Excited states of the free excitons in CuInSe2 single crystals

Applied Physics Letters

et al. 2011

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Cu2ZnSnSe4 thin films, fabricated on bare or molybdenum coated glass substrates by magnetron sputtering and selenisation, were studied by a range of techniques. Photoluminescence spectra reveal an excitonic peak and two phonon replicas of a donor-acceptor pair (DAP) recombination. Its acceptor and donor ionisation energies are 27 and 7 meV, respectively. This demonstrates that high-quality Cu2ZnSnSe4 thin films can be fabricated. An experimental value for the longitudinal optical phonon energy of 28 meV was estimated. The band gap energy of 1.01 eV at room temperature was determined using optical absorption spectra

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confidence: 99%

“…The most efficient technique for gaining such knowledge is optical spectroscopy [3][4][5]. However, the usefulness of such methods depends critically on the availability of high quality material, with sharp and resolved features in the optical spectra.…”

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confidence: 99%

Optical properties of high quality Cu2ZnSnSe4 thin films

Luckert

Hamilton

Applied Physics Letters

et al. 2011

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“…18 The determined C exciton ground state (l ¼ 0) binding energy at zero field E b (C) ¼ Ry so *(0,0) ¼ 8.5 meV is very close to E b for A and B of 8.5 and 8.4 meV, respectively. 8 Subtracting 8.5 meV from E g (C) the spectral position of the C exciton can be calculated as 1.2743 eV which is close to the experimentally observed value of 1.2750 eV in the zero field absorption spectrum in Fig. 1.…”

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confidence: 61%

“…Early optical spectroscopy studies of the excitonic properties of CuInSe 2 revealed the complexity of the valence band, which is split into A, B, and C sub-bands by the simultaneous influence of the non-cubic crystal field and spin-orbit coupling. 5 Recently, the excitonic studies were extended by works based on new advances in the material structural quality [6][7][8][9] determining accurate values of the A and B exciton binding energies E b 7 and hole effective masses. 9 Significantly fewer papers however are concerned with the C exciton, although the C-band parameters are necessary for the development of kp theory in the chalcopyrites.…”

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confidence: 99%

Landau levels of the C-exciton in CuInSe2 studied by magneto-transmission

Applied Physics Letters

Rodina

Shuchalin

et al. 2014

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The electronic structure of the solar cell absorber CuInSe2 is studied using magneto-transmission in thin polycrystalline films at magnetic fields up to 29 T. A, B, and C free excitons are resolved in absorption spectra at zero field and a Landau level fan generated by diamagnetic exciton recombination is observed for fields above 7 T. The dependence of the C band exciton binding energy on magnetic fields, calculated using a hydrogenic approximation, is used to determine the C exciton Rydberg at 0 T (8.5 meV), band gap (1.2828 eV), and hole effective mass mso = (0.31 ± 0.12)m0 for the C valence sub-band.

“…These values are close to E a1 , the thermal depth of w1, suggesting than the hole in the w1 exciton can be associated with either A or B sub-band. Both E a1 and E a2 are significantly greater than the binding energies of the A and B free excitons of 8.5 and 8.4 meV, 33,34 respectively, indicating that the w1 exciton is formed not by the capture of free excitons but by the capture of separate charge carriers. The two activation energies can be related to the localisation energies of the captured electron and hole.…”

Section: Temperature Dependence Of the W-linesmentioning

confidence: 99%

A photoluminescence study of excitonic grade CuInSe2 single crystals irradiated with 6 MeV electrons

Journal of Applied Physics

Mudryi

Borodavchenko

et al. 2015

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This version is available at https://strathprints.strath.ac.uk/54688/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the High-quality single crystals of CuInSe 2 with near-stoichiometric elemental compositions were irradiated with 6 MeV electrons, at doses from 10 15 to 3 Â 10 18 cm À2 , and studied using photoluminescence (PL) at temperatures from 4.2 to 300 K. Before irradiation, the photoluminescence spectra reveal a number of sharp and well resolved lines associated with free-and bound-excitons. The spectra also show broader bands relating to free-to-bound transitions and their phonon replicas in the lower energy region below 1.0 eV. The irradiation with 6 MeV electrons reduces the intensity of the free-and the majority of the bound-exciton peaks. Such a reduction can be seen for doses above 10 16 cm À2 . The irradiation induces new PL lines at 1.0215 eV and 0.9909 eV and also enhances the intensity of the lines at 1.0325 and 1.0102 eV present in the photoluminescence spectra before the irradiation. Two broad bands at 0.902 and 0.972 eV, respectively, are tentatively associated with two acceptor-type defects: namely, interstitial selenium (Se i ) and copper on indium site (Cu In ). After irradiation, these become more intense suggesting an increase in the concentration of these defects due to irradiation. V C 2015 AIP Publishing LLC.[http://dx