Wavelength modulated excitonic spectra of Cu2O thin films sandwiched by MgO plates
We have investigated stress effects on yellow exciton states in a Cu2O thin film sandwiched by MgO plates by measuring wavelength modulated (WM) absorption spectra and their thermal variations. In the WM absorption spectra, dispersive spectral structures owing to 2P~4P states in the yellow excitons are clearly resolved in the thin film sample. A stress due to the lattice mismatch between Cu2O and MgO provides a large red shift of the band gap in the green excitonic system. However, in the yellow excitonic transitions, it is found that a red-shift of the 2P excitonic state is much smaller than that in the green excitonic system. This result suggests that a shallow potential minimum for the yellow excitons is built up in the Cu2O thin film sandwiched by MgO plates.
- 1.S.A. Moskalenko, D.W. Snoke, Bose-Einstein Condensa- tion of Excitons and Biexcitons: and Coherent Nonlinear Optics with Excitons (Cambridge University Press, Cambridge, 2005)Google Scholar
- 9.N. Naka, Ph.D. thesis, Department of Physics, Graduate School of Science, The University of Tokyo, 2002Google Scholar
- 18.G.L. Squires, Practical Physics, 4th edn. (Cambridge University Press, Cambridge, 2001)Google Scholar