Anomalously large band-bending for HF-treated p-Si surfaces

Electronic properties of the HF-treated Si surfaces have been characterized by the Kelvin method combined with surface photovoltage (SPV) measurements. With the use of 340 nm ultraviolet light source, a relatively large SPV of −0.45 V was detected at a photocurrent density of 1 mA/cm2 for the diluted (e.g. 4.5%) HF-treated p-Si(0 0 1) surface. On the other hand, no SPV was induced for the HF-treated n-Si(0 0 1) wafer. This result indicates that there is anomalously large surface band-bending toward the surface, and Fermi-level position at the surface is pinned in the vicinity of the bottom of the conduction band at the HF-treated p-Si(1 0 0). It is considered that the residual fluorine responsible for an anomalously large band-bending at the p-Si(1 0 0) surface treated with HF. Furthermore, the value of the built-in potential for the HF-treated p-Si(0 0 1) surface was estimated to be about 0.60 eV at the room temperature from the result of the temperature dependence of the effective saturation current.