Towards higher electron mobility in modulation doped GaAs/AlGaAs core shell nanowires

Jessica L. Boland, Gözde Tütüncüoglu, Juliane Q. Gong, Sonia Conesa-Boj, Christopher L. Davies, Laura M. Herz, Anna Fontcuberta Morral, Michael B. Johnston*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

10 Citations (Scopus)
38 Downloads (Pure)

Abstract

Precise control over the electrical conductivity of semiconductor nanowires is a crucial prerequisite for implementation of these nanostructures into novel electronic and optoelectronic devices. Advances in our understanding of doping mechanisms in nanowires and their influence on electron mobility and radiative efficiency are urgently required. Here, we investigate the electronic properties of n-type modulation doped GaAs/AlGaAs nanowires via optical pump terahertz (THz) probe spectroscopy and photoluminescence spectroscopy over the temperature range 5 K-300 K. We directly determine an ionization energy of 6.7 ± 0.5 meV (T = 52 K) for the Si donors within the AlGaAs shell that create the modulation doping structure. We further elucidate the temperature dependence of the electron mobility, photoconductivity lifetime and radiative efficiency, and determine the charge-carrier scattering mechanisms that limit electron mobility. We show that below the donor ionization temperature, charge scattering is limited by interactions with interfaces, leading to an excellent electron mobility of 4360 ± 380 cm2 V-1 s-1 at 5 K. Above the ionization temperature, polar scattering via longitudinal optical (LO) phonons dominates, leading to a room temperature mobility of 2220 ± 130 cm2 V-1 s-1. In addition, we show that the Si donors effectively passivate interfacial trap states in the nanowires, leading to prolonged photoconductivity lifetimes with increasing temperature, accompanied by an enhanced radiative efficiency that exceeds 10% at room temperature.

Original languageEnglish
Pages (from-to)7839-7846
JournalNanoscale
Volume9
Issue number23
DOIs
Publication statusPublished - 2017

Fingerprint

Dive into the research topics of 'Towards higher electron mobility in modulation doped GaAs/AlGaAs core shell nanowires'. Together they form a unique fingerprint.

Cite this