The continued scaling of CMOS transistor requires replacement of the conventional silica gate oxide (SiO2) with a higher dielectric constant (K) gate dielectric to minimize the leakage current and to maintain a high capacitance especially at nano level to escape Quantum Mechanical Tunneling. Among many contenders, La2O3 is believed to be the suitable successor but the lanthanide oxides are known to be hygroscopic, which can affect their dielectric quality. Hence, we present a work on mixing the lanthanum oxide (or lanthana) with a less hygroscopic oxide such as Al2O3 to stabilize the insulator layer. Lanthanum Aluminate (LaAlO3) is much less susceptible to moisture. It also combines the advantages of the high dielectric constant of La2O3 and the chemical and thermal stability of Al2O3. Synthesis of Lanthanum Aluminate nano particles is done by Gelation-Precipitation method and are characterized by XRD, PSA, UV-Vis, TG/DTA, SEM, TEM and LCR-meter. The SiO2, La2O3, LaAlO3 are simulated, the reduction in leakage current of MOSFET using nano Silica, nano Lanthana and nano Lanthanum Aluminate insulator is studied using Quantum Wise-Virtual Nano Lab and Nextnano software tools.