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In this letter, we report on the fabrication and characterization of colored and semitransparent silver nanoparticle layers. A spin coating of silver nanoink is used to deposit silver nanoparticle layers onto substrates. The transmittance and color of the silver nanoparticle layers are significantly dependent on the spin speed and nanoink concentration, owing to variations in the size and distribution of the nanoparticles. Both color variation and efficiency improvement are achieved with the application of silver nanoparticles to semitransparent Si thin-film solar cells, which is associated with the excitation of the dipole or quadruple plasmon modes of the silver nanoparticles.

AlxTi1-xOy (ATO) films were deposited by plasma enhanced atomic layer deposition (PEALD). In the deposition, it was possible to tailor the refractive index and the thickness of films by adjusting the number of cycles used for Al2O3 and TiO2 sublayers. Because optical thickness can be controlled, ATO films will be applicable to optical filters, high reflectivity coating layers and antireflection coating layers.

Hydrogenated microcrystalline silicon (µc-Si:H) film was fabricated by inductively coupled plasma–chemical vapor deposition (ICP–CVD) at 150 °C on ZrO2 gate dielectric which was made by atomic layer deposition (ALD) method. µc-Si:H film with very thin incubation layer less than 10 nm was deposited on ZrO2 film. Polycrystalline ZrO2 played a role of crystal seed layer to enhance the crystalline fraction of µc-Si:H film. Surface roughness of ZrO2 film increased as deposition temperature of ZrO2 was increased. Rougher surface of ZrO2 film provided nucleation site of µc-Si:H film at early growth stage to reduce the thickness of the incubation layer. The crystalline fraction of µc-Si:H film depended on crystallinity of ZrO2. When µc-Si:H film was deposited on ZrO2 of 100 and 50 nm thickness at 250 °C, (200) and (111) peak intensity was increased respectively.

VO2 films showing abrupt metal–insulator transition (MIT) were fabricated on amorphous-film-coated Si wafers by reactive RF-magnetron sputter deposition using a V-metal target, and postdeposition annealing. The amorphous films were thermally grown SiO2 or Al2O3 films deposited by low-temperature plasma-enhanced atomic layer deposition. The effects of the underlayer and chamber pressure governing oxidation ambient on MIT characteristics were investigated. The MIT of VO2 films deposited at 5 mTorr on SiO2 and Al2O3 induced resistance changes of 1.3×104 and 2.3×103, respectively. The resistance change due to MIT was larger than 6.3×103 in an operating pressure range as wide as 5–25 mTorr on SiO2.

We propose a new fabrication process of nano-gap electrode pairs using an atomic-layer-deposited (ALD) sacrificial layer and the shadow deposition technique. In this process, gap width can be precisely controlled by the number of deposition cycles of the ALD process, whereas junction area is defined by the deposition angle of the second electrode material through an overhanging shadow mask on top of the first electrode. In comparison with our previous method, process reliability has been highly improved because the unintentional deposition of the second electrode material on the sidewall of the first electrode is completely prevented. We have fabricated 10 ×10 arrays of n-type polycrystalline silicon (n-poly-Si)/Au nano-gap electrode pairs with gap widths of 6 and 9 nm, which show good insulating properties at room temperature.

Aluminum oxinitride film fabricated by Plasma-enhanced atomic layer deposition (PEALD) was found to possess a large breakdown field, which is necessary for the stable operation of thin film electroluminescent (TFEL) devices. Moreover, aluminum oxinitride is more stable than aluminum oxide films grown by PEALD or by ALD after a postannealing process, which is inevitably required to improve the luminance property of phosphor. Furthermore, aluminum oxinitride films were applied to insulators of ZnS:Mn as well as a ZnS:Tb TFEL device. Resultantly, they show superb stability under a high electric field.

In this study, we report that the metal Cu deposited on a glass substrate is formed into a stable p-type Cu2O film with excellent properties through rapid thermal oxidation (RTO). The pre-deposited Cu film layer went through thermal oxidation in the temperature range of 200–500 °C in O2 and air ambient, and the electrical and optical properties were intensively investigated. The optimized p-type Cu2O film heat-treated at a temperature of 200 °C in an air ambient has a carrier concentration of 1.25×1017 cm-3, mobility of 0.51 cm2 V-1 s-1, and resistivity of 9.86 Ω cm; its optical band gap reaches about 2.4 eV. Using the p-type Cu2O film with i- and n-type amorphous silicon layers, heterojunction thin-film solar cells were fabricated on glass substrates. These transparent solar cells employed Ga-doped ZnO films as top and bottom electrodes. Solar cells with Cu2O film oxidized at 200 °C in an air ambient have an open circuit voltage of 0.36 V, short-circuit current of 15.2 mA/cm2, and photoelectric conversion efficiency of 1.98%.

Ga-doped zinc oxide (GZO) films were deposited using rf magnetron sputter deposition and a Ga2O3(5 wt %)-doped ZnO ceramic target under various deposition conditions. The effects of each deposition condition on the electrical, structural, and optical properties of the GZO films were investigated to obtain a transparent conducting oxide (TCO) with a high transmittance and a low resistivity for a-Si:H thin-film solar cells. Resistivity showed a strong dependence on working pressure and rf power. The lowest resistivity of 1.9×10-4 Ω·cm was obtained at an rf power density of 2.47 W/cm2. The highest figure of merit for the use of TCO was achieved in the 800-nm-thick GZO film [ρ=2.1×10-4 Ω·cm, average transmittance (400–800 nm) = 92.1%] deposited at 10 mTorr and an rf power density of 1.85 W/cm2. These results indicate that the high-performance TCO fabricated in this work is suitable for use as a transparent electrode layer for thin-film solar cells.

Vanadium dioxide (VO2) and vanadium sesquioxide (V2O3) thin films showing an abrupt metal–insulator transition near their typical critical temperature (TC) were successfully fabricated by reactive RF magnetron sputter deposition and subsequent annealing processes. The annealing processes for preparing VO2 and V2O3 films were carried out in 30 mTorr O2 ambient and at a very low pressure (2 ×10-6 Torr), respectively. V2O3 films could be fabricated by the one-step annealing of as-deposited VOx films in contrast to the V2O3 fabrication by the two-step annealing of sol–gel V2O5 films. The annealing temperature for preparing V2O3 films (≥550 °C) was much lower than those reported in earlier works. The dependence of TC on the surface orientation of a single crystalline Al2O3 substrate was also shown for VO2 and V2O3 films. The films fabricated on (1010)-plane Al2O3 substrate showed superior characteristics to those on (0001)-Al2O3.