Controlling the surface roughness of epitaxial SiC on silicon

Abstract

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A catalytic alloy approach for graphene on epitaxial SiC on silicon wafers

“…This endeavor has proved more challenging than expected, in particular, because of the upper limit set by the melting temperature of silicon and the scarce availability of a defect-free and atomically smooth epitaxial SiC on Si(111) starting template. 8,9 In response to such challenges, we have recently demonstrated an alternate approach to the wafer-level, transfer-free uniform synthesis of graphene on silicon. 10 As for the sublimation process, our new methodology relies on the use of epitaxial SiC on silicon as a solid source of carbon.…”

Factors affecting the f × Q product of 3C-SiC microstrings: What is the upper limit for sensitivity?

“…In addition, we measured the SiC films root-mean-square (RMS) roughness to be $3 nm using Park NX20 atomic force microscopy (AFM) in non-contact mode. 66 We fabricated a range of epitaxial 3C-SiC microstrings deposited on on-axis Si(100) and Si(111) with lengths of up to 2600 lm, thicknesses of 50 nm and 255 nm, and widths of 4-12 lm through the four stages of photolithography, SiC anisotropic etching using hydrogen chloride (HCl), Si isotropic etching using xenon difluoride (XeF 2 ), and photoresist removal through TEGAL 915 oxygen plasma. We applied two lithography stages, as explained in our previous work, 29 in order to ensure that the strings are perfectly clamped.…”

“…In addition, the Q factor decreases by almost an order of magnitude (from 2.4 Â 10 6 to 2.6 Â 10 5 ) as the thickness reduces from 255 nm to 50 nm for the SiC(111) strings with the same l-w geometries. The reduction can be linked to the decrease of the mean stress from 650 MPa to 230 MPa and also the fact that the defect density 66 is very high for 50 nm thickness, as the initial few nanometers of heteroepitaxial growth is the most defective part of the film. This results in high energy dissipation in the 50 nm thick strings and so a substantially lower Q.…”

Quantum optomechanics in the unresolved sideband regime

“…Despite that, the formation of defects such as misfit dislocation and stacking faults within the SiC crystal is inevitable due to the differing thermal expansion coefficients (∼ 8% during the cool down) and lattice constants (∼ 20%) of Si and 3C-SiC [322,[335][336][337].…”

“…Firstly, the mean stress drops from 650 MPa to 230 MPa. Secondly, the 50 nm thick devices are comprised of the defect-heavy portion of the 3C-SiC film nearest to the SiC-Si interface [336]. This results in high internal friction that substantially lowers the Q.…”