The Si surface charge sheet density of the p-Si/Si0.81 Ge0.19/Si inverted remote doped structures is evaluated in this paper. Owing to the existence of a quantum well (QW) in the valance band in the alloy layer (SiGe) of this structure, a two-dimensional hole gas (2DHG) is formed near the Si/SiGe/Si lower (Inverted) interface. The area (sheet) density nh of 2DHG, which depends on the Ge content and other structural parameters in the alloy, is strongly affected by the surface charge density nsur on the Si cap layer thus, increasing in proportional to the cap thickness. It can be concluded, through theoretical and experimental comparison, that the Si surface charge density in the structures under study, increases within the range of [(1-2.5)±0.2] x 1011/cm2 as the cap becomes thinner (400-150nm). Moreover, the position of Fermi level with respect to valance band edge at the surface is estimated to be DEFV=(0.5±0.05) eV.

The wafer bonding process has many applications in the fabrication of microelectronic, optoelectronic, power and microinachined devices. In this article fusion bonding of silicon, wafers and study of their interface are reported for the first time in Iran. Also, the bonding of two silicon wafers, with one (or both) of the wafers having a thermally grown silicon dioxide layer, has been performed and tested.

In this work, the epitaxially grown, lattice–matched p-Si/Si1-xGex/Si inverted remote doped structures have been characterized using X-ray and electrical techniques. The Si cup layer thickness (lc) and Ge content (x) have been determined from computer simulation of intensity and angular sepration of (004) peaks observed in the X-ray diffraction pattern due to misorientaion of corresponding Bragg planes of Si and SiGe layers. On the other hand, a quasi two dimensional hole gas (2DHG) is formed in the compressively strained alloy of these structures and its areal density (ns) has been measured by Hall expriment and can be controlled by applying a voltage (Vg) to the artificial gate. In the electrical technique, x and lc chractristics have been obtained using theoretical calculations of the linear dependence of ns versus Vg. Finally, the uncertainity and partial inconsistent of the results have been explained in terms of the affecting effects.

In this paper, the optical properties of laterally oriented core-shell nanowire silicon solar cells (NWSCs) are optimized. The optimum structure consists of an array with non-uniform hexagonal nanowires (NWs). Each NW is constructed from an amorphous silicon layer sandwiched between two crystalline silicon layers. In order to improve the light absorption and short circuit current density (Jsc) of NWSC, a particle swarm optimization (PSO) algorithm is used to optimize the geometrical parameters of NWs. It is shown that the optimized structure has advantageous performance in terms of light absorption and Jsc. Finally, a multiple structure composed of two NWs with different morphologies and the optimized dimensions is proposed to utilize NWSCs better.

The properties of L10-FePt nanoparticles can be improved in the presence of MgO and Ag interlayers in direct sputtering and annealing method, respectively. Such properties are crystal and compound ordering, nanostructure and crystal orientation. In this work, FePt nanoparticles in ferromagnetic L10-fct phase were synthesized using sputtering method on Ag and MgO layers. According to XRD analyses, the impact of the presence of these two kinds of interlayer on crystal structure and its orientation has been investigated. Furthermore, the effect of the presence of 10% Ag on these properties has been studied and their granular layer nanostructures were characterized through the FE-SEM analysis. The results show that the presence of Ag as nanocompound and interlayer is desirable on declining the transition temperature and controlling the size during annealing. The presence of MgO as a sublayer in direct synthesis leads to the formation of 10 nm monosize smaller nanoparticles. According to VSM analysis, MgO and Ag sublayers have increased the magnetic coercivity of the FePt nanoparticles by 3. 4 times and 3. 7 times, respectively.

Silicon (Si) is one of the beneficial elements for plants, which improves quantity and quality of yield, decreases evaporation and transpiration and enhances plant resistance to abiotic stresses. In order to evaluate the effect of Si and nano-silicon (N-Si) on growth, morphological and photosynthesis attributes of tomato, cultivar Falcato, an experiment was carried out in a hydroponic system, based on a completely randomized design, with two Si and N-Si levels (1 and 2 mM) and Si-free nutrient solution (as control), and four replications. Such traits as chlorophyll index (SPAD) photosynthesis, nutrient uptake, stem diameter, relative water content and morphological changes like density of trichomes were measured during the experiment. At the end of the experiment, fresh and dry weights and root volume were measured. Results revealed that Si was more effective than N-Si on fresh weight and mesophyll conductance. Concentrations of 1 and 2 mM Si increased fresh weight and mesophyll conductance, respectively. However, this concentration did not affect dry weight and relative water content significantly. N-Si was more effective than Si on photosynthesis and photosynthetic relative water content. The highest photosynthesis and lowest transpiration rate was measured in 2mM N-Si. Application of Si and N-Si decreased relative water content and the least water uptake was in 2mM N-Si treatment. In conclusion, Si or N-Si, with 20-30 nm particle diameter and optimum tomato growth conditions (without abiotic stresses) increased photosynthesis, fresh weight, relative water content and decreased nutrient solution uptake under hydroponics.