Growth Mechanisms for CVD ZnO

For both AP-CVD and LP-CVD processes, deposition conditions have been found, which result in polycrystalline ZnO films that possess a strong preferential crystallographic orientation  

Boron-doped LP-CVD ZnO, as developed by Fay et al. [17] the corresponding XRD graph for an LP-CVD ZnO B layer is shown in Fig. 6.6. A strong preferentially oriented growth is observed here also, but it is, in this case, perpendicular to the (1120) crystallographic planes. This means that the c-axis is parallel to the substrate, in contrast with the orientation more commonly observed for AP-CVD and sputtered ZnO layers [15,25,26]. 

This means that these films are c-axis oriented. 

A closer view of the ZnO surface (see Fig. 6.7) reveals that the pyramids have nonregular facets, and are actually made up of a multitude of micro-steps. We can explain these steps as the successive stacking-up of (1120) and (0002) atomic planes, which are perpendicular to each other. Indeed, these planes possess the minimum surface energy density, which 

Variation in the Structural Properties with Film Thickness 

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