Efficient photogeneration of charge carriers in silicon nanowires with a radial doping gradient

TL;DR

This study demonstrates that radial doping gradients in silicon nanowires significantly enhance charge carrier photogeneration, mobility, and lifetime, driven by internal electric fields from impurity incorporation during growth.

Contribution

It introduces a method to improve charge carrier generation in silicon nanowires through radial doping gradients, revealing the role of internal electric fields.

Findings

Enhanced photoconductance and charge carrier lifetime with impurity doping

Internal electric fields from doping gradients influence charge dynamics

Detailed analysis links nanowire morphology to electrical properties

Abstract

From electrodeless time-resolved microwave conductivity measurements, the efficiency of charge carrier generation, their mobility, and decay kinetics on photo-excitation were studied in arrays of Si nanowires grown by the vapor-liquid-solid mechanism. A large enhancement in the magnitude of the photoconductance and charge carrier lifetime are found depending on the incorporation of impurities during the growth. They are explained by the internal electric field that builds up, due to a higher doped sidewalls, as revealed by detailed analysis of the nanowire morphology and chemical composition.