Photoluminescence Excitation Spectroscopy of Diffused Layers on Crystalline Silicon Wafers

Photoluminescence (PL) excitation spectroscopy is applied to observe the evolution of the luminescence spectra from dopant-diffused crystalline silicon wafers with varying excitation wavelength. Utilizing the micrometer-scale spatial resolution achievable with confocal optics in a micro-photoluminescence spectroscopy system, along with the well-resolved luminescence peaks at cryogenic temperatures from various defects and structures in a single-silicon substrate, we are able to examine the doping densities and junction depths of various boron-diffused wafers, as well as the distribution of defects induced underneath the wafer surface by the post-diffusion thermal treatment. Our conclusions are validated by photoluminescence scans and transmission electron microscopy applied to vertical cross sections, which confirm the presence of dislocations below the diffused regions.