Determination of the surface recombination velocity of unpassivated silicon from spectral photoconductance measurements

Bare, non-diffused silicon wafers of different resistivities and surface conditions have been analyzed with a spectral photoconductance technique. The surface recombination velocity has been calculated by fitting the measurements with a theoretical model. The main result is that the surface recombination velocity is not constant, but decreases with increased resistivity, both for n-type and p-type wafers. The surface recombination velocity was found to vary from /spl sim/10 cm/s for 1000 /spl Omega/cm Si to /spl sim/10/sup 5/ cm/s for 0.3 /spl Omega/cm Si. These values are much lower than the previously assumed 'infinite' surface recombination velocity of 10/sup 6/-10/sup 7/ cm/s for bare silicon.