Atomically resolved carrier recombination at Si(111)-7×7 surfaces

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Abstract
The local potential created by photoexcited electron-hole pairs at the surface of clean and partially oxidized Si(111)-(7×7) surfaces is probed with a scanning tunneling microscope. Strong reductions in the surface photovoltage on the 15–20-Å length scale are observed due to localized surface recombination centers. The dependence of the local photovoltage on illumination intensity allows recombination effects to be distinguished from band bending. Virtually all defects on Si(111)-(7×7) increase the combination rate by destroying the two-dimensional order and increasing the coupling between surface and bulk states.