In Situ Photoluminescence Analysis of Nonradiative Recombination on Silicon Surfaces Treated in Fluoride Solution

Recombination at p-type Si(100) surfaces electrochemically treated in NH4F solution is investigated in situ by photoluminescence (PL) under excitation with short pulses of a N2-laser. By registration of the integrated PL intensity we detect sensitively changes in the surface defect concentration. Periodic variations of the nonradiative recombination rate during electropolishing in the oscillating regime together with surface passivation by hydrogenation are observed. The estimated density of the surface nonradiative centers changes from 1013 cm-2 during the electropolishing to 5×1010 cm-2 for quiescent hydrogenated surfaces.