Identification of Excitons and Biexcitons in Sb2Se3 under High Photoluminescence Excitation Density. Issue 10 (10th March 2021) - Krustok, Jüri
Abstract: The near‐band‐edge emission of Sb2 Se3 microcrystals is studied in detail under high photoluminescence excitation density using a pulsed UV laser (λ = 266 nm, pulse width 0.6 ns). Based on the peak energy positions and the excitation power density and temperature dependencies ( T = 3–110 K) of the photoluminescence spectra, the emission is interpreted as a recombination of two pairs (A and B) of free excitons and biexcitons appearing because of valence band splitting. The magnitude of the valence band splitting due to the crystal field (Δcr = 20–22 meV) is estimated in the Brillouin zone center. At T = 3 K, the A and B biexciton emission at 1.302 and 1.322 eV, respectively, and the A and B free exciton emission at 1.311 and 1.333 eV, respectively, are observed. The binding energy of A and B biexcitons is 9 and 11 meV, respectively, and the binding energy of A free exciton is 6 meV. The activation energy of thermal quenching for all observed peaks is 20 meV. Abstract : This paper presents a detailed study of free exciton and biexciton emissions in Sb2 Se3 microcrystals. Due to the crystal field splitting of the valence band, two different free exciton photoluminescence peaks and two different biexciton peaks at T = 3 K are observed: XA, XB, XXA, and XXB centered at 1.311, 1.333, 1.302, and 1.322 eV, respectively.