Fabrication of high-performance Ge-MOS structure using Al2O3/TiO2stacked gate insulating film

In recent years, combination of high-µ materials and high-k insulating films has attracted attention as a technique for future switching devices. Using a Ge substrate as a high-µ material, it is expected that the operation speed of the device will be increased. On the other hand, it is necessary to introduce a high-k material. However, it is difficult to obtain good interface characteristics by direct deposition of HfO
2
or Al
2
O
3
on Ge substrates. In this study, we tried to introduce another high dielectric constant material TiO
2
. Additionally, we have considered a stacked structure with Al
2
O
3
, which has a large band gap (8.8 [eV]). In this study, high performance Ge-MOS was realized with Al
2
O
3
/TiO
2
/Ge structure.