Structure and optoelectronic properties of Si/O superlattice

We have carried out structural study of the Si/O semiconductor atomic superlattices (SAS) with up to 18 Si/O layers fabricated by molecular beam epitaxy and in situ oxygen exposure on both Sb-doped and undoped Si buffer layers, and correlated the results with our photoluminescence, electroluminescence (EL) and I–V data. The Si/O SAS is a new type of superlattice, where monolayers of oxygen are sandwiched between the Si layers. High-resolution cross-sectional transmission electron microscopy (TEM) study has confirmed the presence of the superlattice and shown epitaxy in the Si/O superlattices. The high structural quality of the layers grown on the undoped Si buffer layers with low density of stacking faults—less than 107/cm2—was established by TEM. Although structure perfection is very important allowing this new class of superlattices to be extended to other systems, it is important to point out that a 9-period SAS-based EL device with emission of light in green has been life-tested with stable output for over 1 year of continuous operation. The Si/O superlattice also serves as an epitaxially grown insulating layer as possible replacement of silicon-on-insulator. Together with the tailor-made effective band gap, this epitaxially grown superlattice may serve as future silicon-based three-dimensional integrated circuits.