Temperature dependence of the exciton gap in monocrystalline CuGaSe₂

Abstract

Single crystals of CuGaS 2 have been grown by chemical vapour transport. Their near-band gap photoluminescence properties were investigated in the temperature range of 10-300 K. The variation of the exciton gap energy with temperature was studied by means of a three-parameter thermodynamic model, the Einstein model and the Pássler model. Valúes of the band gap at T=0 K, of a dimensionless constant related to the electron-phonon coupling, and of an effective and a cutoff phonon energy have been estimated. It has also been found that the major contribution of phonons to the shift of £ g as a Keywords: function of T in CuGaS 2 is mainly from optical phonons. Chalcopyrite Photoluminescence Spectroscopy 2.42 2.44 2.46 2.48 2.50 2.52 2.54 2.56 Energy (eV)

Temperature dependent band-gap energy for Cu2ZnSnSe4: A spectroscopic ellipsometric study

“…S-containing compounds have higher phonon frequency, thus larger Θ value than the corresponding Se-containing ones, while the dE(T)/dT values for the two compounds are very close [28]. Similar difference has been observed between CuGaSe2 (a = 23 meV) [29] and CuGaS2 (a = 54 -88 meV) [30].…”

Temperature dependence of band gaps in semiconductors: Electron-phonon interaction

“…Figure 11 compiles our new data obtained for CuGaS 2 and compares them with literature data for CuGaSe 2 and CuGaTe 2 . 53,54 The temperature dependence of the exciton energies of all CuGaX 2 chalcopyrites shown in Fig. 11 was initially analyzed by fitting a single Bose-Einstein frequency according to…”

Temperature dependence of the exciton gap in monocrystalline CuGaS2

“…The valué of the exciton gap is determined from luminescence measurements and its variation with temperature is studied using three different models, the three-parameter thermodynamic model of O'Donnell and Chen [13], the Einstein model [14] and the Pássler model [15]. The physical bases of the three models are briefly summarized [16]. For many semiconductors the contribution of the electron-phonon coupling to the temperature variation of the band gap energy is dominant.…”