Heteroepitaxial growth of layered semiconductors, LaZnOPn (Pn = P and As)

LaZnOPn (Pn=P and As) thin films were successfully grown on MgO (001) substrates with an epitaxial relationship of (001) LaZnOPn 11 (001) MgO and [110] LaZnOPn 11 [110] MgO. The electrical conductivity of undoped LaZnOP epitaxial film was so low, 3.1 x 10(-6) S/cm at room temperature, that reliable Seebeck and Hall measurement results were not obtained. On the other hand, the electrical conductivities of the Cu-doped LaZnOP and undoped LaZnOAs epitaxial films were 2.7 x 10(-2) and 2.0 x 10(-1) S/cm at room temperature, respectively. The Seebeck coefficients of both the epitaxial films were positive, indicating p-type semiconductors. The optical bandgaps of LaZnOP and LaZnOAs were estimated to be similar to 1.7 eV and similar to 1.5 eV, respectively. (C) 2007 Elsevier B.V. All rights reserved.