Strain relaxation is studied in strained silicon directly on insulator (SSDOI) substrates patterned with nanoscale features. Using interference lithography, biaxially strained SSDOI substrates with 30nm thick strained Si on insulator films were patterned into grating structures with 90nm wide stripes, and arrays of 80nm×170nm pillars. The strain profiles of these patterned structures were examined by ultraviolet Raman spectroscopy. Raman analysis of the SSDOI gratings indicates strain relaxation in the 90nm wide stripes, compared to the strain measured in unpatterned portions of the SSDOI wafer. Three-dimensional finite-element modeling of the stress distributions in the grading structures predicts that 95% of the strain is maintained in the direction along the length of the stripes. These simulations are used to decouple the strain components along the width and length of the SSDOI grating structure, inferred from Raman measurements. The results are consistent with substantial stress relaxation across the width of the stripes and very little stress relaxation along the length of the stripes.
The desorption energies, DE against the polarizabilities, a, of the alkanes also reveals that DE cannot arise from the scaling of the polarizability with chain length. We discuss other possible origins of DE including lattice commensurability effects, temperature, and desorption order.
The continued reduction in the head-disk separation of magnetic data storage systems and the corresponding increase in the frequency of head-disk contacts will place severe stress on the lubricant and overcoat used to protect the surfaces of magnetic media. With decreasing fly heights, environmental conditions such as temperature and humidity that influence the lubricant-overcoat interactions become increasingly important to the tribological performance of the head-disk interface. It is essential to obtain a fundamental understanding of the molecular interactions at the lubricant-overcoat interface in order to maintain the reliability of future hard disk drives. The coadsorption of model fluoro alcohols and fluoro ethers with water was studied to gain a fundamental understanding of the effects of humidity on the bonding of perfluoropolyalkyl ether (PFPE) lubricants to amorphous hydrogenated carbon (a-CHx) overcoats. Temperature-programmed desorption experiments were performed using 2,2,2-trifluoroethanol (CF3CH2-OH) coadsorbed with water and perfluorodiethyl ether [(CF3CF2)2O] coadsorbed with water. The results indicate that the presence of water increases the desorption energy of CF3CH2OH on the a-CHx overcoat but decreases the desorption energy of (CF3CF2)2O on a-CHx overcoats. The implication of these results is that there is a net increase in the mobility of PFPE lubricant films when exposed to humid environments.
Increasing operating temperatures within hard disk drives promote increased outgassing from drive components and thus can adversely influence the durability and reliability of hard disk drives. This study investigates the effects of hydrocarbon contamination on the bonding of perfluoropolyalkyl ether (PFPE) lubricants to amorphous hydrogenated carbon (a-CHx) overcoats. This work has used decane (C10H22) as a model for the hydrocarbon contamination present in drives and perfluorodiethyl ether ((CF3CF2)2O) and 2,2,2-trifluoroethanol (CF3CH2OH) as models for the backbone and endgroups, respectively, of the common disk lubricant Fomblin Zdol. Temperature-programmed desorption experiments were conducted using CF3CH2OH coadsorbed with C10H22 on an a-CHx overcoat and (CF3CF2)2O coadsorbed with C10H22 on an a-CHx overcoat. The results indicate that the presence of C10H22 decreases the adsorption energies of both CF3CH2OH and (CF3CF2)2O on the a-CHx overcoats. The implication of these results is that the mobility of PFPE lubricant films can be increased by the presence of hydrocarbon contaminants on the disk surface.
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