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To investigate the relation between optical property and size of the nano structure, the band structures, density of states, and optical properties of series nano structures embedded in SiO2 were calculated using the density functional theory-plane waves(DFT-PW) of first-principles method. The results show, the intermediate levels of Ge and Si nanostructure are at about 3.3 eV and 4.3 eV above Fermi...
In this work a very low cost and conventional technique was used to prepare Ge nano/microstructures by means of filling the material inside porous silicon (PS) using thermal evaporator. PS was prepared by anodization of Si wafer in ethanoic hydrofluoric acid (HF).The Ge layer was deposited onto the PS by thermal evaporation.Subsequent annealing at 650°C and 750 C for 30 mins were done to drive in...
GeSiO nanosystems were obtained using two different preparation methods, sol-gel and magnetron-sputtering. Transmission electron microscopy measurements were performed to investigate the films structure. Amorphous and crystalline Ge dots embedded in amorphous silicon dioxide were observed. The Ge concentration in the GeSiO films was by Energy-dispersive X-ray spectroscopy.
We have grown Si/Ge nanodot superlattices via low-pressure chemical vapor deposition in order to analyze their performance as thin-film solar cells. Self-assembled Ge nanodots are included in the base region in order to boost absorption of near-infrared photons and to increase short-circuit current density, Jsc. At a relatively low dot density of 5.5 ?? 109 cm-2, both 20- and 40-period cells exhibited...
It is determined that the content of Ge in the volume of germanium-silicate glass (GSG) influences density of nanocrystalline grains. It is ascertained that germanium atoms are unevenly distributing between separate nanoclusters as well as in the limits of one cluster. The size and density of germanium nanoclusters may be independently checked by the way of changing of germanium content in the composition...
It is shown that the main condition, under which the process of germanium (Ge) nanoclusters and of the solid silicon-germanium solution formation takes place, is the sorption of atoms of silicon (Si) and Ge on the dielectric base. All stages of the process depend on the purity of the initial base, its orientation and chemical composition of the gas mixture. The size of Ge nanoclusters may be independently...
Self-assembled configurations of nanostructures are expected to play an increasingly important role in devices design, as an alternative to conventional microelectronics technology. Conventional techniques are generally limited by the lack of simultaneous control on positioning, density and size uniformity of the nanostructures. To overcome these problems a new substrate based on controlled direct...
The process of formation and properties of Ge-silicate glasses (GSG) in the process of oxidation of the Ge-doped nanostructured polycrystalline silicon films (NSF PCS) has been investigated. The dependences of heating effects in the process of linear heating of grinded GSG are shown.
The process of formation and properties of germanosilicate glass (GSG) films in the process of oxidation of nanostructured polycrystalline silicon doped by germanium films is investigated.
The increasing use of portable electronics and embedded systems has resulted in the need for low-voltage, high-density nonvolatile memory devices. Nanocrystal memories, utilizing the Coulomb blockade effect, have the potential to satisfy such a requirement. The primary motivation in the use of nanocrystal memories is the potential to scale the tunnel dielectric thickness to a small dimension, resulting...
The gradual Ge1-xSix/Si heteronanocrystals on ultra thin SiO2 were fabricated to form the metal-oxide-semiconductor (MOS) memory structure with asymmetric tunnel barriers through combining self-assembled growth and selective chemical etching technique. Charge storage characteristics in such memory structure have been investigated by using capacitance-voltage measurements. The observations demonstrate...
Graphene is a possible candidate for advanced channel materials in future field effect transistors. This presentation gives a brief overview about recent experimental results in the field of graphene transistors for future electronic applications.
The dot and ripple surface topography emerging on Si, Ge and compound semiconductor surfaces during low-energy (les 2000 eV) noble gas ion beam erosion at oblique ion incidence is studied. The results show that there is a much more complex behavior of the surface topography with ion energy, ion fluence, angle of incidence, etc.
MOSFET memory devices with Ge/Si HNCs (hetero-nanocrystal) floating gate were fabricated. A superior performance was demonstrated, including larger storage capability, longer retention time, and faster programming speed, which makes Ge/Si HNCs memories promising candidate to replace Si NCs memories.
Ge Nanocrystallites (nc-Ge) have been formed by 250 keV Ge+74 implantation at fluences of [0.5; 0.8; 1; 2; 3; 4]times1016 atoms/cm2 into 300-nm-thick SiO2 layer thermally grown on p-type Si (100) substrate, followed by thermal treatment at 1000 degC in forming gas atmosphere for 1 hour. All the samples show a broad Raman spectrum with fluences variation as function of the shift Raman. Ge+-dose dependence...
Quantum dots (QDs) grown on semiconductors surfaces are actually the main researchers' interest for applications in the forecoming nanotechnology era like nanotransistors and nanomemories. Novel approaches to form ordered patterns of homogeneous nanostructures consist of natural patterning induced by surface instabilities, as step bunching of Si(111) or misoriented Si(001) surfaces, and of nanolithographic...
We present an extensive study about the formation of Ge nanocrystals by using two-step process deposition by a commercially UHVCVD system. We also investigate the growth duration effect on micro-Raman characterization in SiO2 matrix containing Ge-NCs. FTIR spectroscopy is employed to monitor the amount of various chemical bonds in SiO2 matrix embedded with Ge-NCs under various annealing temperatures...
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