Evolution of interface chemistry and dielectric properties of HfO2/Ge gate stack modulated by Gd incorporation and thermal annealing

In current work, effects of rapid thermal annealing (RTA) on the interface chemistry and electrical properties of Gd-doped HfO2 (HGO)/Ge stack have been investigated systematically. It has been demonstrated that the presence of GeOx interfacial layer between HfGdO and Ge is unavoidable and appropriate annealing can improve metal-oxide-semiconductor device characteristics such as interface state density, accumulation capacitance, frequency dispersion, and leakage current. The involved leakage current conduction mechanisms for metal-oxide-semiconductor (MOS) capacitors based on sputtered HGO/Ge gate stacks with optimal annealed temperature also have been discussed in detail. As a result, the Al/HGO barrier height and the band offset of HGO/Ge gate stack have been determined precisely.