Density Functional Theory Study Of Surface Reactions On InN

InN and its alloys have recently received considerable interest because of theirpotential applications in optoelectronic and microelectronic devices. As the science andtechnology of InN advances, questions involving surface chemistry are becoming moreimportant. Especially, material growth, surface processing and chemical reactivity aredependent on the reaction mechanism of surfaces. So the systematical theoreticalinvestigations at an atomic level on the surface structure and adsorption of InN surfacesare necessary.In this paper, we first summarize the study background of this field, then, employingthe density functional theory together with the periodic slab models, the perfect anddefective InN surfaces, small inorganic molecules and atom adsorption on these surfacesare systemically studied. Our results are as follows.1. By studying the structures and electronic properties of the perfect and defectiveInN (0001) and (000-1) surfaces, it is clear that, the p orbital of the outmost In atomsproduces a dispersive surface state and the surface exhibit metallic character. Theformation of defects on (0001) surface weakens the original p surface states. The defectson semiconductor (000-1) surface introduce defect levels inside the original band gap,thus the original gap disappears or is reduced.2. The adsorption behavior and reaction processes of O2, N2O on InN surfaces arestudied. Our results reveal that these small molecules adsorbed on the surfaces with highexothermicity. There is a great barrier for the dissociative adsorption of O2on (0001)surface. While on (000-1) surface, O2can be easily dissociated and the dissociated Oatoms formed an oxidization layer with In2O3structure, passivating the (0001) surface.N2O is decomposed into N2and adsorbed O of In2O3bonding configuration. The barrierof the process is only45.0KJ/mol, which shows that N2O is expected to be a goodoxidation agent that can passivate the InN surface at room temperature. By calculating theelectronic structure of dissociated systems, our results reveal that the surface states are allweakened after dissociated O adsorption.3. We carry out a theoretical study of O atoms adsorption and incorporation at the InN (0001) and (000-1) surfaces. It is found that O atoms preferentially adsorb at H3siteof InN (0001) surface. For (000-1) surface, O atoms preferentially adsorb at H3or T4site.The O atoms preferentially incorporate at the surface region. By calculating the electronicstructure of O doped system, our results reveal that the fermi level of InN (0001) surfaceis raised and a new gap appeares after O doped.