Abstract
Group IV semiconductor nanowires have been investigated experimentally and theoretically for several years. Their intriguing and yet not fully understood properties and the potential for applications in nanoelectronics, spintronics, energy harvesting, production and storage, sensors, and neuroelectronics motivate this research effort. Due to the high surface area SiNWs and GeNWs represent also a perfect material science lab to investigate with high accuracy specific issues related to defects and interfaces. The investigation of defects at the interface between silicon and silicon oxide becomes very important when the SiNW diameter reduces below 10-20 nm and the surface-to-volume ratio increases [1, 2]. In the present work we focus on the investigation of the doping of silicon nanowires addressing the role of hydrogen, as well as other passivating species, and Pb defects at the Si/SiO2 interface [3-5] in the donor deactivation mechanisms and the role of the confinement and dielectric mismatch in determining the donor electronic wave function. To address these intriguing issues we have used different complementary experimental techniques such as electron paramagnetic resonance (EPR), both continuous wave and pulsed, FT-IR, and MD-PICTS. Silicon nanowires have been produced by metal-assisted chemical etching (MACE) [6, 7] using either Ag nanoparticles or a thin Au layer as catalyst and further processing has been used to reduce the size of the nanowires. The reported results are relevant for the wide range of applications exploiting the peculiar silicon nanowires electronic properties and surface reactivity. GeNWs and core-shell heterostructures (Si/Ge) produced by vapor-liquid-solid growth have been also investigated and results on the dominant defects in these nanostructures will be discussed.
References:
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