Intermediate Cu-O-Si Phase in the Cu-SiO₂/Si(111) System: Growth, Elemental, and Electrical Studies

Abstract

We investigate here the strain-induced growth of Cu at 600 °C and its interactions with a thermally grown, 270 nm-thick SiO2 layer on the Si(111) substrate. Our results show clear evidence of triangular voids and formation of triangular islands on the surface via a void-filling mechanism upon Cu deposition, even on a 270 nm-thick dielectric. Different coordination states, oxidation numbers, and chemical compositions of the Cu-grown film are estimated from the core level X-ray photoelectron spectroscopy (XPS) measurements. We find evidence of different compound phases including an intermediate mixed-state of Cu–O–Si at the interface. Emergence of a mixed Cu–O–Si intermediate state is attributed to the new chemical states of Cu x+, O x , and Si x+ observed in the high-resolution XPS spectra. This intermediate state, which is supposed to be highly catalytic, is found in the sample with a concentration as high as ∼41%. Within the Cu–O–Si phase, the atomic percentages of Cu, O, and Si are ∼1, ∼86, and ∼13%, respectively. The electrical measurements carried out on the sample reveal different resistive channels across the film and an overall n-type semiconducting nature with a sheet resistance of the order of 106 Ω.

Stearic Acid as an Atomic Layer Deposition Inhibitor: Spectroscopic Insights from AFM-IR

“…One possible factor that may have affected these results is the diffusion of copper atoms across the Si/SiO 2 interface, which can alter the monolayer integrity and, thus, contribute to ALD nucleation. However, the diffusion of copper across dielectrics has been shown to have onset temperatures typically higher than 100 • C, which was the temperature of our ALD reactor [56][57][58][59]. Hence, it is unlikely that the diffusion of copper significantly affected our observations.…”

Optimizing the Interfacial Environment of Triphasic ZnO-Cu-ZrO2 Confined inside Mesoporous Silica Spheres for Enhancing CO2 Hydrogenation to Methanol

“…From Figure S9a, it can be observed that the fitted O 1s spectra show Si–O and Cu–O–Zn/Zr bonds on the calcined CZZ-MSS, Si–O and O–Zn/Zr bonds on the calcined ZZ-MSS, and finally Si–O and O–Cu bonds on the calcined C-MSS. After the CO 2 hydrogenation reaction, all of the above-mentioned bonds were shifted to lower binding energies, and the intensities of the Cu–O–Zn/Zr bond in CZZ-MSS, O–Zn/Zr bond in ZZ-MSS, and O–Cu bonds in the calcined C-MSS were decreased and even disappeared (Figure S9b), further implying the presence of robust Cu-ZnO/ZrO 2 interface on the CZZ-MSS catalyst. − High-resolution Si 2p peaks and their fitted peaks are shown in Figure S9c,d. The main peaks at the range of 103.2–104.2 eV correspond to the Si 4+ state in the bulk SiO 2 support. , It was observed that the fitted Si 2p curves of the fresh CZZ-MSS appeared with a small peak at 101.3 eV, which stands for the Si x + species at the interfaces of Si–O–Zn/Zr.…”

Understanding substrate-driven growth mechanism of copper silicide nanoforms and their applications

“…Ordered 2-dimensional (2D) Cu nanostructures on Si(111) have been reported for very low thicknesses by Zang et al [16]. In the recent years, a huge volume of work has been reported on diffusion studies of Cu in Si substrates [17–41]. In most of the studies on the growth of Cu nanostructures on the silicon substrate, the films are deposited at room temperature and post annealed for preparation of nanostructures.…”