Applications of Cubic MgZnO Thin Films in Metal-Insulator-Silicon Structures

Cubic Mg_0.55Zn_0.45O thin film alloys have been deposited on Si substrates at low growth temperature. The topography of the cross section of the epitaxial film by scanning electronic microscope demonstrates good morphology and high interfacial quality. The high (001) orientation and wide band-gap (E_g > 5.5 eV) of the cubic Mg_0.55Zn_0.45O thin films accord with the guidelines for metal-insulator-silicon (MIS) device applications. Using the cubic ternary thin films as insulators, MIS structures have been fabricated. The capacitance-voltage measurements show the flat band voltage shift V_FB of 11.8 V and mobile ion density D_mc of 5.57 x 10¹⁰cm^-2 for the MIS structure. Leakage current density as low as ～ 10^-7 A/cm² is obtained at E = 700 kV/cm by the current-voltage measurements. These unique structural and electrical properties of the fabricated MIS devices indicate that cubic MgZnO materials could become a new candidate for high-k dielectrics used in silicon integrated circuit technologies.