| Abstract
| - For a variety of surface and growth conditions, strong interaction of the SrTiO3(001) substrate with the first few monolayers of Cu(I)-oxide quantum dots (OQDs) leads to the formation of Cu(II) at the interface. However, the impact of this interaction weakens with increasing thickness of OQDs and/or modification of the substrate surface, resulting in exclusive formation of Cu(I).
- Copper(I) oxide quantum dots (OQDs) were grown in various thicknesses on differentSrTiO3(001) surfaces and were investigated by near-edge X-ray absorption fine structure(NEXAFS) spectroscopy. The experimental growth conditions for the OQDs were optimizedto obtain Cu2O as the major phase. The OQDs grown on clean SrTiO3(001) surfaces at 825K and higher with p(O2) of 9.0 × 10-7 Torr or greater contain mostly CuO, contrasting toOQDs grown at 800 K with p(O2) of ∼7.0 × 10-7 Torr that contain primarily Cu2O.Furthermore, there is a strong interaction between the SrTiO3(001) surface and the firstfew monolayers of the OQDs, which induces the formation of Cu(II). However, this interactionis mitigated with increasing thickness of OQDs, resulting in the exclusive formation of Cu2Oin the topmost layers. The influence of the SrTiO3(001) substrate on the formation of OQDscan be minimized by modifying the substrate surface using chemical treatment and/orenergetic Au2+ ion-beam irradiation. Examination of the photochemical properties of theseOQDs shows that prolonged soft X-ray irradiation under vacuum reduces Cu(II), which ispresent as a minor impurity in the Cu(I) OQDs.
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