Dissertation - FTP Directory Listing - University of Surrey

And the absorption length L abs defined as the mean free path of a particle before undergoing a nonelasticinteraction in a given medium. = (2.3)As noted the absorption length and coefficient depend on wavelength and Figure 2.2 shows thedependence of absorption length and coefficient on wavelength for silicon.Figure 2.2 Wavelength dependence of absorption length and coefficient for silicon [11]In the visible region 0.4 - 0.6 µm the absorption length lies in the range 0.1 - 10 µm, setting somephysical constraints on the thickness of the substrate used for sensors.For effective light detection photo generated pairs must be separated from the thermal background.Three types of photo detectors designed to measure this signal are the photoconductor, thephotodiode and the photogate.5