Oxidation-induced electron barrier enhancement at interfaces of Ge-based semiconductors (Ge, Ge1xSnx, SiyGe1xySnx) with Al2O3

Experiments on internal photoemission of electrons at interfaces of SiyGe1xySnx binary and ternary alloys (0x0.11; 0y0.19) with amorphous insulating Al2O3 reveal that the application of an additional oxidation step (5min in dry O3 at 300C) after atomic layer deposition of first 1nm of alumina results in a significant increase of the electron barrier height (by 0.40.5eV) as compared to the conventionally grown Al2O3 layers. Furthermore, this supplemental oxidation step facilitates the removal of Ge sub-oxides from the interface. The observed electron barrier enhancement is suggested to be caused by formation of a wide gap germanate interlayer between the Ge-based semiconductors and alumina. Display Omitted Oxidation in O3 at 300C increases electron barrier height at Ge-Al2O3 interfaces.Variation of Sn content in Ge1xSnx up to 12% has no effect on valence band energy.Formation of a germanate interlayer is hypothesized.No composition-sensitive interface dipoles are encountered.