周期的構造変調層を形成したSiナノ結晶分散薄膜の電気的・光学的性質

Siナノ結晶(nc-Si)をSi酸化物中に分散生成したnc-Si分散薄膜は,光励起により高効率の可視発光を呈する新しい発光材料であるが,電気伝導度が小さく電流注入による発光の実現が困難である。本研究では,発光効率の高い高抵抗層とSi-richな低抵抗層を多層化することにより,高効率発光と伝導度の向上を同時に実現することを目指した。多層構造の形成は,プラズマCVD法によるSiO_x堆積中にO_2供給量を変化させ組成に変調を与えることにより実現した。熱処理後に形成されるナノ結晶のサイズは組成に依存するため,結果として平均結晶サイズにも周期的な空間変調が与えられる。多層化により電気伝導度の向上は確認されたが,積層周期を100nm程度まで小さくしなければ多層化の効果は現れなかった。このため,昨年度の研究成果であるブラッグリフレクタ(300nm周期)による発光スペクトルの先鋭化との同時実現が課題として残った。Nanocrystalline (nc-) Si-dispersed films, which are the silicon oxide thin films including nc-Si dispersively, are a new light-emitting material providing high efficiency visible photolminescence. However, the nc-Si-dispersed films generally have low electrical conductivity, and thus there are difficulties in achievement of light emission by current injection. In this project, we aimed to achieve both high efficiency light emission and high conductivity simultaneously by the formation of periodical multilayers with high-efficiency light-emitting layers and low-resistivity Si-rich layers.The formation of the multilayer structure was realized by modulating oxygen content of the films through a variation of O_2 flow rate. As a result, a spacially periodical modulation of the average size of nc-Si was bought about after high-temperature thermal annealing because the size of nc-Si formed depends on the composition of the films. An increase of the conductivity due to the multilayer structure was confirmed but the effect of multilayer structure observed only for the multilayer that has a period less than 100nm. That was not compatible to the period 〜300 nm of distributed Bragg reflector for 800-nm wavelength region, which is the peak wavelength of photoluminescence. This incompatibility must be solves in future.研究課題/領域番号:11650319, 研究期間(年度):1999-2000出典：「周期的構造変調層を形成したSiナノ結晶分散薄膜の電気的・光学的性質」研究成果報告書　課題番号11650319 (KAKEN：科学研究費助成事業データベース（国立情報学研究所）)　　　本文データは著者版報告書より作

シリコンナノ結晶分散薄膜を用いた微小球光共振器の作製と光学特性解析

本研究では,Siナノ結晶を内包した微小球光共振器の新たな作製方法の確立を目的とする。さらに,その光学的性質について,自然放出光と微小共振器の相互作用に関する共振器量子電気力学的見地からの解析を行うことを目的とした。研究成果の概要は以下の通りである。試料のベースとなるa-SiOx薄膜ならびにa-SiO2薄膜は,それぞれ現有設備の高周波スパッタリング装置にて堆積したもの,あるいは熱酸化により形成したものを用いた。基板は耐熱性を重視してタングステンを用い,堆積膜厚は5・mとした。スパッタリングターゲットには,100mm・のSiO2ターゲット上にSiチップを載せたものを用いた。このSiチップの量によって堆積膜の組成を制御した。堆積したSiOx薄膜を島状に微細加工するために,電子ビーム描画装置によりパターニングを行った。パターンは直径0.5〜20・mの円形とし,リフトオフによってCrマスクパターンを試料上に残した。エッチングには,CF4ガスによる反応性イオンエッチングを用いた。ウェットエッチングによるCrマスク除去の後,走査型電子顕微鏡にて観察を行い,形成されたパターンを確認した。した。最後に,赤外線ゴールドイメージ炉を用い,微細加工により基板上に島状に残したSiOxに対し軟化点温度付近(1200〜1800℃)で加熱処理を行った。試料セルはモリブデン製を用い,熱処理雰囲気は酸化防止のためにアルゴンガスフロー中とした。熱処理条件は,1600℃において2分間が最適であることが分かり,この条件により,エッチング後の円柱形パターンの形状を半球形に変化させることに成功した。しかしながら,光学的な測定結果を得るまでには至らなかった。This research work aimed to establish a novel fabrication method of microsphere optical cavity including silicon nanocrystallites. Then their optical properties are analyzed from a viewpoint of cavity quantum electrodynamic theory with respect to an interaction between spontaneously emitted light and microcavity.Amorphous (α-)SiOx and α-SiO_2 films as bases of samples are deposited using a radio-frequency sputtering method and a thermal oxidation method, respectively. Tungsten substrates are used in order to ensure heat resistance. The thickness of the films were 5μm. The sputtering target was SiO_2 disc with Si tips on it. The composition of the films deposited was controlled by varying the number of Si tips. An electron-beam drawing system was used for microfabrication of the films into island-like patterns. Circular patterns of chromium with 0.5-20μm in diameter were formed on the film by a lift-off process. The film was then etched by CF_4-plasma reactive ion etching. The columner patterns fabricated were checked by scanning electron microscope. Those columner islands of SiOx fims were heated up to around softening point, that is, 1200-1600℃. The samples inserted in a Mo cell were in an atmosphere of Ar gas flow in order to avoid oxidation. The optimal condition of heating was 2 minutes at 1600℃. Under this condition, the columner islands were successfully deformed into hemispherical shapes. However, analysis of their optical properties was difficult at that point in time.研究課題/領域番号:17560306, 研究期間(年度):2005-2006出典：「シリコンナノ結晶分散薄膜を用いた微小球光共振器の作製と光学特性解析」研究成果報告書　課題番号17560306 (KAKEN：科学研究費助成事業データベース（国立情報学研究所）)　　　本文データは著者版報告書より作

Si超微粒子分散薄膜を用いた電界発光素子の作製と基本特性評価

金沢大学理工研究域電子情報通信学系Siサブオキサイド(SiO_x)薄膜を高温熱処理・相分解する事により,Si酸化膜中にSi超微粒子を分散生成した,Si超微粒子分散薄膜(Si-cluster dispersed film:Si-CDF)は,光励起により強い赤色発光を呈し,さらに素子形成および微細加工に適した形態を持つ。本研究は,Si-CDFを発光層に用いて電界発光(EL)素子を作製し,EL発光層としての基本特性を明らかにする事を目的としたものである。EL素子は,Al電極/Si-CDF/低抵抗Si基板の3層構造とした。プラズマCVDにより低抵抗Si基板上にSiO_x(x=1.6)を堆積し,1100℃・1時間の熱アニーリングによってSi超微粒子を折出させた後,Al上部電極を真空蒸着した。ELの励起は,交流電界を印加によって行った。このEL素子は,約3MV/cm(peak to peak)までの印加電圧に耐え,一般にELの励起に必要な電界は印加可能であったと言える。しかしながら,本研究で作製した素子すべてについてELは確認されなかった。Si-CDF自体は光励起により強い発光を示すため,発光中心が存在することは明らかであり,今回ELが観測されなかったのはSi微粒子の励起過程に問題があったと考えられる。光励起の場合は,透明なSiO_2媒質は励起されずSi微粒子が選択的に励起されるが,電界励起の場合,媒質からSi微粒子への励起移動が効率良く行われる必要がある。今回の結果からは,Si微粒子の励起に必要なホットキャリアの媒質中における生成が充分でないことが考えられ,媒質の電気特性(キャリア濃度および易動度)の改善またはSi結晶の体積分率の向上が必要と考えられる。今後は,キャリア注入型EL素子も念頭に入れ,薄膜全体としてみた電気特性の改善を目指す予定である。研究課題/領域番号:08750396, 研究期間(年度):1996出典：研究課題「 Si超微粒子分散薄膜を用いた電界発光素子の作製と基本特性評価」課題番号08750396（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-08750396/）を加工して作

Replacement of cisplatin with nedaplatin in a definitive 5-fluorouracil/cisplatin-based chemoradiotherapy in Japanese patients with esophageal squamous cell carcinoma

Objective: The effects of replacing cisplatin (CDDP) with cis-diammineglycolatoplatinum (nedaplatin, NDP), a second-generation platinum complex, on the pharmacokinetics of 5-fluorouracil (5-FU) were investigated in Japanese patients with esophageal squamous cell carcinoma, who were treated with a definitive 5-FU/CDDP-based chemoradiotherapy

Postmarketing surveillance of safety and effectiveness of etanercept in Japanese patients with rheumatoid arthritis

Our aim was to evaluate real-world safety and effectiveness in a 6-month postmarketing surveillance study covering all Japanese patients with rheumatoid arthritis (RA) who received etanercept during a 2-year period. Data for 13,894 patients (1334 sites) enrolled between March 2005 and April 2007 were collected. Adverse events (AEs) and serious adverse events (SAEs) were reported in 4336 (31.2%) and 857 (6.2%) patients, respectively. The most frequent AEs were injection site reactions (n = 610, 4.4%) and rash (n = 339, 2.4%), whereas pneumonia (n = 116, 0.8%) and interstitial lung disease (n = 77, 0.6%) were the most frequent SAEs. Significant improvement in the proportion of patients with a good European League Against Rheumatism (EULAR) response was observed from week 4 (17.6%) to week 24 (31.6%) (p < 0.001); 84.3% of patients had good or moderate EULAR responses at week 24. The percentage of patients achieving remission increased significantly from week 4 (9.3%) to week 24 (18.9%) (p < 0.001). Patients with early moderate RA were less likely to experience SAEs and were more likely to achieve remission compared with patients with more severe disease. The safety and effectiveness of etanercept was demonstrated in Japanese patients in one of the largest observational trials conducted thus far in RA patients treated with biologics

Roles of SiH4 in growth, structural changes and optical properties of nanocrystalline silicon thin films

金沢大学理工研究域電子情報通信学系Nanocrystalline silicon (ns-Si) thin films deposited through plasma-enhanced chemical vapor deposition technique were studied. These films were grown at low deposition temperature of 200°C and at different silane flow rates ([SiH4]). Characterization of these films with Raman spectroscopy, x-ray diffraction and atomic force microscopy revealed that no films deposited at [SiH4]=0.0sccm. In addition, the structural change from an amorphous to a nanocrystalline phase at [SiH4]=0.2sccm. The Fourier transform infrared spectroscopic analysis showed at low values of [SiH4](0.1sccm), no hydrogen incorporated in the nc-Si thin film. However, the intensity of the spectra around 2100 cm-1 is likely to decreases with increasing [SiH4]. We have observed photoluminescence (PL) at room temperature in the range of 1.7 eV to 2.4 eV for all the films. Presence of the very small crystallites (the size less than 20 nm) responsible for quantum confinement effect. Variations of the PL intensity, width and position are well correlation with the structural properties of the films such as crystalline size, crystalline volume fraction, and hydrogen content. Furthermore, the PL emissions also showed correlation with the distribution of spherical grains with the size below 50 nm distributed on the films surface. © 2011 American Institute of Physics.Conference Pape

Inversion channel diamond metaloxide-semiconductor field-effect transistor with normally off characteristics

We fabricated inversion channel diamond metal-oxide-semiconductor field-effect transistors (MOSFETs) with normally off characteristics. At present, Si MOSFETs and insulated gate bipolar transistors (IGBTs) with inversion channels are widely used because of their high controllability of electric power and high tolerance. Although a diamond semiconductor is considered to be a material with a strong potential for application in next-generation power devices, diamond MOSFETs with an inversion channel have not yet been reported. We precisely controlled the MOS interface for diamond by wet annealing and fabricated p-channel and planar-type MOSFETs with phosphorus-doped n-type body on diamond (111) substrate. The gate oxide of Al2O3 was deposited onto the n-type diamond body by atomic layer deposition at 300 °C. The drain current was controlled by the negative gate voltage, indicating that an inversion channel with a p-type character was formed at a high-quality n-type diamond body/Al2O3 interface. The maximum drain current density and the field-effect mobility of a diamond MOSFET with a gate electrode length of 5 μm were 1.6 mA/mm and 8.0 cm2/Vs, respectively, at room temperature. © The Author(s) 2016

Safety and effectiveness of switching from infliximab to etanercept in patients with rheumatoid arthritis: results from a large Japanese postmarketing surveillance study

Finding an effective treatment strategy for rheumatoid arthritis (RA) patients who have not benefited from previous tumor necrosis factor–α antagonist treatment is important for minimizing RA disease activity and improving patient outcomes. The aim of this study was to compare the safety and effectiveness of etanercept in patients with and without infliximab (IFX) treatment experience. Patients (n = 7,099) from a large postmarketing observational study of etanercept use in Japan were divided into 2 cohorts based on previous IFX use (pre-IFX and non-IFX). Baseline characteristics were assessed in each cohort. Adverse events (AEs) and European League Against Rheumatism (EULAR) responses were monitored every 4 weeks for 24 weeks. At baseline, pre-IFX patients were younger and had fewer comorbidities and a shorter RA duration than non-IFX patients. During the study, pre-IFX patients received concomitant methotrexate more often than non-IFX patients. The incidence of AEs and serious AEs were significantly lower in pre-IFX patients, as was the percentage of patients who discontinued treatment. Both cohorts had significant improvement (P < 0.001) in EULAR responses at the end of the treatment period. This study demonstrated that etanercept was effective and well tolerated in active RA patients with and without prior IFX treatment