New method to study band offsets applied to strainedSi/Si1−xGex(100)heterojunction interfaces

A new method based on x-ray photoelectron spectroscopy measurements in combination with ion-beam doping during molecular-beam-epitaxy growth has been developed to study band offsets for $\mathrm{Si}/{\mathrm{Si}}_{1-x}{\mathrm{Ge}}_x\mathrm{}\left(100\right)\mathrm{}$ heterostructures. Both $\Delta E_c$ and $\Delta E_v$ have been determined experimentally at abrupt heterojunction interfaces with a Si layer thickness of ∼35 Å on a ${\mathrm{Si}}_{1-x}{\mathrm{Ge}}_x$ alloy layer. Significant differences in band lineup have been observed for heterostructures grown on different buffer layers, which are consistent with previous theoretical calculations of strain effects.