The gamma phase of copper(I) iodide (γ-CuI) is a p-type semiconductor with a wide bandgap (Eg ≈ 3.1 eV). Conventionally, γ-CuI thin films have been synthesized by the iodination of Cu thin layers with iodine vapor. However, γ-CuI films fabricated by this method have a rough surface and thus frosted-glass-like appearance, which make it difficult to apply this material to transparent electronics. In this paper, a simple new method is proposed for the synthesis of truly transparent p-type γ-CuI films. The chemical reaction between Cu3N thin films and solid-phase iodine at 25 ºC was found to yield highly transparent polycrystalline γ-CuI films with shiny appearance. The γ-CuI films fabricated by this method had root-mean-square roughness values of 8-12 nm, which are less than one-third of those for γ-CuI films synthesized by the conventional method. As a result, specular transmittance of >75% in the visible region was attained. An as-prepared film had a resistivity (ρ) of 3.1 × 10 -2 Ω cm, hole density (nh) of 8.9 × 10 19 cm -3 , and mobility (μ) of 2.4 cm 2 V -1 s -1 . Mild heat treatment at 100-150 ºC under an inert atmosphere was found to suppress nh and enhance μ. The heat-treated films had μ values of 9-10 cm 2 V -1 s -1 , which are comparable to those of other wide-bandgap p-type semiconductors grown epitaxially at high temperatures above 400 ºC. These findings would assist studies on applications of γ-CuI thin films in transparent electronics.

We have investigated electronic band structure of a transparent conducting oxide, Nb-doped anatase TiO2 (TNO), by means of first-principles band calculations and photoemission measurements. The band calculations revealed that Nb 4d orbitals are strongly hybridized with Ti 3d ones to form a d-nature conduction band, without impurity states in the in-gap region, resulting in high carrier density exceeding 1021 cm-3 and excellent optical transparency in the visible region. Furthermore, we confirmed that the results of valence band and core-level photoemission measurements are consistent with prediction by the present band calculations.

Nb-doped anatase TiO2 [Ti0.94Nb0.06O2 (TNO)] films with high electrical conductivity and transparency were fabricated on nonalkali glass using pulsed laser deposition and subsequent annealing in a H2 atmosphere. The amorphous films as deposited on unheated substrates were found to crystallize, forming polycrystalline films at around 350°C. The films annealed at 500°C showed resistivity down to 4.6×10−4Ωcm at room temperature and optical transmittance of 60%–80% in the visible region, which are comparable to those of epitaxial films. These results indicate that TNO films have the potential to be practical transparent conducting oxides that could replace indium tin oxide.

resulting in relatively low data throughput. On the other hand, another type of the new memories based on a solid state We report a novel nonvolatile dual-layered electrolytic electrolyte [5], in which ions such as Ag+ or Cu+ move along resistance memory composed of a conductive Cu ion the applied field and form the conductive bridge in the activated layer and a thin insulator for the first time. An electrolyte, is a promising candidate from the viewpoints of ON/OFF mechanism of this new type memory is postulated high speed switching and low set/reset current. Previous as follows: Cu ions pierce through the insulator layer by studies on the memories, however, seem to show their applied electric field, the ions form a Cu conductive bridge in insufficient retention. the insulator layer, and this bridge dissolves back to the ion To realize both high speed switching and sufficient activated layer when the field is reversed. The 4 kbit memory retention, we have newly developed a dual-layered array with IT-IR cell structure was fabricated based on 180 electrolytic resistance memory utilizing Cu conductive bridge nm CMOS process. Set/reset pulses were 5 ns, 110 gtA and 1 combined with a thin insulator. ns, 125 gA, respectively. Those conditions provide large set/reset resistance ratio of over 2 orders of magnitude and Memory Design satisfactory retention. Essential characteristics for high capacity memories including superb scalability down to 20In a solid state electrolytic memory, metallic ions such as nmo, sufficient endurance up to 107 cycles and preliminary Ag+ or Cu+ play an essential role in fast forming a conductive data for 4-level memory are also presented. These bridge when the electric field is applied. But without the field, characteristics promise the memory being the next generation the bridge should steadfastly keep the shape for the data high capacity nonvolatile memory even before the scaling retention. It seems hard to solve these incompatible limitation of flash memories is encountered. characteristics within a single layer. Therefore we divided the role into respective two layers: the conductive ion activated Introduction layer and the resistance change layer of the insulator as shown in Fig. 1. The resistance change layer is thin enough An imminent scaling limit of flash memories accelerates for the activated ions to pierce through the layer rapidly in the search for the new memories and so far several types of the electric field. The conductive bridge is stable in the layer resistive memories are proposed, such as phase change when no electric field is applied. When the reverse field is memory [1, 2], oxide base resistance change memory [3, 4] applied, the bridge is dissolved back to the ion layer, where and so on. However, each memory seems to have inherent both the electric field and joule heat are thought to be main drawbacks such as large reset current and/or slow set speed, driving forces. Because the insulator layer is thin enough, o o a %^o Cu od 1 l z | CT e | og g uC Gd Cu-Te base conz u...

The development and properties of titanium dioxide (TiO 2 )based transparent conducting oxides (TCO), which exhibit properties comparable to those of In 2-x Sn x O 3 (ITO), are reviewed in this article. An epitaxial thin film of anatase Ti 0.94 Nb 0.06 O 2 exhibited a resistivity (r) of 2.3 Â 10 À4 V cm and internal transmittance of $95% in the visible light region. Furthermore, we prepared polycrystalline films with r of 6.4 Â 10 À4 V cm at room temperature on glass substrates by using sputtering. We focus on characteristics unique to TiO 2based TCO, such as a high refractive index, high transmittance in infrared, and high stability in reducing atmospheres. Possible applications of TiO 2 -based TCOs, as well as the mechanism of the transparent conducting properties found in this d-electronbased TCO, are discussed in this review.Photograph showing TiO 2 -based TCO on a transparent plastic film. Note that the film appears greenish due to interference in the film originating from its high refractive index. This high refractive index is one of the unique characteristics of TiO 2based TCO.

Transparent p‐type CuI layers with high hole mobility can be fabricated on flexible plastic sheets, a system which has been unattainable with p‐type transparent oxide semiconductors. Mildly heat‐treated CuI layers have mobilities of ≈20 cm2 V−1 s−1, which are comparable to those of p‐type GaN epilayers. Highly transparent p–n diodes with sufficient rectification ratio (106) can be manufactured by employing a heterojunction of p‐type CuI and amorphous n‐type In‐Ga‐Zn‐O layers on plastic sheets. Thus, CuI can be regarded as an excellent transparent p‐type semiconductor for flexible transparent electronics.

The synthesis of crystals of a zinc-and tin-based earthabundant element nitride (ZnSnN 2 ) semiconductor was successfully achieved via a metathesis reaction under high pressure. Pressures exceeding 5.5 GPa were required to obtain single-phase crystals. The material's bandgap was determined to be 1.4 eV, which is ideal for photovoltaic absorbers and visible light-active photocatalysts. The decomposition temperature of the material was estimated to be approximately 350-400°C at atmospheric pressure. Finally, the chemical stability of the material against alkali and acid solutions was sufficient for photovoltaic and photocatalytic applications.

The transport properties of a d-electron-based transparent conducting oxide, Nb-doped anatase Ti1−xNbxO2, were investigated as a function of the Nb content x. From optical resistivity spectra, the static effective mass was evaluated to be ∼0.4m0 in the low-carrier-concentration (ne) regime, which is approximately the same as those of conventional transparent conducting oxides (TCOs), and two orders of magnitude smaller than that reported for rutile TiO2. The Hall mobility at room temperature, which is maximized at around x=0.01 (ne∼1021cm−3), was found to be mainly dominated by optical phonon scattering unlike that of other TCOs.