Ab initio molecular orbital characterization of sources for photo-assisted radical beam epitaxy of group-III nitrides

Some insights into an experimental approach to the growth of defect-free epitaxial films of group-III nitrides were provided by an investigation based on ab initio molecular orbital methods. From the theoretical point of view, use of a molecular beam of dialkyl group-III nitrene characterized not only by two unpaired electrons almost localized at the nitrogen atom but also by the covalently bound pair of one group-III and one nitrogen atoms is advantageous to the low-temperature growth of stoichiometric group-III nitride. A previous result that the beam of dimethylaluminumnitrene ((CH3)2AlN) is obtainable by the method of photo-dissociation of energetic compound beams (PDECB) using dimethylaluminum azide ((CH3)2AlN3) as source material was confirmed by examinations of the decomposition mechanisms of dialkyl group-III azides. Furthermore, dimethylgallium azide ((CH3)2GaN3) possessing the nature of unimolecular metastable dye was found to be a promising PDECB source compound appropriate for photo-assisted chemical beam epitaxy of gallium nitride.