Elsevier, Solar Energy Materials and Solar Cells, (133), p. 82-86
DOI: 10.1016/j.solmat.2014.10.048
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High quality epitaxial crystalline Cu(In,Ga)Se2 (CIGS) films were grown on n-type (1 0 0)—Germanium (Ge) substrates using pulsed electron deposition (PED) technique at a remarkably low substrate temperature of 300 °C, thanks to the high-energy of adatoms arriving to the substrate. The crystalline quality was confirmed by X-ray diffraction techniques and from Transmission Electron Microscopy and the only defects found were twin boundaries along the (1 1 2) direction in these CIGS films; surprisingly neither misfit dislocations nor Kinkerdall voids were observed. A 100 meV optical band located below the band edge was observed by Photoluminescence technique. Current–voltage and capacitance–voltage measurements confirm an intrinsic p-type conductivity of CIGS films, with a free carrier concentration of ≈3.5×1016 cm−3. These characteristics of crystalline CIGS films are crucial for a variety of potential applications, such as more efficient absorber layers in single-junction and as an integral component of multi-junction thin-film solar cells.