PLANAR INTERGROWTH STRUCTURES IN THE ZNO-IN2O3 SYSTEM

The accommodation of In2O3 in the ZnO wurtzite structure was investiga ted using a combination of atomistic simulation and HREM techniques. A t low concentrations, indium ions are incorporated on zinc sites with creation of zinc vacancies to maintain charge neutrality; defect clust ering involving two indium substitutional ions surrounding a zinc vaca ncy is energetically favourable. At higher concentrations, indium oxid e is accommodated by a series of intergrowth phases, consisting of ext ended planar defects stacked along the c-axis of the hexagonal wurtzit e structure. The proposed model for the In2O3-(ZnO)(m) phases consists of two indium oxide layers oriented along (0001) planes of ZnO separt ed by a ZnO wurtzite layer m/2 unit cells thick; each wurtzite region is displaced from the next by a translation of 1/3[01 (1) over bar 0]. The associated solution energies of these respective intergrowth phas es are similar in magnitude, and are much lower than solution energies for both isolated defects and defect clusters.