High-$\kappa$ $\hbox{Al}_{2}\hbox{O}_{3}{-}\hbox{HfTiO}$ Nanolaminates With Less Than 0.8-nm Equivalent Oxide Thickness

High quality nanolaminate stacks consisting of five Al
₂
O
₃
-HfTiO layers with an effective dielectric constant of about 22.5 are reported. A dielectric constant for binary HfTiO thick films of about 83 was also demonstrated. The electrical characteristics of as-deposited structures and ones which were annealed in an O
₂
atmosphere at up to 950 degC for 5-10 min were investigated. Two types of gate electrodes: Pt and Ti were compared. The dielectric stack which was annealed up to 500 degC exhibits a leakage current density as small as ~1times10
^-4
A/cm
²
at an electric of field 1.5 MV/cm for a quantum-mechanical corrected equivalent oxide thickness of ~0.76 nm. These values change to ~1times10
^-8
A/cm
²
and 1.82 nm, respectively, after annealing at 950 degC