Surface-Energy-Anisotropy-Induced Orientation Effects on RayleighInstabilities in Sapphire
Arrays of controlled-geometry, semi-infinite pore channels of systematically varied crystallographic orientation were introduced into undoped m-plane (10{bar 1}0) sapphire substrates using microfabrication techniques and ion-beam etching and subsequently internalized by solid-state diffusion bonding. A series of anneals at 1700 C caused the breakup of these channels into discrete pores via Rayleigh instabilities. In all cases, channels broke up with a characteristic wavelength larger than that expected for a material with isotropic surface energy, reflecting stabilization effects due to surface-energy anisotropy. The breakup wavelength and the time required for complete breakup varied significantly with channel orientation. For most orientations, the instability wavelength for channels of radius R was in the range of 13.2R-25R, and complete breakup occurred within 2-10 h. To first order, the anneal times for complete breakup scale with the square of the breakup wavelength. Channels oriented along a <11{bar 2}0> direction had a wavelength of {approx} 139R, and required 468 h for complete breakup. Cross-sectional analysis of channels oriented along a <11{bar 2}0> direction showed the channel to be completely bounded by stable c(0001), r{l_brace}{bar 1}012{r_brace}, and s{l_brace}10{bar 1}1{r_brace} facets.
- Research Organization:
- Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
- Sponsoring Organization:
- USDOE Director. Office of Science. Office of Basic EnergySciences. Materials Sciences and Engineering Division; National ScienceFoundation graduate Fellowship; Eugene Cota-Robles Fellowship
- DOE Contract Number:
- AC02-05CH11231
- OSTI ID:
- 891211
- Report Number(s):
- LBNL--58793; BnR: KC0201020
- Journal Information:
- Surface Science, Journal Name: Surface Science Journal Issue: 4 Vol. 600; ISSN SUSCAS; ISSN 0039-6028
- Country of Publication:
- United States
- Language:
- English
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