Enhanced Raman scattering and weak localization in graphene deposited on GaN nanowires

Jakub Kierdaszuk, Piotr Kaźmierczak, Aneta Drabińska, Krzysztof Korona, Agnieszka Wołoś, Maria Kamińska, Andrzej Wysmołek, Iwona Pasternak, Aleksandra Krajewska, Krzysztof Pakuła, and Zbigniew R. Zytkiewicz
Phys. Rev. B 92, 195403 – Published 5 November 2015

Abstract

The influence of GaN nanowires on the optical and electrical properties of graphene deposited on them was studied using Raman spectroscopy and a microwave-induced electron transport method. It was found that the interaction with the nanowires induces spectral changes and leads to a significant enhancement of the Raman scattering intensity. Surprisingly, the smallest enhancement (about 30-fold) was observed for the defect induced D′ process, and the highest intensity increase (over 50-fold) was found for the 2D transition. The observed energy shifts of the G and 2D bands allowed us to determine the carrier concentration fluctuations induced by the GaN nanowires. A comparison of the Raman scattering spatial intensity maps and the images obtained using a scanning electron microscope led to a conclusion that the vertically aligned GaN nanowires induce a homogenous strain, substantial spatial modulation of the carrier concentration in graphene, and unexpected homogenous distribution of defects created by the interaction with the nanowires. The analysis of the D and D′ peak intensity ratio showed that the interaction with the nanowires also changes the probability of scattering on different types of defects. The Raman studies were correlated with the weak localization effect measured using microwave-induced contactless electron transport. The temperature dependence of the weak localization signal showed electron-electron scattering as the main decoherence mechanism with an additional, temperature-independent scattering-reducing coherence length. We attributed it to the interaction of electrons in graphene with charges present on top of nanowires due to the spontaneous and piezoelectric polarization of GaN. Thus, nanowires act as antennas and generate an enhanced near field, which can explain the observed significant enhancement of the Raman scattering intensity.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Received 5 July 2015
  • Revised 1 October 2015

DOI:https://doi.org/10.1103/PhysRevB.92.195403

©2015 American Physical Society

Authors & Affiliations

Jakub Kierdaszuk1,*, Piotr Kaźmierczak1, Aneta Drabińska1, Krzysztof Korona1, Agnieszka Wołoś1,2, Maria Kamińska1, Andrzej Wysmołek1, Iwona Pasternak3, Aleksandra Krajewska3,4, Krzysztof Pakuła1, and Zbigniew R. Zytkiewicz2

  • 1Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02–093, Warsaw, Poland
  • 2Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02–668, Warsaw, Poland
  • 3Institute of Electronic Materials Technology, ul. Wólczyńska 133, 01–919, Warsaw, Poland
  • 4Institute of Optoelectronics, Military University of Technology, ul. Gen. Sylwestra Kaliskiego 2, 01–476, Warsaw, Poland

  • *Author to whom correspondence should be addressed: jakub.kierdaszuk@fuw.edu.pl

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 92, Iss. 19 — 15 November 2015

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review B

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×