Improved interfacial properties of HfGdON gate dielectric Ge MOS capacitor by optimizing Gd content**Project supported by the National Key Research and Development Program of China (Grant No. 2018YFB2200500) and the National Natural Science Foundation of China (Grant Nos. 61851406 and 61274112).

Abstract

High-quality dielectric/Ge interface and low gate leakage current are crucial issues for high-performance nanoscaled Ge-based complementary metal–oxide–semiconductor (CMOS) device. In this paper, the interfacial and electrical properties of high-k HfGdON/LaTaON stacked gate dielectric Ge metal–oxide–semiconductor (MOS) capacitors with different gadolinium (Gd) contents are investigated. Experimental results show that when the controlling Gd content is a suitable value (e.g., ∼ 13.16%), excellent device performances can be achieved: low interface-state density (6.93 × 1011 cm−2 · eV−1), small flatband voltage (0.25 V), good capacitance–voltage behavior, small frequency dispersion, and low gate leakage current (2.29× 10−6 A/cm2 at Vg = Vfb + 1 V). These could be attributed to the repair of oxygen vacancies, the increase of conduction band offset, and the suppression of germanate and suboxide GeOx at/near the high k/Ge interface by doping suitable Gd into HfON.