Early Stages of Pore Formation on Si During Etching in HF Solutions

The fabrication of porous silicon (PS) with controlled pore size distributions is of importance for reproducible manufacturing as well as it may help to elucidate the origin of light emission from this material. The pore formation on p‐doped Si(111) surfaces is studied. For this purpose hydrogen passivated surfaces are prepared by wet chemical treatment. After introduction into UHV system a 1 × 1 LEED pattern is readily obtained without any further treatment. These surfaces are etched at the open circuit potential (OCP) in HF solutions with pH‐values ranging from 1 to 10. Atomic force microscopy is used to characterize the dependence of pore formation on time and acidity. It is found that narrow pore size distributions can be obtained when HF solutions with high pH‐values are used.