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An amorphous silica layer containing Mo component (a-SiOx(Mo) ∼ 3.5–4.0 nm) is naturally formed in the process of evaporating MoO3 power onto n-type silicon, which plays a significant role on the non-equilibrium carriers’ transport of MoOx/n-Si heterojunction photovoltaic device. The electronic structure and the charge transition levels of the amorphous silicon oxide doped with Mo are derived from density functional theory. The density of states show that the five local states are existed in the band gap of amorphous silicon oxide, caused by the hybridization of Mo 4d orbital and O 2p orbital. The charge transition level of e(+1/0) is located at 3.59 eV above the valance band maximum of a-SiO2, which could be a passageway of holes produced in the opto-electric conversion. Defects level-assisted quantum transport mechanism is put forwarded to explain hole transport phenomenon in the MoOx/SiOx(Mo)/n-Si PV device.

On the basis of a photon-assisted high frequency capacitance–voltage ( C – V ) method (1 MHz C – V ), an effective approach is developed to evaluate the average interface state density ( D it ) of an ITO–SiO x /n-Si heterojunction structure. Tin-doped indium oxide (ITO) films with different thicknesses were directly deposited on (100) n-type crystalline silicon by magnetron sputtering to fabricate semiconductor–insulator–semiconductor (SIS) hetero-interface regions where an ultra-thin SiO x passivation layer was naturally created. The morphology of the SiO x layer was confirmed by X-ray photoelectron spectroscopy depth profiling and transmission electron microscope analysis. The thinness of this SiO x layer was the main reason for the SIS interface state density being more difficult to detect than that of a typical metal–oxide–semiconductor structure. A light was used for photon injection while measuring the C – V of the device, thus enabling the photon-assisted C – V measurement of the D it . By quantifying decreases of the light-induced-voltage as a variation of the capacitance caused by parasitic charge at interface states the passivation quality within the interface of ITO–SiO x /n-Si could be reasonably evaluated. The average interface state density of these SIS devices was measured as 1.2–1.7 × 10 11 eV −1 cm −2 and declined as the passivation layer was made thicker. The lifetime of the minority carriers, dark leakage current, and the other photovoltaic parameters of the devices were also used to determine the passivation.

A silicon based ternary compound was supposed to be solid synthesized with In, Si and O elements by magnetron sputtering of indium tin oxide target (ITO) onto crystal silicon substrate at 250 °C. To make clear the configuration of the intermediate region, a potential method to obtain the chemical bonding of Si with other existing elements was exploited by X-ray photoelectron spectroscopy (XPS) instrument combined with other assisted techniques. The phase composition and solid structure of the interfacial region between ITO and Si substrate were investigated by X-ray diffraction (XRD) and high resolution cross sectional transmission electron microscope (HR-TEM). A photovoltaic device with structure of Al/Ag/ITO/SiOx/p-Si/Al was assembled by depositing ITO films onto the p-Si substrate by using magnetron sputtering. The new matter has been assumed to be a buffer layer for semiconductor-insulator-semiconductor (SIS) photovoltaic device and plays critical role for the promotion of optoelectronic conversion performance from the view point of device physics.

Averaged over wavelength range from 500 to 1600 nm at normal incidence, the reflection losses of silicon wafer as master mold are reduced from original 35% to only 0.2% after integrating surface moth-eye structures, and glass slide suppresses the reflection from 7.5% to near 0.4% after incorporating polymer-based moth eyes on double side by replica molding that enables transferring moth eyes from master mold of silicon onto any substrate. An outstanding anti-reflective property out to large incident angles is realized with the average reflection below 0.5% until 50°, below 2.5% at 60° and below 7.5% at 70°, which holds promise for solar cell application.

The effect of rapid thermal annealing (RTA) on the compositional ratio of atoms and interfacial zone of Cu(In,Ga)Se 2 (CIGS) solar cells was systematically studied using X-ray photoelectron spectroscopy. The RTA treatment induced the diffusion of Al, Zn, and Se atoms, which increased the compositional ratio of these atoms in the corresponding layer. The ratio and characteristics of Cu/(In + Ga) and Ga/(In + Ga) were further modulated to attain higher efficiency in the devices. Furthermore, the width of the interfacial zone decreased at the Mo/CIGS interface because the diffusion depth of the Se atoms contracted from 1300 nm to 1200 nm. After RTA treatment, the absolute efficiency of the CIGS solar cells was enhanced by 1.2%. Our results suggest that RTA treatment reduces series resistance, optimizes the position of the minimum bandgap in the CIGS thin film, and improves the crystallinity of the CIGS thin film, which is responsible for the improvement in conversion efficiency.

Alternately Er doped Si-rich Al 2O 3 (Er:SRA) multilayer film, consisting of alternate Er-Si-codoped Al 2O 3 (Er:Si:Al 2O 3) and Si-doped Al 2O 3 (Si:Al 2O 3) sublayers, has been synthesized by co-sputtering from separated Er, Si, and Al 2O 3 targets. The dependence of Er 3+ related photoluminescence (PL) properties on annealing temperatures over 700-1100 °C was studied. The maximum intensity of Er 3+ PL, about 10 times higher than that of the monolayer film, was obtained from the multilayer film annealed at 950 °C. The enhancement of Er 3+ PL intensity is attributed to the energy transfer from the silicon nanocrystals in the Si:Al 2O 3 sublayers to the neighboring Er 3+ ions in the Er:Si:Al 2O 3 sublayers. The PL intensity exhibits a nonmonotonic temperature dependence: with increasing temperature, the integrated intensity almost remains constant from 14 to 50 K, then reaches maximum at 225 K, and slightly increases again at higher temperatures. Meanwhile, the PL integrated intensity at room temperature is about 30% higher than that at 14 K. © 2011 Elsevier B.V. All rights reserved., This work was supported by the National Natural Science Foundation (Nos. 50602029, 60425411 and 10621063) of China and the Ministry of Science and Innovation of Spain (SB2005-003), and also supported by the special funds for Major State Basic Research Project No. 2011CB925601 of China, Shanghai Municipal Education Commission, Shanghai Science and Technology Commission and Shanghai Leading Academic Discipline Project (No. S30105).

Structural and optical properties of Sc-doped ZnO films grown by RF magnetron sputtering at different substrate temperatures were investigated. All the ZnO:Sc films are polycrystalline with the hexagonal wurtzite structure. X-ray diffraction patterns of the films showed that the doped-films have (0 0 2) as preferred orientation when the deposition temperature was increased from 250 °C to 300 °C. All the films are in a state of compressive stress, whereas the stress decreases gradually with increasing substrate temperature. The average transmittance of these films was above 90% in the wavelength range from 400 nm to 800 nm. The optical band gap of these films was determined. The optical constants of these films were determined using transmittance and reflectance spectra.