ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Hydrogen etching of 4H-SiC has been performed in a hot-wall chemical vapor depositionreactor to reduce surface damage and to create a bilayer-stepped surface morphology, optimal forinitiation of growth on 4H-SiC substrates offcut 4° and 8° towards the 〈11-20〉 direction. Tounderstand how step bunching evolves during the ramp to growth temperature, samples were etchedending at temperatures from 1400 to 1580°C under 0, 2 or 10 sccm of propane (C3H8) addition tohydrogen. Initial exploratory growth of 5 μm thick epilayers on the 4° etched surfaces are alsodiscussed. Atomic force microscopy (AFM) and Nomarski microscopy were employed toinvestigate changes in the surface morphology. The 8° substrates subjected to H2-C3H8 etching upto growth temperature routinely exhibited bilayer steps. However, when the 4° substrates wereetched with a 10 sccm C3H8 flow, considerable step bunching was observed. At 1450°C, with a10 sccm of C3H8 flow (partial pressure is 1.25x10-5 bar), step bunching started with the formation ofribbon-like steps. Progression to higher temperature etches have shown the coalescence of theribbons into larger macro-steps up to 30 nm in height. Etching 4° substrates under 2 sccm of C3H8(partial pressure is 2.5x10-6 bar) or in pure H2 up to 1500°C results in minimal step bunching
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/17/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.556-557.513.pdf
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