講演情報
[17p-M_178-5]Large-area homogeneity of exciton luminescence in high-quality suspended WSe2 monolayers
〇Giacomo Mariani1, Keigo Matsuyama1, Yoji Kunihashi1, Taro Wakamura1, Satoshi Sasaki1, Makoto Kohda2,3,4, Junsaku Nitta1,2, Haruki Sanada1 (1.NTT-BRL, 2.Tohoku Univ., 3.CSIS, 4.QST)
キーワード：
2D materials、suspended monolayer、exciton
Transition-metal dichalcogenide (TMD) monolayers are an emerging platform for excitonic and spin–valley physics in two dimensions. However, their optical response is often spectrally broadened and spatially nonuniform due to substrate disorder, charge fluctuations, and strain gradients introduced during fabrication and transfer. Encapsulation in hexagonal boron nitride (hBN) can strongly improve linewidths, but the usable high-quality area is often limited to a few micrometers. Large and spectrally uniform regions are therefore required to access intrinsic exciton physics and enable long-range exciton/valley transport studies. Suspended monolayers provide a contact-free geometry that can reveal intrinsic behavior while enabling electromechanical tuning.Here we report large-area spectral homogeneity in suspended WSe2 monolayers prepared by contamination-minimized gold-assisted exfoliation. A smooth Au electrode is cleaned immediately before exfoliation, reducing interfacial residues and avoiding polymer-assisted transfer. The resulting monolayers span narrow suspended regions over tens of micrometers, enabling systematic spatial mapping. Cryogenic photoluminescence mapping at T ≈ 7 K shows that the neutral exciton energy varies by less than 1 meV across the central region, while the linewidth remains nearly constant with FWHM ≈ 4–5 meV. Variations increase near clamped edges, consistent with localized boundary strain, whereas the central region remains highly homogeneous. The homogeneous area extends over several micrometers, often larger than the usable uniform region in encapsulated monolayers, supporting intrinsic exciton studies and long-range valley experiments as well as transport and optomechanical concepts requiring a uniform energy landscape.