xrd (x-ray diffraction)

XRD (X-Ray Diffraction) analyzes crystal structure, orientation, strain, composition, and film quality by measuring how X-rays diffract from atomic planes. **Bragg's Law**: n*lambda = 2*d*sin(theta). Diffraction peaks occur at angles where path difference between reflections from successive atomic planes equals integer wavelengths. **Applications in semiconductor**: Crystal quality assessment, film composition (SiGe Ge fraction), strain measurement, epitaxial layer characterization, phase identification. **High-resolution XRD (HRXRD)**: Precisely measures lattice parameter differences. Detects strain and composition in epitaxial layers with ppm-level lattice mismatch sensitivity. **Rocking curve**: Scan angle around Bragg peak. Peak width indicates crystal quality - narrow = high quality, broad = defective or strained. **Reciprocal space mapping (RSM)**: 2D scan of diffraction space. Separates strain from composition effects. Distinguishes relaxed from strained layers. **Film stress**: Lattice parameter changes with stress. XRD measures d-spacing changes to calculate stress in crystalline films. **Texture analysis**: Measures preferred crystal orientation (texture) in polycrystalline films. Important for metal grain structure and barrier properties. **Thin film analysis**: Grazing incidence XRD for surface-sensitive measurement of thin films. **Equipment**: Cu K-alpha source (0.154nm) with high-resolution optics (monochromator, analyzer crystal). **Vendors**: Bruker, Malvern Panalytical, Rigaku.