Influence of Minority Carrier Gas Donors on Low-Frequency Noise in Silicon Nanowires

The interaction of gases such as NH₃ and NO₂ with the surface of core/shell Si/SiO₂ nanowires has been shown to influence their electrical conductivity because NH₃ and NO2 are electron and hole donors, respectively. Using arrays of n- and p-type Si nanowires, we demonstrate that their influence on the low-frequency noise characteristics of the nanowires is largest when the donors are minority carriers. The impact of NO₂ and NH₃ on 1/f noise of p- and n-type nanowires, respectively, is limited. However, 1/f noise increases in n-Si nanowires under influence of NO₂ while it decreases in p-Si nanowires for NH₃. This effect is attributed to oxygen vacancies in the SiO₂ and the presence or absence of holes, h⁺ in the humid gas environment. In addition, gas molecule adsorption in a humid atmosphere influences the pH and thus the surface charge density on the SiO₂ shell, causing changes in the low-frequency noise level via electrostatic interactions.