Series Of Cu2O Research Articles

Electroabsorption in the yellow exciton series of Cu 2O

The influence of an external electric field on the yellow series of Cu 2O, using a modulation technique has been studied. The structures observed in electroabsorption spectra are due essentially to exciton transitions.

Energy band structure of Cu 2O in the vicinity of the fundamental edge from magneto-oscillatory absorption measurements

Experimental oscillatory magneto-optical absorption data are presented for the yellow series of Cu 2O at 1.5° K. These data indicate that the top of the valence band is of Г + 8 symmetry. A reduced hole-electron effective mass μ = 0.41 m and a dielectric constant ϵ = 7.6 are determined.

Etude spectrophotometrique des spectres continus de Cu 2O a diverses temperatures

The absorption of samples of different thicknesses (from 10 to 180 μ) of synthetic Cu 2O has been measured at different temperatures (293°K, 249°K, 169°K, 104°K, 77°K, 20°K, 4°K). The yellow series of Cu 2O has been studied previously.( 1) In this paper measurements in different parts of the spectrum where the absorption is continuous are reported. The red continuum is situated on the low energy side of the yellow series, the yellow continuum on the high energy side. Both are well described by Elliott's ( 2) theory of indirect and forbidden transitions. The red continuum is probably an indirect transition with phonon creation and annihilation to the first exciton state n = 1. At high temperatures, the yellow series disappears and is replaced by a continuum which is characteristic for a forbidden band to band transition. The “yellow” continuum corresponds to the continuous absorption on the high energy side of the series limit.

Etude spectrophotometrique de la serie jaune de Cu 2O aux basses temperatures

The “yellow” series of absorption lines in Cu 2O crystals has been studied by spectrophotometric methods at different temperatures down to liquid helium. The experimental values of the oscillator strength of the absorption lines have been determinated. The oscillator strength of the first lines ( n = 2) is f 2=2.8×10 −6; the relative oscillator strength f 0(n)= f n f 2 has been calculated from experimental data for different lines. f 0( n) is however determined with a su the very first lines of the series only. Both the value of f 2 and the relative oscillator strength in the series are in good agreement with e lliott's (1) theory of forbidden exciton transitions. These arguments added to others already known (1,2) give a very solid basis to the interpretation of the “yellow” series of Cu 2O as a forbidden exciton spectrum. It has been shown that the maximum of the coefficient of absorption in a line K max decreases with the quantum number n according to a law K max ∝ 1/ n 2 for n ⩾ 3. The lines are of a very assymetric form. A parameter is introduced to characterize this property. The variation of this parameter with n is investigated. The form of the first line ( n = 2) differs very much from the form of the other lines of the series. According to our data, the life time of excitons increases with n ; this result is not inconsistent with T oyozawa's theory. (12)