Growth, characterization, and optical spectroscopy of copper cloride quantum well structures

The first CuCl quantum well structures of the type CaF;The optical properties of the CuCl films have been characterized by low-temperature absorption, excitation, and excitation-density dependent photoluminescence. Striking differences in the excitonic emission spectra are observed between the quantum well structures and a bulk single crystal sample of CuCl. Excitons were also formed by irradiation of these structures with UV frequencies above the CuCl bandgap, and the spectral and temporal dependences of the recombination radiation were compared to those of a bulk CuCl single crystal. The photoluminescence lineshapes of the free excitons in the thin films were characteristic of a much hotter exciton temperature and of much shorter lifetimes (;Stimulated emission is observed from a 30A CuCl quantum well structure created by a two-photon resonant Raman dye laser excitation and attributed to the radiative recombination of the excitonic molecule to yield two photons. Photoluminescence measurements from a 12A CuCl quantum well structure, excited by a continuous wave Ar-ion laser, show a marked increase in emission from the region characteristic of excitonic molecule recombination compared to previous investigations. A Stokes shift of the free exciton photoluminescence is observed from the sample which arises from non-uniformities at the interfaces between the potential barriers and the semiconductor.;Thin films of CuCl were deposited by molecular beam epitaxy directly onto a room temperature Si(111)-7 x 7 substrate and studied with surface sensitive spectroscopies. Ion scattering experiments indicated that the initial stage of CuCl growth involved Cl-Si bonding. Annealing the films initiated chemical reactions, which resulted in the loss of Cl and the formation of a Cu silicide.