  The structure property of non-ideal Si/GaAs heterostructures that were
integrated with the ultra-thin oxide (UO) tunneling interfacial layer has been
systematically investigated. Si nanomembranes (NMs) were oxidized in different
time periods prior to the hetero-integration process to create the non-ideal
single-side passivated Si/GaAs heterostructure. The atomic level oxygen
distribution and the degree of oxygen content in Si NM and GaAs were carefully
investigated using the atom probe tomography (APT) and X-ray photoelectron
spectroscopy (XPS) to trace the changes in chemical composition and reactional
mechanism across the UO interface when the surface of Si NM was exposed to air
for different period of time. The negatively induced charges at the UO layer
caused the oxygen diffusion to GaAs layer and formed the unwanted GaAs oxide
layer. This native oxide stack noticeably degraded the thermal properties of
the Si/GaAs heterostructure as Si NMs were more oxidized. This study revealed
that the poor surface passivation on the one side of the heterointerface leads
to a both-side oxidation, thus severely deteriorating the transport properties
across the heterojunction that is formed with the UO layer.
