Time-resolved cavity ringdown spectroscopy on nanoparticle generation in a SiH4–H2 VHF plasma

Time-resolved cavity ringdown (t-CRD) spectroscopy has been applied to monitor the silyl (SiH3) radicals and nanoparticles in a pulsed very high frequency (VHF) silane-hydrogen plasma under microcryst. silicon (micro c-Si:H) deposition conditions. The measured cavity loss reveals four time intervals (I up to VI) in the first 4 s of the plasma pulse. By variation of the laser wavelength, it is demonstrated that the small cavity loss at 220 nm reflects the SiH3 absorption in interval I. In intervals II and III, an addnl. cavity loss appears. This addnl. cavity loss corresponds to Rayleigh and Mie scattering by growing nanoparticles. Interval IV reflects the loss of nanoparticles between the electrodes during the afterglow of the plasma pulse. The evolution of the nanoparticle generation detd. from the t-CRD measurements are further confirmed by addnl. SEM analyses on the nanoparticles created in the plasma pulse. [on SciFinder (R)]