On the non-linear dependence of photocarrier radiometry signals from Si wafers on the intensity of the laser beam
Centre for Advanced Diffusion-Wave Technologies (CADIFT), Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, M5S 3G8, Canada
2 Experimental Physics III, Rurh Universität Bochum, 44780 Bochum, Germany
The subject of this research was the dependence of the infrared photocarrier radiometric (PCR) signal on the intensity of the exciting super-bandgap laser beam. It has been shown that the amplitude of the PCR signal is proportional to the intensity to a power β, such that 1≤β≤2. The power dependence of the amplitude is an important indicator of the photoexcited carrier recombination physics, specifically in semiconductors ranging between monopolar (β = 1) and bipolar (β = 2) limits. The study was made with laser beams of varying power and spotsize and wafers with different transport parameters. It has been found that the conventional approach using β = 1 is inadequate and inconsistent with experimental slopes of amplitude vs. power.
© EDP Sciences, Springer-Verlag, 2008