Study of Absorption Spectra of Excitons in Cu₂O by Wavelength Modulation Technique

Abstract

The wavelength derivative absorption spectra of Cu₂O have been measured in the energy regions of the yellow and green exciton series over a wide temperature range. Three phonon assisted indirect transition edges are newly found at 4.2 K, and the structures associated with direct transitions to the 1s state and the higher exciton states are observable up to room temperature. By analysing the impurity associated transition and using the Rydberg constants for both the yellow and the green exciton series, we determine the effective mass of the electron in the conduction band and those of the holes in the valence bands to be m_e^*\simeq0.99m₀, m_lh^*\simeq0.64m₀ (light hole) and m_hh^*\simeq1.40m₀ (heavy hole).