Growth and characterization of highly mismatched Zn1?xCdxTe1?yOy alloys for intermediate band solar cells

We report the growth and characterization of the Zn_1-xCd_xTe_1-yO_y (ZnCdTeO) layers on ZnTe substrates by molecular beam epitaxy technique for the application of intermediate band solar cells. ZnCdTeO layers with a wide range of Cd and O contents of 0-0.7 and 0.005-0.02, respectively, were grown by changing Cd/(Cd+Zn) flux ratio and O radical supply. The decrease of the transition energy from valence band (VB) to E- band with increasing Cd content was observed by photoreflectance measurements and the variation was consistent with the theoretical calculations based on the band anticrossing model. The magnitude of the optical absorption near the transition energy from VB to E- band depended on the Cd content because of the change of the E- band character.