Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 16: II-VI Semiconductors I
HL 16.4: Vortrag
Montag, 26. März 2012, 15:45–16:00, EW 202
Optical characterization of CdSe/ZnTe type-II interfaces for photovoltaics — •Jan-Peter Richters1, Lionel Gerard2, Regis Andre2, and Joel Bleuse1 — 1CEA-CNRS group "Nanophysique et semiconducteurs", CEA-Grenoble, INAC, SP2M, 17 rue des Martyrs, 38042 Grenoble, France — 2CEA-CNRS group "Nanophysique et semiconducteurs", Institut Néel, CNRS, BP 166, 38042 Grenoble Cedex 9, France
Solar cells based on direct bandgap semiconductors (GaAs, CdTe, CdSe...) show an efficient light absorption compared to silicon solar cells. This is an advantage for material savings due to thinner absorbers, but it also comes with the drawback of higher losses due to efficient radiative electron-hole recombination. Such losses could be prevented through the use of type-II interfaces which separate electrons and holes within the active area, similar to a p-n junction. We report a study of CdSe/ZnTe samples showing such an interface. The CdSe bandgap (1.7 eV) is well adapted to the solar spectrum and its lattice parameter mismatch with ZnTe is exceptionally low. We have grown, by MBE, different kinds of samples like CdSe/ZnTe 2D interfaces and superlattices and present time-resolved spectroscopy results which specify the efficiency of the electron-hole separation in these type-II structures. The measured decay time can be above 100 ns for the interface optical transition, i.e. 3 orders of magnitude slower than the typical PL decay time for the constitutive materials taken separately.