Mario Curiel

Disinfection of titanium dioxide nanotubes using super-oxidized water decrease bacterial viability without disrupting osteoblast behavior.

Amorphous titanium dioxide (TiO2) nanotubes (NTs) on Ti6Al4V alloy were synthesized by anodization using a commercially available super-oxidized water (SOW). The NT surfaces were sterilized by ultraviolet (UV) irradiation and disinfected using SOW. The adhesion and cellular morphology of pig periosteal osteoblast (PPO) cells and the behavior of Staphylococcus aureus (S. aureus) cultured on the sterilized and disinfected surfaces were investigated. A non-anodized Ti6Al4V disc sterilized by UV irradiation (without SOW) was used as control. The results of this study reveal that the adhesion, morphology and filopodia development of PPO cells in NTs are dramatically improved, suggesting that SOW cleaning may not disrupt the benefits obtained by NTs. Significantly decreased bacterial viability in NTs after cleaning with SOW and comparing with non-cleaned NTs was seen. The results suggest that UV and SOW could be a recommendable method for implant sterilization and disinfection without altering osteoblast behavior while decreasing bacterial viability.

Application of Metal-Oxide-Semiconductor structures containing silicon nanocrystals in radiation dosimetry

Abstract This article makes a brief review of the most important results obtained by the authors and their collaborators during the last four years in the field of the development of metal-insulator-silicon structures with dielectric film containing silicon nanocrystals, which are suitable for applications in radiation dosimetry. The preparation of SiOx films is briefly discussed and the annealing conditions used for the growth of silicon nanocrystals are presented. A two-step annealing process for preparation of metal-oxide-semiconductor structures with three-layer gate dielectrics is described. Electron Microscopy investigations prove the Si nanocrystals growth, reveal the crystal spatial distribution in the gate dielectric and provide evidences for the formation of a top SiO2 layerwhen applying the two-step annealing. Two types of MOS structures with three region gate dielectricswere fabricated and characterized by high frequency capacitance/conductancevoltage (C/G-V) measurements. The effect of gamma and ultraviolet radiation on the flatband voltage of preliminary charged metal-oxide-semiconductor structures is investigated and discussed.

Formation of Si Nanocrystals in Thin SiO2 Films for Memory Device Applications

X-ray Diffraction and Reflectivity, Transmission Electron Microscopy and Atomic Force Microscopy were applied to study the effect of thermal annealing on the properties of thin SiOx films (~ 15 nm) prepared by thermal evaporation of SiO in vacuum. It has been shown that furnace annealing at 1000 oC causes phase separation and formation of uniformly distributed Si nanocrystals into a SiO2 matrix. Clockwise hysteresis has been observed in the C-V curves measured and explained by assuming charging and discharging of the NCs with carriers, which tunnel from the Si substrate.

Silicon Oxide Films Containing Amorphous or Crystalline Silicon Nanodots for Device Applications

Тhe impressive recent growth of the portable systems market (mobile PC, MP3 audio player, digital camera, mobile phones, hybrid hard disks, etc.), has increased the interest of the semiconductor industry on non-volatile memory (NVM) technologies. Тhe demand for mobility applications is the main reason for the fast development of NVM technologies and products. Therefore lower power consumption, lower system costs, ever higher capacity and system performance are required. The conventional floating-gate memories satisfy these needs at present but the scaling of these memories is becoming increasingly difficult primarily because reliability problems limiting the bottom (tunnel) oxide to a thickness of around 10 nm.

Influence of Thermal Annealing on the Properties of Sputtered Si Rich Silicon Oxide Films

Thin SiOx films deposited by reactive r.f. magnetron sputtering of Si at partial pressure ratios R between oxygen and argon in the range 15%-0.03% are studied. X-ray photoelectron spectroscopy and Variable angle spectroscopic ellipsometry prove enrichment with Si of the layers deposited at R < 0.5 %. Ellipsometric data give information about the refractive index and extinction coefficient of the films. Atomic Force Microscopy results show that for all samples high temperature annealing at 1000oC leads to a decrease of the surface roughness.

Electrical characterization of MOS structures with self- organized three-layer gate dielectric containing Si nanocrystals

SiOx (x = 1.3) films with thicknesses of 50 and 100 nm deposited on c-Si by thermal evaporation of SiO in vacuum were subjected to N2 or two steps N2, 90%N2+10%O2 annealing at 1000 oC for 60 min. The time of the second (N2+10%O2) annealing step was varied in order to vary the depth to which the SiOx films were intentionally oxidized. The I–V and XTEM results obtained confirm that the suggested two steps annealing leads to a formation of three-layer SiO2/SiO2-Si nanocrystals/SiO2 gate dielectric, which contains Si nanocrystals. The nanocrystals are with a diameter of a ~ 4-5 nm and are embedded in a stoichiometric SiO2 matrix. The I–V measurement show that the current through the gate dielectric is limited by a SiO2 region, close to the top surface, formed during the second annealing step. MOS structures subjected to a two step annealing show larger retention times when charged with electrons/holes in comparison with the control or annealed only in N2 structures.