Excitonic complexes in n-doped WS2 monolayer
Abstract
We investigate the origin of emission lines apparent in the low-temperature photoluminescence spectra of n-doped WS2 monolayer embedded in hexagonal BN layers using external magnetic fields and first-principles calculations. Apart from the neutral A exciton line, all observed emission lines are related to the negatively charged excitons. Consequently, we identify emissions due to both the bright (singlet and triplet) and dark (spin- and momentum-forbidden) negative trions as well as the phonon replicas of the latter optically-inactive complexes. The semi-dark trions and negative biexcitons are distinguished. Based on their experimentally extracted and theoretically calculated g-factors, we identify three distinct families of emissions due to exciton complexes in WS2: bright, intravalley and intervalley dark. The g-factors of the spin-split subbands in both the conduction and valence bands are also determined.