Improvements on the Interfacial Properties of High-k/Ge MIS Structures by Inserting a La2O3 Passivation Layer

Abstract

In this paper, the impact of La2O3 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 LaGeOx component by incorporating a La2O3 interlayer could effectively suppress desorption of the interfacial layer from GeO2 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 Al2O3/La2O3/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 La2O3 passivation layer.