Carrier mobility of silicon by sub-bandgap time-resolved terahertz spectroscopy

Published

February 26, 2020

Author(s)

Timothy J. Magnanelli, Edwin J. Heilweil

Abstract

Low density charge mobility from below bandgap, two-photon photoexcitation of bulk Silicon (Si) is interrogated using time-resolved terahertz spectroscopy (TRTS). Total charge mobility is measured as a function of excitation frequency and fluence (charge carrier density), cut angle, and innate doping levels. Frequency dependent complex photoconductivities are extracted using the Drude model to obtain average and DC limit mobility and carrier scattering lifetimes. These dynamic parameters are compared to values from contact-based Hall, above bandgap photoexcitation, and comparable gallium arsenide (GaAs) measurements. Mobilities are shown to increase beyond Hall values at low carrier densities and are modestly higher with increasing dopant density. The former occurs in part from below bandgap photoexcitation exhibiting abnormally small (faster) scattering lifetimes, while both reflect unique conduction characteristics at lowest (ca. > 2x1012 cm-3) carrier densities achieved through photodoping.

Citation

Optics Express

Volume

28

Issue

5

Pub Type

Journals

Download Paper

https://doi.org/10.1364/OE.382840

Local Download

Keywords

ultrafast spectroscopy, terahertz, semiconductor, silicon, mobility

Citation

Magnanelli, T. and Heilweil, E. (2020), Carrier mobility of silicon by sub-bandgap time-resolved terahertz spectroscopy, Optics Express, [online], https://doi.org/10.1364/OE.382840, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=928833 (Accessed October 9, 2025)