The effects of the time-dependent and exposure time to air on Au/epilayer n-Si Schottky diodes

A study on Au/n-Si Schottky barrier diodes (SBDs) parameters with and without thin native oxide layer fabricated on n-type Si grown by LPE (Liquid-Phase Epitaxy) technique has been made. The native oxide layer with different thicknesses on chemically cleaned Si surface was obtained by exposing the Si surfaces to clean room air before metal evaporation. The native oxide thicknesses of samples D2, D3, D4 and D5 are in the form D2 < D3 < D4 ≤ D5 depending on the exposing time. It has been seen that the value of the barrier height Φb of samples D2 (0.64 eV), D3 (0.66 eV), D4 (0.69 eV) and D5 (0.69 eV) increases with increasing the exposure time and tends to that of the initial sample D1 (the initial sample, 0.74 eV), and thus also their I − V curves. Especially, the experimental results related to the exposure time of the surfaces to clean air are close in agreement with recently results reported for the HF-treated n-Si surface during initial oxidation in air. Furthermore, it has been determined experimentally that ageing of the Au contacts on the oxidized epilayer Si leads to barrier height values close to those measured for Au on chemically cleaned surfaces.