Effects of HF cleaning and subsequent heating on the electrical properties of silicon (100) surfaces

Abstract

Changes in surface-band bending of both boron-doped and phosphorus-doped silicon (100) samples by exposure (40 s) to hydrofluoric acid (HF) with varying HF concentrations were studied by x-ray photoelectron spectroscopy. Effects of subsequent thermal annealing was investigated by in situ heating in vacuum. Hydrogen termination of the dangling bonds on silicon was found to be an effective means to reduce surface gap states on silicon. Near-flatband surfaces were observed on both n- and p-Si by the HF exposure when the doping concentration was not less than 1×1016/cm3, and when the HF concentration was not higher than 5%. A higher HF concentration promoted hydrogen diffusion and the formation of an H-B species in p-Si. As such, band bending increased on p-Si. However, the deactivation of boron could be recovered by annealing for less than 1 h at a temperature as low a 120 °C.

Integrated freestanding single-crystal silicon nanowires: conductivity and surface treatment

“…The inversion of carriers has been observed in HF treated ultrathin silicon membranes [26] and is also a result of bulk studies [26][27][28][29][30]. The inversion of electronic conduction from p-type to n-type depending on the surface condition of the SiNW can be described by Fermi energy pinning [31,32] as we will discuss later.…”

Change in band alignment of HfO2 films with annealing treatments

“…The reported and calculated Fermi energy state of p-Si with a resistivity of 2 -5 ⍀ cm was 98.90 eV± 0.1, which is 0.35 eV less than the Fermi energy of intrinsic Si at 99.25 eV. 8,9 The Si 2p binding energy of the as-grown HfO 2 on Si was measured at 99.2 eV, as shown in Fig. 1, indicating that band bending occurred near the HfO 2 / Si interface of our samples.…”

Geometric and chemical components of the giant piezoresistance in silicon nanowires

“…2(a)), have switched type and become more resistive by up to 5 orders of magnitude? A possible explanation is the neutralization of the Boron acceptors by atomic hydrogen which can occur within a few micrometers of the surface [23,24], sufficient in the case of SiNWs to neutralize all acceptors. Natural re-oxidation of an HF treated surface is also known to create an interface defects that are principally donor-like [25], possibly accounting for the weakly n-type nature of the SiNWs.…”