Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 58: Focus Session: Copper oxide semiconductors – An attractive material for photovoltaics?
HL 58.3: Vortrag
Mittwoch, 13. März 2013, 16:00–16:15, H13
Molecular Beam Epitaxy of copper oxides (mainly cuprous oxide Cu2O) — •Max Kracht, Jörg Schörmann, Thomas Sander, Peter J. Klar, and Martin Eickhoff — I. Physikalisches Institut, Justus-Liebig-Universität Gießen, Germany
Semiconducting binary oxides (SBOs) are currently gaining intense research interest. Within this class of materials the copper oxide system (Cu-O) with the two stable phases cubic Cu2O (cuprous oxide) and monoclinic CuO (cupric oxide) presents a fascinating exception both in terms of its electronic and its optical properties. The different Cu-O phases possess optical band gaps in the visible part of the spectrum (Eg(Cu2O)=2.1 eV, Eg(CuO)=1.4 eV at RT) which makes them suitable for application as absorber layers in photovoltaic devices. Cu-O thin films were grown by plasma assisted molecular beam epitaxy (PAMBE) on MgO substrates. An increase of flux ratio of Cu/O leads to a phase transition from CuO to Cu2O which means that the phase can be controlled by the adjustment of stochiometrie of the deposited layer. Phase pure Cu2O films were achieved at a substrate temperature of 700 ∘C, as demonstrated by high resolution x-ray diffraction and Raman spectroscopy. For the growth of Cu2O (001) on MgO (001) substrates the appearance of (011) misorientations, i.e. the growth rate on the different facets, has been found to be sensitively controllable and supressed by the Cu/O ratio during PAMBE growth. Hall-Effect measurements reveal a p-type carrier concentration of 6.1·1015 cm−3 and a mobility of 47.2 cm2/Vs for Cu2O films.