Epitaxial multi-component rare earth oxide for high-K application

We studied the growth and electrical properties of single crystalline mixed (Nd1 − xGdx)2O3 (NGO) thin films and compared the results with those of the binary Gd2O3 and Nd2O3 thin films, respectively. Epitaxial ternary NGO thin films were grown on Si(100) substrates using modified solid state molecular beam epitaxy. The films were characterized physically using various techniques. The capacitance equivalent oxide thickness of a 4.5 nm NGO thin film extracted from capacitance–voltage (C–V) characteristics was 0.9 nm, which is lower than all values reported earlier for other crystalline oxides. The leakage current density and the density of interface traps were 0.3 mA/cm2 at |Vg − VFB| =  1 V and 1.4 × 1012/cm2, respectively. These excellent electrical properties of NGO thin films demonstrate that such ternary oxides could be one of the promising candidates for gate dielectrics in the upcoming generations of complementary metal oxide semiconductor (CMOS) devices.