CC BY
0Raman spectroscopy and photoluminescence of semiconductor nanostructures with nanometer spatial resolution
A.G. Milekhin1*, I.A. Milekhin1'2, N.N. Kurus1, L.S. Basalaeva1, R.B. Vasiliev3, A.V. Latyshev12, D.R.T. Zahn4
1-A.V Rzhanov Institute of Semiconductor Physics, 630090, Novosibirsk, Lavrentjev av. 13, Russia 2- Novosibirsk State University, Novosibirsk, 630090, Pirogov str., 1 3- Department of Material Science, Moscow State University, Moscow, Russia 4- Russia Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany
* milekhin@isp.nsc.ru
Tip-enhanced Raman scattering and photoluminescence (TERS and TEPL, respectively) taking advantages of conventional micro-Raman and -PL spectroscopies and atomic-force microscopy allow to study the phonon and electron spectra of semiconductor nanostructures with the nanometer spatial resolution and to derive information of their local properties such as built-in mechanical strain or structural defects.
Here, the results of TERS and TEPL study of GaAs nanocrystals (NCs) and nanocolumns, as well as graphene flakes and monolayers of metal chalcogenides (MoS2 and WS2) are presented.
AFM images, TERS, TEPL, and conventional micro-Raman as well as micro-PL spectra were obtained using an AFM AIST-NT coupled with a Raman spectrometer (Xplora, Horiba). All PL and Raman spectra were recorded using an objective (100*, 0.7 NA) at normal light incidence under laser excitation with a wavelength of 638 and 532 nm at room temperature. TERS probes metallized with Au or Ag were used in the experiments.
TEPL imaging of single GaAs NCs and nanocolumns with a spatial resolution of about 10 nm that is much below the diffraction limit is performed. It is shown that localized surface plasmon resonance originated at metallized TERS tip can be effectively used for imaging of single GaAs nanostructures. TERS by vibrational modes from arsenic nanoclusters allows their spatial distribution over the GaAs NC surface to be established.
On the base of the analysis of TERS and TEPL spectra for atomically thin MoS2 and WS2 islands, the size, shape of the nanostructures as well as their structural defects and built-in mechanical strain are established. For further enhancement of the optical response, graphene and MoS2 monolayers were transferred on the plasmonic substrate consisting of Au nanodisk array for which the gap-mode plasmon TERS is realized [1]. It is shown that the local built-in mechanical strain in the MoS2 monolayer deposited on an Au nanocluster can be locally changed on the scale of about 2 nm reaching a value of -2%.
Acknowledgements
This work was supported by the Russian Science Foundation (project 22-12-00302).
[1] N.N. Kurus, V. Kalinin, N.A. Nebogatikova, et al, Resonant Raman Scattering on Graphene: SERS and gap-mode TERS, RCS Advances,
vol. 14, pp. 3667-3674, (2024).
