Detection of Deep-Levels in Doped Silicon Nanowires Using Low-Frequency Noise Spectroscopy

We report detailed characterization of electrically-active deep-levels in doped Si nanowires (SiNWs) grown using catalyst-assisted vapor-liquid-solid (VLS) technique. Temperature-dependent low-frequency noise (LFN) spectroscopy was used to reveal the presence of generation-recombination related Lorentzian-type peaks along with 1/f-type noise in these NWs. In Ni-catalyzed SiNWs, the correlated LFN spectroscopy detected electrically active deep-levels with ionization energies of 0.42 eV for the n-type and 0.22 eV for the p-type SiNWs, respectively. In Au-catalyzed n- and p-type SiNWs, the energies of the deep-levels were estimated to be 0.44 and 0.38 eV, respectively. These values are in good agreement with the known ionization energies of deep-levels introduced by Ni and Au in Si. Associated trap concentrations and hole and electron capture cross sections were also estimated. This paper clearly indicated the presence of electrically active deep-levels associated with unintentional incorporation of catalyst atoms in the VLS-grown SiNWs.