Band-edge exciton states in bulk lead chalcogenides are 64-fold degenerate. In quantum dots (QDs), the degeneracy is lifted by the valley mixing and the electron-hole exchange interaction. To investigate their interplay we calculate excitonic states in PbS QDs within the tight-binding method. This allows one to trace the genesis of the bright excitonic states from the valley-degenerate states of the direct exciton which may be described within the effective mass model. We compute optical absorption spectra fully accounting for the exciton fine structure within the tight-binding method and extend the effective-mass model to include description of the inter-valley coupling.

Date Published: 31 January 2020
PDF: 7 pages
Proc. SPIE 11288, Quantum Sensing and Nano Electronics and Photonics XVII, 112880S (31 January 2020); doi: 10.1117/12.2542847

Published in SPIE Proceedings Vol. 11288:
Quantum Sensing and Nano Electronics and Photonics XVII
Manijeh Razeghi; Jay S. Lewis; Giti A. Khodaparast; Pedram Khalili, Editor(s)