Grain Boundaries of Controlled Geometry in ZnO Films Grown by Chemical Vapor Deposition: Undoped and Bi -Doped Boundaries

We describe a chemical vapour deposition technique for the controlled growth of ZnO films, containing grain boundaries which are suitable for detailed atomic resolution studies. Using this technique, we have grown; (1) random polycrystalline, (2) highly textured polycrystalline and (3) nominally single crystal films Also, a technique for doping the grain boundaries in these specimens with Bi by an “in-diffusion” method is demonstrated. The grain boundary atomic level structure and chemistry is studied by means of High Resolution Electron Microscopy (HREM) and STEM/EDX microanalysis. Some results obtained from boundaries in textured polycrystalline films which have the c-axes in neighboring grains lined-up to ˜1 ° are described.