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

Research output: Contribution to journalArticle

  • External authors:
  • Gozde Tutuncuoglu
  • Juliane Q. Gong
  • Sonia Conesa-Boj
  • Christopher L. Davies
  • Laura M. Herz
  • Anna Fontcuberta i Morral
  • Michael B. Johnston

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.

Bibliographical metadata

Original languageEnglish
Pages (from-to)7839-7846
JournalNanoscale
Volume9
Issue number23
Early online date17 May 2017
DOIs
Publication statusPublished - 21 Jun 2017

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