Characterization of Surface and Structure of In Situ Doped Sol‐Gel‐Derived Silicon Carbide. Issue 6 (26th February 2018)

• Record Type: Journal Article
• Authors: Kettner, Olivia; Šimić, Sanja; Kunert, Birgit; Schennach, Robert; Resel, Roland; Grießer, Thomas; Friedel, Bettina
• Other Names: Zschech Ehrenfried guestEditor.
• Is Part Of: Advanced engineering materials. Volume 20:Issue 6(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-02-26
• Subjects: Self‐passivation -- silicon carbide -- sol‐gel processing -- surface termination; Materials -- Periodicals; 620.11
• DOI: 10.1002/adem.201701067
• Languages: English
• ISSNs: 1438-1656

Abstract

Abstract : Silicon carbide (SiC), is an artificial semiconductor used for high‐power transistors and blue LEDs, for its extraordinary properties. SiC will be attractive for more applications, but large‐scale or large‐surface area fabrication, with control over defects and surface is challenging. Sol‐gel based techniques are an affordable alternative toward such requirements. This report describes two types of microcrystalline SiC derived after carbothermal reduction from sol‐gel‐based precursors, one with nitrogen added, the other aluminum. Characterization of their bulk, structure, and surface shows that incorporation of dopants affects the formation of polytypes and surface chemistry. Nitrogen leads exclusively to cubic SiC, exhibiting a native oxide surface. Presence of aluminum instead promotes growth of hexagonal polytypes and induces self‐passivation of the crystallites' surface during growth. This is established by hydrogenation of silicon bonds and formation of a protecting aluminum carbonate species. XPS provides support for the suggested mechanism. This passivation is achieved in only one step, solely by aluminum in the precursor. Hence, it is shown that growth, doping and passivation of SiC can be performed as "one‐pot synthesis". Material without insulating oxide and a limited number of defects is highly valuable for applications involving surface‐sensitive charge‐transfer reactions, therefore the potential of this method is significant. Abstract : Sol‐gel derived silicon carbide is an affordable way toward high‐surface area material for optoelectronics and catalysis. With this method, SiC is grown, doped, and passivated in one step. This work compares N‐ or Al‐doped SiC microcrystals' surface, structure, and bulk character. SiC:Al generates immediately a stable hydrogenated and oxide‐free surface, making this material attractive for applications with surface‐sensitive charge‐transfer processes.