Electrical properties of Ge metal–oxide–semiconductor capacitors with high-k La2O3 gate dielectric incorporated by N or/and Ti**Project supported by the National Natural Science Foundation of China (No. 61274112), the Natural Science Foundation of Hubei Province (No. 2011CDB165), and the Scientific Research Program of Huanggang Normal University (No. 2012028803).

Abstract

LaON, LaTiO and LaTiON films are deposited as gate dielectrics by incorporating N or/and Ti into La2O3 using the sputtering method to fabricate Ge MOS capacitors, and the electrical properties of the devices are carefully examined. LaON/Ge capacitors exhibit the best interface quality, gate leakage property and device reliability, but a smaller k value (14.9). LaTiO/Ge capacitors exhibit a higher k value (22.7), but a deteriorated interface quality, gate leakage property and device reliability. LaTiON/Ge capacitors exhibit the highest k value (24.6), and a relatively better interface quality (3.1 × 1011 eV−1 cm−2), gate leakage property (3.6 × 10−3 A/cm2 at Vg = 1 V + Vfb) and device reliability. Therefore, LaTiON is more suitable for high performance Ge MOS devices as a gate dielectric than LaON and LaTiO materials.