LASER-MICROWAVE PHOTOCONDUCTIVITY OF THERMALLY OXIDIZED SILICON-WAFERS - LASER WAVELENGTH AND POWER DEPENDENCE

Laser-microwave photoconductivity measurements were performed on therm ally oxidized silicon wafers. Using a 830 nm laser, an almost exponent ial decay profile and similar effective lifetime were observed for the range of laser powers (7.5-25 W) used while the decay profile using a 910 nm laser was found to be strongly dependent on the laser power us ed. The 910 nm laser gave an unusual decay profile which is attributed to the presence of emitting traps located interior to the wafer at de pths greater than 12 mu m from the surface.