Room temperature micro-photoluminescence measurements for monitoring defects in low-energy high-dose As and B implanted silicon

In this study we investigate the effect of dose rate on defect formation due to high-dose, low-energy arsenic and boron implantation into n-type and p-type Si (100) samples. Besides room temperature (RT) micro-photoluminescence imaging (μ-PL) various non-destructive characterization techniques are used to understand the structural changes before and after the heat treatment of the implanted wafers: photo-modulated reflectance (PMR), spectroscopic ellipsometry (SE), and surface photovoltage (SPV) measurements. As-implanted samples show enhanced defect formation with increasing dose rate. A more pronounced impact of dose rate has been found for boron implants indicating the different structural changes compared to the case of implanted arsenic ions. Annealing leads to the recrystallization of the implanted layer clearly indicated by the significant increase of the band-to-band PL photon yield. However, the presence of residual and re-organized defects can be observed manifesting in significant photoluminescence radiation in the sub-bandgap wavelength region. We show that monitoring of band-to-band and defect band PL provide valuable information on the implantation process even if the defect density is so high that single defect clusters and extended defects no longer can be identified as separated light emission centers. Our concept can be applied in high quality monitoring and process control of low-energy ion implantation and annealing processes.