Improved interfacial properties of HfGdON gate dielectric Ge MOS capacitor by optimizing Gd content

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 V_g=V_fb + 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 GeO_x at/near the high k/Ge interface by doping suitable Gd into HfON.