Quantum size phenomena in single-crystalline bismuth nanostructures

TL;DR

This paper demonstrates size-dependent quantum effects in bismuth nanostructures, showing non-monotonous conductivity changes and a metal-insulator transition at nanoscale dimensions, relevant for nanoelectronic device optimization.

Contribution

It provides experimental evidence of quantum size phenomena in bismuth nanostructures and links these effects to potential applications in nanoelectronics.

Findings

Conductivity decreases non-monotonously with size reduction.

Abrupt increase in conductivity at ~50 nm due to metal-insulator transition.

Findings align with theoretical predictions.

Abstract

Size-dependent quantization of energy spectrum of conducting electrons in solids leads to oscillating dependence of electronic properties on corresponding dimension(s). In conventional metals with typical energy Fermi EF~1 eV and the charge carrier's effective masses m* of the order of free electron mass m0, the quantum size phenomena provide noticeable impact only at nanometer scales. Here we experimentally demonstrate that in single-crystalline semimetal bismuth nanostructures the electronic conductivity non-monotonously decreases with reduction of the effective diameter. In samples grown along the particular crystallographic orientation the electronic conductivity abruptly increases at scales of about 50 nm due to metal-to-insulator transition mediated by the quantum confinement effect. The experimental findings are in reasonable agreement with theory predictions. The quantum-size phenomena should be taken into consideration to optimize operation of the next generation of ultra-small quantum nanoelectronic circuits.