN, when compared with the more mature GaN, are extremely high and InN is strongly influenced by these defects. This is particularly important due to the unusual position of the charge neutrality level of InN, leading to both the well known surface charge accumulation and difficulties in p-type doping. While impurities and native defects clearly impact on the bulk carrier density in InN, the effects of threading dislocations on the electrical properties are still in dispute. Issues such as whether the dislocation line is charged or contains dangling bonds remain open. In this work an empirical Stillinger-Weber inter-atomic potential method is employed in a systematic global search for possible dislocation core reconstructions for screw and edge dislocations in GaN. The global optimisation of the dislocation cores is performed for a wide variety of core stoichiometries ranging from Ga rich to N rich. The most promising optimised core configurations are subsequently investigated using density functional theory for GaN and InN, in order to discuss relative stability under a wide range of growth conditions and their influence on the electronic properties of the bulk material.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available