Multi-Dimensional Photoemission Spectroscopy of Semiconductor Heterostructures—Resolving Photoelectrons in Space, Time, Momentum and Energy

Photoemission spectroscopy - the family of techniques in which one measures the properties of an electron photoemitted from the sample by a high energy photon, provides direct knowledge about the electronic structure of the material. Angle-resolved photoemission spectroscopy (ARPES) and Photoemission electron microscopy (PEEM) are two powerful examples that probe momentum- and real-space respectively. Over the past decade, it has become possible to combine aspects of these techniques, along with ultrafast pump-probe techniques, to simultaneously resolve the temporal-, spatial-, momentum- and spectral-coordinates of the photoemitted electron.<br/><br/>In this talk, I will discuss our applications of these techniques to image the performance limiting defect states in perovskite photovoltaic materials [1, 2, 3, 4] and to study momentum-resolved exciton dynamics in microscopic samples two-dimensional semiconductor heterostructures [5, 6, 7].<br/><br/>References<br/>[1] M. K. L. Man, <i>et al.</i> <i>Nature Nanotechnol.</i> <b>12</b>, 36 (2017)<br/>[2] T. Doherty^*, A. Winchester^*, <i>et al.</i> <i>Nature</i> <b>580</b>, 360 (2020)<br/>[3] S. Kosar, <i>et al.</i> <i>Energy and Environment Sciences</i>, DOI: 10.1039/d1ee02055b (2021)<br/>[4] S. Macpherson, <i>et al.</i> <i>arXiv:</i> 2107.09549 (2021)<br/>[5] J. Madeo^*, M. K. L. Man^*, <i>et al.</i> <i>Science</i> <b>370</b>, 1199 (2020).<br/>[6] M. K. L. Man^*, J. Madeo^*, <i>et al.</i> <i>Science Advances</i> <b>7</b>, eabg0192 (2021).<br/>[7] O Karni^*, E. Barr^*, V. Pareek^*, J. D. Georgaras^*, M. K. L. Man^*, C. Sahoo^*, <i>et al.</i> <i>arXiv</i>:2108.01933 (2021)<br/>^* equal authors