Molecular beam epitaxial growth of ZnCdTeO epilayers for intermediate band solar cells

We report the growth and characterization of the lattice-matched Zn _1-xCd_xTe_1yO_y (ZnCdTeO) layers on ZnTe substrates by radio frequency plasma-assisted molecular beam epitaxy technique. The Cd composition increases linearly with increasing Cd/(Zn+Cd) flux ratio, indicating a controllability of Cd composition by Cd flux. Introduction of O radical during the growth of ZnCdTe resulted in the formation of ZnCdTeO layer. At particular O and Cd compositions lattice-matched ZnCdTeO epilayers on ZnTe substrate were obtained. Photoreflectance (PR) spectroscopy on the lattice-matched ZnCdTeO layer revealed two distinct PR features in the energy regions at 2.2-2.5 eV and 1.5-1.8 eV, which can be attributed to transitions from the valence band to the two conduction subbands, E₊ and E-, respectively. © 2013 Elsevier B.V. All rights reserved.