CC BY
23LD-I-11
Plasmon-enhanced optical spectroscopies of semiconductor
nanostructures
A.G. Milekhin1'2, M. Rahaman3, T.A. Duda1, E.E. Rodyakina12, R.B.Vasiliev4, I.A. Milekhin3, K.V. Anikin1, S.A. Kuznetsov1, V.G. Mansurov1, A.V. Latyshev12, D.R.T. Zahn3
1 A.V. Rzhanov Institute of Semiconductor Physics, 630090, Novosibirsk, Lavrentjev av. 13, Russia 2 Novosibirsk State University, Novosibirsk, 630090, Pirogov str., 1, Russia 3 Semiconductor Physics, Chemnitz University of Technology, D-09107 Chemnitz, Germany 4 Department of Material Science, Moscow State University, Moscow, Russia
milekhin@isp. nsc. ru
The results of a Tip-Enhanced Raman Scattering (TERS) and Surface-Enhanced InfraRed Absorption (SEIRA) study of CdSe nanocrystals (NCs) and CdSe/CdS nanoplatelets (NPLs) on arrays of Au nanodiscs and nanoantennas fabricated using nanolithography are discussed. In addition, the perspectives of nano-IR spectroscopy for hyperspectral infrared nanoimaging of AlN nanocolumns are also considered.
Monolayers (MLs) of CdSe NCs with a size of 5-6 nm and sub-MLs of CdSe/CdSe NPLs consisting of 1.5 nm CdSe core and 0.6 nm CdS shell were deposited on plasmonic substrates using the Langmuir-Blodgett technology.
TERS by longitudinal optical (LO) and surface optical (SO) phonons in CdSe-based nanostructures placed in the gap between the TERS tip apex and Au nanodisks was observed. The TERS signal from MLs of CdSe NCs on Au nanodisk arrays forms a pattern of ordered rings with a diameter equal or below that of the Au nanodisks dependent on the excitation energy. A superposition of the TERS image on the corresponding AFM topography shows that the centers of the rings and Au nanodisks perfectly coincide. This indicates a strong dependency of TERS phonon mode intensity on the LSPR energy of the coupled system of the tip and the nanodisk and their relative position as well as evidences the electromagnetic mechanism of TERS.
TERS maps for CdSe/CdS NPLs reproducing the size and shape of the NPLs are consistent with AFM
images and allowed the phonon spectrum of single NCs and NPL to be investigated.
SEIRA by optical phonons of MLs of CdSe-based nanostructures on Au nanoantennas with structural
parameters allowing the coupling to the LSPR modes is discussed. The frequency positions of the
absorption features evidence that the SO phonons of MLs of CdSe/CdS NPLs are active in the SEIRA
spectra.
We also present the results of the hyperspectral infrared nanoimaging of AlN nanocolumns based on fourier transform infrared nanospectroscopy. AlN nanocolumns with a diameter and height of about 200 and 50 nm, respectively, were grown by molecular-beam epitaxy. IR nanospectroscopy allows the spatial localization of optical phonon modes with different symmetry in AlN to be studied.
Acknowledgements
The reported study was funded by Volkswagen Foundation and RFBR in the research projects 19-5212041 NNIO and 18-29-20066 mk.
