Enhanced Raman scattering and weak localization in graphene deposited on GaN nanowires
PBN-AR
Instytucja
Instytut Fizyki Polskiej Akademii Nauk
Informacje podstawowe
Główny język publikacji
en
Czasopismo
PHYSICAL REVIEW B
ISSN
1098-0121
EISSN
1550-235X
Wydawca
AMER PHYSICAL SOC
DOI
URL
Rok publikacji
2015
Numer zeszytu
Strony od-do
195403
Numer tomu
92
Identyfikator DOI
Liczba arkuszy
Słowa kluczowe
en
GaN nanowires graphene Raman spectroscopy microwave induced contactless electron transport electron scattering defects
Streszczenia
Język
en
Treść
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.
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Original article
Original article presents the results of original research or experiment.
Inne
System-identifier
PBN-R:668927
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