Heterojunction band discontinuity at the Si–Ge(111) interface Available to Purchase

The interface formed when Si is evaporated on clean cleaved Ge(111) is studied using photoemission spectroscopy, Auger electron spectroscopy (AES), and low energy electron diffraction (LEED) at growth temperatures of 20 and 300 °C to investigate the effect of the change in morphology at the interface between disordered and pseudomorphic growth. The interface is most likely abrupt at room temperature while intermixing of Ge is observed for the high temperature growth. From LEED and other considerations, the atomic structure at the interface is changed, but no measurable difference between the Si core level energy compared to the Ge core level energy is found for the two growth temperatures. This is interpreted as the absence of heterojunction band discontinuity change [neglecting possible strain effects on the valence band maximum]. This indicates further the absence of a modification of the band lineups due to slightly ionic bonds crossing the interface, which is called the atomic bonding dipole. The valence bands were also observed directly for the 300 °C growth with 130 eV photons and the heterojunction discontinuity was 0.4±0.1 eV.