title: Bound exciton and free exciton states in GaSe thin slab.
abstract: The photoluminescence (PL) and absorption experiments have been performed in GaSe slab with incident light polarized perpendicular to c-axis of sample at 10 K. An obvious energy difference of about 34 meV between exciton absorption peak and PL peak (the highest energy peak) is observed. By studying the temperature dependence of PL and absorption spectra, we attribute it to energy difference between free exciton and bound exciton states, where main exciton absorption peak comes from free exciton absorption, and PL peak is attributed to recombination of bound exciton at 10 K. This strong bound exciton effect is stable up to 50 K. Moreover, the temperature dependence of integrated PL intensity and PL lifetime reveals that a non-radiative process, with activation energy extracted as 0.5 meV, dominates PL emission.
authors.affiliation: Department of Physics, South University of Science and Technology of China, Shenzhen 518055, China.
authors.forename: Chengrong
authors.initials: C
authors.lastname: Wei
authors.affiliation: Physics Department, The University of Hong Kong, Pokfulam road, Hong Kong, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.affiliation: Physics Department, The University of Hong Kong, Pokfulam road, Hong Kong, China.
authors.forename: Dian
authors.initials: D
authors.lastname: Li
authors.affiliation: Department of Physics, South University of Science and Technology of China, Shenzhen 518055, China.
authors.forename: Huimin
authors.initials: H
authors.lastname: Su
authors.affiliation: Department of Physics, South University of Science and Technology of China, Shenzhen 518055, China.
authors.forename: Hongtao
authors.initials: H
authors.lastname: He
authors.affiliation: Department of Physics, South University of Science and Technology of China, Shenzhen 518055, China.
authors.forename: Jun-Feng
authors.initials: JF
authors.lastname: Dai