Tunable Electrical Properties of Silicon Nanowires via Surface-Ambient Chemistry

Abstract

p-Type surface conductivity is a uniquely important property of hydrogen-terminated diamond surfaces. In this work, we report similar surface-dominated electrical properties in silicon nanowires (SiNWs). Significantly, we demonstrate tunable and reversible transition of p(+)-p-i-n-n(+) conductance in nominally intrinsic SiNWs via changing surface conditions, in sharp contrast to the only p-type conduction observed on diamond surfaces. On the basis of Si band energies and the electrochemical potentials of the ambient (pH value)-determined adsorbed aqueous layer, we propose an electron-transfer-dominated surface doping model, which can satisfactorily explain both diamond and silicon surface conductivity. The totality of our observations suggests that nanomaterials can be described as a core-shell structure due to their large surface-to-volume ratio. Consequently, controlling the surface or shell in the core-shell model represents a universal way to tune the properties of nanostructures, such as via surface-transfer doping, and is crucial for the development of nanostructure-based devices.

Geometric and chemical components of the giant piezoresistance in silicon nanowires

“…2(a). The p-type nature of the SiNWs is not due to the Boron acceptors which require a vacuum anneal for re-activation [24], but is consistent with the creation of acceptor-like interface defects by HNO 3 oxidation [25,26]. While the PZR is positive and linear as expected for p-Si, its magnitude is significantly larger than π bulk (see dashed, black line in Fig.…”

Probing the electronic structure at semiconductor surfaces using charge transport in nanomembranes

“…In the current measurements, the free surface is atomically clean, but that is not a requirement for general application of the method. Any changes 4,[11][12][13] in the front surface act as an additional gate to counter or enhance the effect of the back gate. The NM bulk conductance is continuously tunable by the back-gate voltage and hence can be made negligible relative to the surface contribution.…”

Electrochemically Induced p-Type Conductivity in Carbon Nanotubes

“…16 Much of the understanding of the effect comes from the study of the p-type surface conductivity of diamond exposed to humid air. [17][18][19][20] Transfer doping has also been observed in GaN and ZnO, 21 in Si nanowires, 22 and has recently been reviewed by Chen et al 23 Electrochemical surface transfer doping.-Adsorbed water films on solids exposed to humid air are well known 24 and the subject of major reviews. 25,26 Even highly hydrophobic surfaces can have up to three monolayers of adsorbed water at high humidity.…”