Browsing by Subject "Silicon substrates"
Now showing 1 - 6 of 6
Results Per Page
Sort Options
Item Open Access Effect of processing options on ultra-low-loss lead-magnesium-niobium titanate thin films for high density capacitors(Elsevier, 2013) Chen W.; McCarthy, K.G.; O'Brien, S.; Çopuroǧlu, Mehmet; Cai, M.; Winfield, R.; Mathewson, A.This work studies the impact of annealing temperatures on PMNT (lead-magnesium niobate-lead titanate, Pb(Mg0.33Nb 0.67)0.65Ti0.35O3) thin films grown on a silicon substrate. The electrical properties of the thin films, such as dielectric constant and loss tangent, are shown to depend strongly on the annealing temperature, with the best electrical properties being achieved at the highest annealing temperature. It is seen that the perovskite phase is highest in the sample annealed at 750 C indicating that a relatively high temperature is necessary for complete transition of PMNT to the perovskite phase. The sample annealed at 400 C exhibits the lowest loss tangent of approximately 0.007 at a frequency of 1 MHz. © 2012 Elsevier B.V.Item Open Access Electrical and chemical characterization of chemically passivated silicon surfaces(IEEE, 2008) Chhabra, B.; Süzer, Şefik; Opila, R. L.; Honsberg, C. B.The surface composition of chemically passivated silicon substrates is investigated using XPS and FTIR techniques. The samples are passivated with methanol, quinhydrone-methanol and iodine-methanol solution after HF treatment. The minority carrier lifetimes of these chemically passivated silicon substrates are also measured. Quinhydrone-methanol solution provides a chemically inert surface and a considerably longer minority carrier lifetime.Item Open Access Flexible metamaterials for wireless strain sensing(American Institute of Physics, 2009-11-04) Melik, R.; Unal, E.; Perkgoz, N. K.; Puttlitz, C.; Demir, Hilmi VolkanWe proposed and demonstrated flexible metamaterial-based wireless strain sensors that include arrays of split ring resonators (SRRs) to telemetrically measure strain. For these metamaterial sensors, we showed that a flexible substrate (e.g., Kapton tape) delivers greater sensitivity and a more linear response as compared to using silicon substrates. Specifically, these tape-based flexible SRR sensors exhibit a significantly improved sensitivity level of 0.292 MHz/kgf with a substantially reduced nonlinearity error of 3% for externally applied mechanical loads up to 250 kgf. These data represent a sixfold increase in sensitivity and a 16-fold reduction in error percentage.Item Open Access Response of polyelectrolyte layers to the SiO2 substrate charging as probed by XPS(2009) Conger, C. P.; Süzer, ŞefikA single layer of the Cationic polyelectrolyte poly(allyamine) hydrochloride (PAH) deposited, using the layer-by-layer technique, on a silicon substrate containing 5 nm oxide layer is investigated by XPS while applying an external potential bias to the sample to control and manipulate the charge built-up on the oxide layer. Under application of a -10 V bias, the oxide layer is positively charged due to Photoemission process, evidenced by the measured Si2p binding energy of 104.4 eV. Application of a +10 V bias attracts the low energy neutralizing electrons, stemming from a hot filament, and leads to a negatively charged oxide layer, also evidenced by the measured Si2p binding energy of 102.9 eV. The single polyelectrolyte overlayer also responds to this polarity change of the oxide layer underneath by displaying a somewhat larger shifts both in the C1s and Nls peaks. In addition to the shifts in the positions, the N1s peaks undergo a significant intensity depletion, mostly on the positively charged -N+ component. We interpret this intensity depletion to be the result of reorientation of some of the dangling positively charged groups by moving toward the negatively charged oxide underlayer. To our knowledge this is the first time that a chemically specific response to an electrical stimuli is reported using XPS. A bilayer LbL film consisting of PAH and PSS, exhibits even a larger charging shift, but this time no intensity alteration is observed, most probably due to locking of the -N+ groups by the -SO3 + counterions of the second layer. © 2009 American Chemical Society.Item Open Access Silicon-Germanium multi-quantum well photodetectors in the near infrared(Optical Society of American (OSA), 2012) Onaran, E.; Onbasli, M. C.; Yesilyurt, A.; Yu, H. Y.; Nayfeh, A. M.; Okyay, Ali KemalSingle crystal Silicon-Germanium multi-quantum well layers were epitaxially grown on silicon substrates. Very high quality films were achieved with high level of control utilizing recently developed MHAH epitaxial technique. MHAH growth technique facilitates the monolithic integration of photonic functionality such as modulators and photodetectors with low-cost silicon VLSI technology. Mesa structured p-i-n photodetectors were fabricated with low reverse leakage currents of ∼10 mA/cm2 and responsivity values exceeding 0.1 A/W. Moreover, the spectral responsivity of fabricated detectors can be tuned by applied voltage. © 2012 Optical Society of America.Item Open Access Synthesis and size differentiation of Ge nanocrystals in amorphous SiO 2(Springer, 2006) Aǧan, S.; Çelik-Aktaş, A.; Zuo, J. M.; Dana, A.; Aydınlı, AtillaGermanosilicate layers were grown on Si substrates by plasma enhanced chemical vapor deposition (PECVD) and annealed at different temperatures ranging from 700-1010 °C for durations of 5 to 60 min. Transmission electron microscopy (TEM) was used to investigate Ge nanocrystal formation in SiO 2:Ge films. High-resolution cross section TEM images, electron energy-loss spectroscopy and energy dispersive X-ray analysis (EDX) data indicate that Ge nanocrystals are present in the amorphous silicon dioxide films. These nanocrystals are formed in two spatially separated layers with average sizes of 15 and 50 nm, respectively. EDX analysis indicates that Ge also diffuses into the Si substrate.