Selective Raman modes and strong photoluminescence of gallium selenide flakes on sp2 carbon

Raul D. Rodriguez, Susanne Müller, Evgeniya Sheremet, Dietrich R.T. Zahn, Alexander Villabona, Santos A. Lopez-Rivera, Philipp Tonndorf, Steffen Michaelis De Vasconcellos, Rudolf Bratschitsch

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Two-dimensional materials awakened a strong interest in the scientific and technological communities due to their exceptional properties that can be tuned by the material thickness and chemistry. In order to correlate optical properties with crystallographic structure and morphology, in this work, the authors aim at studying GaSe nanoflakes deposited on highly ordered pyrolytic graphite by means of atomic force microscopy, Raman, and photoluminescence (PL) spectroscopies. The authors found that the basal plane of the flakes can be attributed to the ε-phase expected for bulk samples grown by the Bridgman method. However, a strong difference in the Raman spectra was systematically found at the edge of our GaSe flakes. Forbidden Raman modes located around 250 cm-1 were selectively observed at specific locations. These modes could not be directly attributed to the ε-phase observed in the basal plane or in the bulk. The atomic force microscopy investigations show that high topographical features characterize the regions with the highest photoluminescence and the forbidden Raman modes. This change in crystal orientation at selective locations of the flake could activate the E′(LO) Raman mode at 255 cm-1. The enhancement of the PL emission around 620 nm is also linked to the change in crystal orientation due to an increase in the probability of electronic transitions. These results show the rich physics of GaSe flakes in contrast to what is known from its bulk counterpart with possible applications in photovoltaics and photodetectors for nanoflakes with engineered geometries.

Original languageEnglish
Article number04E106
JournalJournal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures
Volume32
Issue number4
DOIs
Publication statusPublished - 1 Jan 2014
Externally publishedYes

Fingerprint

gallium selenides
flakes
Gallium
Crystal orientation
Atomic force microscopy
Photoluminescence
photoluminescence
Crystal growth from melt
Carbon
Photoluminescence spectroscopy
carbon
Photodetectors
Raman spectroscopy
Raman scattering
Graphite
Physics
Optical properties
atomic force microscopy
Bridgman method
Geometry

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electrical and Electronic Engineering

Cite this

Selective Raman modes and strong photoluminescence of gallium selenide flakes on sp2 carbon. / Rodriguez, Raul D.; Müller, Susanne; Sheremet, Evgeniya; Zahn, Dietrich R.T.; Villabona, Alexander; Lopez-Rivera, Santos A.; Tonndorf, Philipp; De Vasconcellos, Steffen Michaelis; Bratschitsch, Rudolf.

In: Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures, Vol. 32, No. 4, 04E106, 01.01.2014.

Research output: Contribution to journalArticle

Rodriguez, Raul D. ; Müller, Susanne ; Sheremet, Evgeniya ; Zahn, Dietrich R.T. ; Villabona, Alexander ; Lopez-Rivera, Santos A. ; Tonndorf, Philipp ; De Vasconcellos, Steffen Michaelis ; Bratschitsch, Rudolf. / Selective Raman modes and strong photoluminescence of gallium selenide flakes on sp2 carbon. In: Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures. 2014 ; Vol. 32, No. 4.
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