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Evaluation of the crystal structure of a DVD recording layer

Using Rigaku's SmartLab multipurpose diffractometer to measure in-plane diffraction, the crystal structure, lattice constants and crystallite size of a polycrystalline thin film can be found. Nitrogen is added to a recoding layer (GeSbTe 20 nm) employed in various recording media, such as DVD, and the changes in crystallite size, lattice distortion and lattice constants are measured. The measurement results are shown below.

DVD recording


DVD recording


Amount of Nitrogen (at%) 0 1.5 3.0 4.5 6.0
Crystallite Size (Å) 278 348 242 195 154
TEM Observation 200 - 400   100 - 250    50 - 150
Lattice Distortion (%) 0.20 0.05 0.02 - -
Lattice Constant (Å) 6.034 6.049 6.055 6.059 6.060

As shown in the figure and table above, with this method, the change of crystallinity and its structure can be evaluated in detail using the actual media. The crystallite sizes agree well with the results determined by TEM observations.