X-RAY DIFFRACTOMETER WITHOUT MANUAL INTERVENTION FOR DETERMINING THICKNESS OF MULTIPLE NON-METALLICA CRYSTALLINE LAYERS, FOURIER-AND AVERAGE VALUE ZERO TRANSFORMATIONS

摘要

An x-ray diffractometry technique without manual intervention finds thickness of multiple layers of non-metallic crystalline material. A rocking curve is windowed to eliminate a main peak. The windowed curve is smoothed with a running average. The smoothed curve is subtracted from the windowed curve to yield a difference curve. The difference curve is transformed to make its average value zero and to constrain its endpoints to zero. A welch window is used. A fast Fourier transform is applied to the transformed difference curve. A thickness transform is applied to the result to yield a layer thickness. Examples: Ga As HEMT and silicon germanium thin film structures. General signal processing apparatus with the average value zero translation.