Impacts of Ti on electrical properties of Ge metal–oxide–semiconductor capacitors with ultrathin high-k LaTiON gate dielectric

摘要

Ge Metal–Oxide–Semiconductor (MOS) capacitors with LaON gate dielectric incorporating different Ti contents are fabricated and their electrical properties are measured and compared. It is found that Ti incorporation can increase the dielectric permittivity, and the higher the Ti content, the larger is the permittivity. However, the interfacial and gate-leakage properties become poorer as the Ti content increases. Therefore, optimization of Ti content is important in order to obtain a good trade-off among the electrical properties of the device. For the studied range of the Ti/La₂O₃ ratio, a suitable Ti/La₂O₃ ratio of 14.7% results in a high relative permittivity of 24.6, low interface-state density of 3.1×1011 eV−1 cm−2, and relatively low gate-leakage current density of 2.0×10−3 A cm−2 at a gate voltage of 1 V.