Coherent dynamics and mapping of excitons in single-layer <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>MoSe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>WSe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> at the homogeneous limit
Caroline Boule, Diana Vaclavkova, Miroslav Bartos, Karol Nogajewski, Lukas Zdražil, Takashi Taniguchi, Kenji Watanabe, Marek Potemski, Jacek Kasprzak
Abstract
Embedding 2D materials, namely single-layers of MoSe${}_{2}$ or WSe${}_{2}$, between thin layers of hexagonal boron nitride of supreme quality suppresses the structural disorder and avoids surface contamination. As a result, the optical properties of such heterostructures improve drastically with respect to unprotected samples, approaching characteristics expected for ideal 2D crystals. Yet, how can one tell if the spectral line-shape of optical transitions is measured free from the disturbing and mostly irrelevant features introduced by the disorder? Do I really observe the intrinsic (the so-called, homogeneous) linewidth in linear absorption or emission? If yes, what are the spatial extensions on which such optimal conditions can be maintained? The authors here employ methods of nonlinear spectroscopy to accurately address these questions.