High resolution x-ray diffraction characterization of semiconductor structures

Abstract

Abstract The high-resolution X-ray diffraction techniques, such as double-crystal rocking and triple-crystal diffraction, have become essential tools in the semiconductor materials and devices laboratory. Quick and non-destructive characterization is possible for basic layer parameters including layer composition, strain, mismatch and thickness. More sophisticated characterization of interface and quantum-well structures with submonolayer resolution is possible with the help of kinematical diffraction principles and diffraction profile simulation using the dynamical diffraction theory. These X-ray diffraction techniques are making it possible to correlate the structural properties to the epitaxial growth process, to the electrical,/optical properties and to the device performance. In this review article, I discuss some basic aspects of the instrument, simple determination of layer parameters, the dynamical and kinematical diffraction theories, and some recent results in the characterization of the heterostructure interfaces and strained quatum-well devices. I also discuss the diffuse scattering analysis of bulk semiconductors in the Bragg diffraction geometry. Interface analysis of the lattice-matched structures such as GaInAs/InP and AlGaAs/GaAs is discussed in terms of kinematical diffraction principles, namely the X-ray phase shift and the crystal truncation rod. Analysis of strained quantum wells is discussed using Bragg peak profile and Pendellosung fringe profile. Diffuse scattering in bulk semiconductors is discussed in the context of the analysis theory, namely the rocking-curve profile and the radial intensity profile around a reciprocal lattice point of the diffused scattered X-rays due to such defects as dislocation loops and spherical defect clusters.