Oxidation-induced electron barrier enhancement at interfaces of Ge-based semiconductors (Ge, Ge1−xSnx, SiyGe1−x−ySnx) with Al2O3

Abstract

Experiments on internal photoemission of electrons at interfaces of SiyGe1-x-ySnx binary and ternary alloys (0<x<0.11; 0<y<0.19) with amorphous insulating Al2O3 reveal that the application of an additional oxidation step (5 min in dry O3 at 300 °C) after atomic layer deposition of first ≈1 nm of alumina results in a significant increase of the electron barrier height (by ≈0.4-0.5 eV) 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.

Electrical properties of extended defects in strain relaxed GeSn

“…For obtaining the band-diagram, it is sufficient to use basic mobility models and the definition of bandgap. Since there is no measurable shift in the position of the valence band at the Ge/GeSn interface, 26 an electron affinity (v ¼ E g À E V ) of 4.1 eV is used for the Ge 0.922 Sn 0.078 layer (at k ¼ À0:5%). The defect-states in Ge are not studied in this work, due to higher n-type doping and therefore are only shown for the illustration purpose in Fig.…”