Improvements on the Interfacial Properties of High-k/Ge MIS Structures by Inserting a La(2)O(3) Passivation Layer

In this paper, the impact of La(2)O(3) passivation layers on the interfacial properties of Ge-based metal-insulator-semiconductor (MIS) structures was investigated. It was proven that the formation of a thermodynamically stable LaGeO(x) component by incorporating a La(2)O(3) interlayer could effectively suppress desorption of the interfacial layer from GeO(2) to volatile GeO. The suppression of GeO desorption contributed to the decrease in oxide trapped charges and interfacial traps in the bulk of the gate insulator, or the nearby interfacial regions in the Al(2)O(3)/La(2)O(3)/Ge structure. Consequently, the hysteretic behavior of the dual-swept capacitance-voltage (C-V) curves and the frequency dispersion of multi-frequency C-V curves were remarkably weakened. Besides, more than one order of magnitude decrease in the gate leakage current density, and higher insulator breakdown electric field were obtained after inserting a La(2)O(3) passivation layer.