Interfacial Properties of ALD-Deposited Al2O3/p-Type Germanium MOS Structures: Influence of Oxidized Ge Interfacial Layer Dependent on Al2O3 Thickness

Abstract

The influence of interfacial oxidized Ge layer, inadvertently grown during ALD of Al2O3 films, on the interfacial properties of Al2O3/p-Ge MOS structures is studied. Keeping constant the deposition temperature at 300°C, it is shown that the thickness of oxidized Ge layer increases from ∼0.2 to ∼0.5 nm, as Al2O3 thickness increases from 5 to 10 nm, maintaining a composition either of a mixed Ge4+/Ge3+ oxide or a GeAlOx germanate. However, for 25 nm Al2O3 the interfacial layer thickness decreases below 0.1 nm. The density of interface traps shows a strong dependence on the thickness of the interfacial layer regardless of Al2O3 thickness.