Observation of Columnar Microstructure in Step-Graded [Formula presented] Films Using High-Resolution X-Ray Microdiffraction

Columnar microstructure in step-graded [Formula presented] structures with low threading dislocation densities has been determined using high angular resolution ([Formula presented]) x-ray microdiffraction. X-ray rocking curves of a [Formula presented]-thick strain-relaxed [Formula presented] film show many sharp peaks and can be simulated with a model having a set of Gaussians having narrow angular widths (0.013°–0.02°) and local ranges of tilt angles varying from 0.05° to 0.2°. These peaks correspond to individual tilted rectangular columnar micrograins having similar (001) lattice spacings and average areas of 0.8 to [Formula presented]. © 2002 The American Physical Society.