Epitaxial electrodeposition of Cu2O films onto InP(001)

Cu 2 O (cuprite) films were deposited electrochemically onto InP (001) single-crystal substrates from aqueous solutions at room temperature. X-ray diffraction indicates a unique epitaxial 45°[001] orientation relationship between Cu2O and InP. This reduces the mismatch between corresponding spacings to 2.9%, compared with a mismatch of 27.2% between the lattice parameters of Cu2O and InP. The morphology of the Cu2O film can be influenced via the electrolyte acidity. At a pH of 9.0, Cu2O forms pyramidal islands. At a pH of 12.0, on the other hand, cubelike morphologies of Cu2O are observed. Between a pH of 9.0 and 12.0, the direction of slowest growth changes from 〈111〉 to 〈100〉. In apparent contradiction to the observation of a unique epitaxial orientation relationship, transmission electron microscopy reveals an amorphous oxygen-rich interlayer between the Cu2O and the InP crystal.