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The large area and high-quality two-dimensional molybdenum disulfide (2D-MoS2) film has been synthesized by a modified single-zone chemical vapor deposition technique. The influence of gas environment, reaction temperature and gap distance (between MoO3 precursor and substrate) on 2D-MoS2 growth were systematically investigated. A stable gas environment was prerequisite for the formation of 2D-MoS2, and it can be achieved by adjusting the pressure and flow rate of N2 in the furnace tube, which was numerical estimated via Antoine equation. The thickness, quality (uniformity and crystallinity), roughness, and chemical composition of the MoS2 nano-film were characterized by the optical microscopy, scanning electron microscope, Raman spectroscopy, Atomic force microscope, and X-ray photoelectron spectroscopy, respectively. The results showed that the quality of MoS2 nano-film was greatly influenced by the nucleation density on the substrate, which could be controlled by modulating the reaction temperature and gap distance. Moreover, a “frustum-like” model was established to match the practical reaction situation and clarify the internal relationship among reaction temperature, gap distance and the nucleation density of MoS2 film. Finally, a high-quality monolayer MoS2 nano-film, at 800 °C with a gap distance of 3.5 mm, was obtained and verified by experimental and numerical analyses.

Few layer graphene were synthesized on different substrates by radio frequency plasma enhanced chemical vapor deposition in the absence of any catalyst under 300 °C. Raman spectral characterization verified the bonding form of the films to be mostly sp 2. The principal chemical mechanisms relevant to the growth of graphene from gaseous hydrogen and hydrocarbon species are presented. The kinetic processes during the activation and transport of the gaseous species are described. Furthermore, the effects of substrate treatment in the course of growth are analyzed. We demonstrated that the differences in growth conditions reveal different mechanisms of growth of graphene by chemical vapor deposition. Nevertheless, the overall thermodynamic and dynamics principles are identical. It is reasonable to obtain few layer graphene films by using methane alone without H2 as source gas. Moreover, graphene films of various feature and structures for different purposes can be achieved controllably by modulating the kinetic factors. Also, these graphene films can be used in many photoelectric devices such as solar cells and photodetectors.

Carbon films with the thicknesses varying from 10 to 600 nm in the architecture range of carbonaceous graphene to graphitic bonding were synthesized on Si wafer. The films were prepared by radio frequency plasma enhanced chemical vapor deposition under 300 °C without any catalyst and hydrogen-assistant ambient as well. The films found to be composed of microcrystalline graphene and graphite inclusions with a maximum graphene film size of 2 µm. Raman spectral characterization verified the bonding form of the graphene–graphitic films to be mostly sp2. In this work, the complicated transfer printing process for carbon/silicon (C/Si) devices and the quality degradation of the hybrid films were avoided by the direct deposition of the carbonaceous films on Si substrate. The current–voltage feature of the devices manifested that the devices possess an excellent rectifying behavior in dark and the characteristic of photovoltaic in the illumination (known as solar cells).

Amorphous indium-tin-oxide (a-ITO) film was deposited by radio-frequency (RF) magnetron sputtering at 180°C substrate temperature on the texturized p-Si wafer to fabricate a-ITO/p-Si heterojunction solar cell. The microstructural, optical and electrical properties of the a -ITO film were characterized by XRD, SEM, XPS, UV-VIS spectrophotometer, four-point probe and Hall effect measurement, respectively. The electrical properties of heterojunction were investigated by I–V measurement, which reveals that the heterojunction shows strong rectifying behavior under a dark condition. The ideality factor and the saturation current density of this diode are 2.26 and 1.58×10−4 A cm−2, respectively. And the value of IF/IR (IF and IR stand for forward and reverse currents, respectively) at 1 V is found to be as high as 21.5. For the a-ITO/p-Si heterojunction solar cell, the a-ITO thin film acts not only as an emitter layer, but also as an anti-reflected coating film. The conversion efficiency of the fabricated a-ITO/p-Si heterojunction cell is approximately 1.1%, under 100 mW cm−2 illumination (AM1.5 condition). And the open-circuit voltage (Voc), short-circuit current density (JSC), filll factor (FF) are 280 mV, 9.83 mA cm−2 and 39.9%, respectively. Because the ITO film deposited at low temperature is amorphous, it can effectively reduce the interface states between ITO and p-Si. The barrier height and internal electric field, which is near the surface of p-Si, can effectively be enhanced. Thus we can see the great photovoltaic effect.

The structural and mechanical factors that control the torsion fracture behavior of cold-drawn eutectoid steel wires are examined. Two types of the fracture are identified; namely, flat- and cleavage-type. Torsion cracks are found to initiate in ferrite and propagate along the ferrite/cementite interface. The shear stress distribution within the wires is affected not only by the applied torque, but also by the residual stress. The maximum shear stress occurs halfway from center to the surface, where the cracks initiated. The growth of torsion cracks is sensitive to the orientation of cementite lamellas in pearlite grains. The influence of thermal history on the occurrence of cleavage fracture is ascertained, with the assistance of atom probe. It shows that the cleavage fracture results from a decrease in dislocation mobility, caused by thermally activated diffusion of carbon atoms into ferrite.

In order to realize ultralow surface reflectance and broadband antireflection effects which common pyramidal textures and antireflection coatings can’t achieve in photovoltaic industry, we used low-cost and easy-made Ag-catalyzed etching techniques to synthesize silicon nanowires (SiNWs) arrays on the substrate of single-crystalline silicon. The dense vertically-aligned Si NWs arrays are fabricated by local oxidation and selective dissolution of Si in etching solution containing Ag catalyst. The Si NWs arrays with 3 μm in depth make reflectance reduce to less than 3% in the range of 400 to 1000 nm while reflectance gradually reached the optimum value with the increasing of etching time. The antireflection of Si NWs arrays are based on index-graded mechanism: Si NWs arrays on a subwavelength scale strongly scatter incident light and have graded refractive index that enhance the incidence of light in usable wavelength range. However, surface recombination of Si NWs arrays are deteriorated due to numerous dangling bonds and residual Ag particles.

Three kinds of methods (0.08 mol/L iodine in ethanol, SiNx:H, and 40% HF) are used to passivate solar-grade Czochralski (Cz) silicon wafers. Thereafter, minority carrier lifetime and Fe-B pair density of the wafers are measured using the microwave photo-conductance decay (μ-PCD) technique. Based on the measured minority carrier lifetime, it is found that the passivation quality achieved by 0.08 mol/L iodine in ethanol is the best, while that by 40% HF solution is the worst. For the identical wafer, the density distribution of Fe-B pairs is different when different passivation methods are used. When the wafers are passivated by SiNx:H, there exists a close correlation between the distribution of minority carrier lifetime and the concentration distribution of Fe-B pairs. Furthermore, for wafers with high-quality passivation, there is a strong correlation between the recombination center concentration and the Fe-B pair density. All the analyses verify that the surface passivation quality of wafers influences the measurement results of minority carrier lifetime, Fe-B pair density and recombination center concentration.

In this study, we report on the realization of ultraviolet response enhancement in PV cells through the structure of ITO/SiO2/np-Silicon frame (named as SINP), which was fabricated by the state of the art processing. The fabrication process consists of thermal diffusion of phosphorus element into p-type texturized crystal Si wafer, thermal deposition of an ultra-thin silicon dioxide layer (15–20A) at low temperature, and subsequent deposition of thick In2O3:SnO2 (ITO) layer by RF sputtering. The structure, morphology, optical and electric properties of the ITO film were characterized by XRD, SEM, UV-VIS spectrophotometer and Hall effect measurement, respectively. The results showed that ITO film possesses high quality in terms of antireflection and electrode functions. The device parameters derived from current-voltage (I–V) relationship under different conditions, spectral response and responsivity of the ultraviolet photoelectric cell with SINP configuration were analyzed in detail. We found that the main feature of our PV cell is the enhanced ultraviolet response and optoelectronic conversion. The improved short-circuit current, open-circuit voltage, and filled factor indicate that the device is promising to be developed into an ultraviolet and blue enhanced photovoltaic device in the future.

The titanium nitride (TiNx) thin film with a controllable surface structure was fabricated by the dc-reactive magnetron sputtering technique, and the variation of microstructure in the surface layer with the energy of condensed adatom was investigated through X-ray diffraction (XRD) pattern and transmission electron microscope (TEM). It was found that the lattice parameters and the full width at half maximum (fwhm) of XRD peak on the top layers in the preferred orientation of (111) and (002) were closely correlated to the impacting induced phase composition, compressive strain, crystallite size and the fault density of the thin films. In the theory, a new means was used to model the atomistic process of per condensed adatom. The average energy at least in the minimum energy state of the incorporate adatom on TiN surface layer was statistically formulized through a careful consideration of dynamical process, which properly interpreted the experimental observations.