Stimulated emission from exciton–exciton scattering in CuBr thin films

• Published in: Journal of luminescence 2000-05, Vol.87, p.235-237
• Main Authors: Ichida, H, Nakayama, M, Nishimura, H
• Format: Article
• Language: English
• Subjects: Collective excitations (including excitons, polarons, plasmons and other charge-density excitations); Collective excitations (including plasmons and other charge-density excitations); Condensed matter: electronic structure, electrical, magnetic, and optical properties; CuBr; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Exciton–exciton scattering; Insulators; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics; Stimulated emission; Surface and interface electron states; Thin film
• ISSN: 0022-2313; 1872-7883
• DOI: 10.1016/S0022-2313(99)00272-0

We have investigated the photoluminescence properties under intense-excitation conditions in a CuBr thin film with the thickness of 100 nm grown on a (0 0 0 1) Al 2O 3 substrate by a vacuum deposition method. We have detected a new photoluminescence band with the intensity dependence on the excitation power exhibiting threshold behavior and almost quadratic characteristics. The threshold power at excitation by a pulsed nitrogen laser is ∼8 μJ/cm 2 at 10 K, and the emission energy is lower than that of the n=1 free exciton by the energy difference of the n=1 and 2 excitons. In addition, we have observed the optical gain in the energy region of the new photoluminescence band. From the above results, we conclude that the new photoluminescence band results from the stimulated emission due to the inelastic scattering between n=1 excitons, so-called P 2 emission.