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61.
1,3,5,7-Tetramethylcyclotetrasiloxane (H4) was deposited on silica gel at 80°C by utilizing a chemical vapor deposition (CVD) method, where it was catalytically polymerized to form a surface coating of polymethylsiloxane (PMS). Treated silica gel (PMS-Si) increased in weight up to a plateau level, and there was no further increase with increasing reaction time. The film of PMS was partially cross linked; typical values of crosslinking ratio and film thickness were 2% and 0.6 nm, respectively. An anionic ion exchanger containing diethylamino groups was synthesized from PMS-Si by hydrosilylation of allyl glycidyl ether followed by treatment with diethylamine. Its structure was confirmed by13C and29Si CP/MAS NMR spectroscopy and FT-IR spectrophotometry. Characterization of silica gel (DEA-Si) modified with diethylamino group was evaluated by a packing of the column for liquid chromatography. As a mixture of five nucleotides was completely separated, it was recognized that DEA-Si was operated by ion exchange action. Because the surface of the silica gel was covered with hydrophobic PMS, the peak heights and retention times did not change after washing of the column with alkaline solution. 相似文献
62.
功能性超薄有序分子沉积膜的制备及其结构研究 总被引:14,自引:4,他引:14
1991年G.Decher等首次探讨了阴阳离子与聚电解质交替沉积制备有机超薄膜的方法。我们在完善成膜技术和发展成膜基质的基础上,详细研究了其成膜过程与膜的结构,并定义这种新的自组装超薄有序膜为分子沉积膜——MD膜。MD膜是利用阴阳离子的静电吸附反应特性,通过相反离子体系的交替分子沉积制备的层状有序自组装多层超薄膜。需要指出的是,分子沉积既是有机超薄膜的制备技术,本身又是一种自组装超薄有序膜。MD膜制备工艺简单,热稳定性和长期稳定性好,不受基体形状与面积限制。 相似文献
63.
《Electroanalysis》2004,16(16):1305-1310
A novel amperometric biosensor was constructed for the determination of phenols in pure organic phase. This biosensor was fabricated by immobilizing tyrosinase in a titania sol‐gel membrane which was obtained with a vapor deposition method. This method was facile and avoided the calcination step needed in conventional titania sol‐gel process. The titania sol‐gel membrane could effectively retain the essential water layer around the enzyme molecule needed for maintaining its activity in organic phase. The experimental parameters such as solvent and operating potential were optimized. At ?100 mV this biosensor showed a good amperometric response to phenols in pure chloroform without any mediator and rehydration of the enzyme. For catechol determination the sensor exhibited a fast response of less than 5 seconds. The sensitivity of different phenols was as follows: catechol > phenol > p‐cresol. Additionally, the apparent Michaelis‐Menten constants of the encapsulated tyrosinase to catechol, phenol and p‐cresol were found to be 0.15±0.003, 0.17±0.008 and 0.21±0.004 mM, respectively. The biosensor had also good reproducibility and stability. This work provided a promising platform for the construction of pure organic phase biosensors and the determination of substrates with poor water solubility. 相似文献
64.
D. K. Wickenden T. J. Kistenmacher J. Miragliotta 《Journal of Electronic Materials》1994,23(11):1209-1214
The magnitude of the χ xxxx (3) element of the third-order optical susceptibility was measured in a series of wurtzite phase GaN nucleation layers (~450Å) deposited on (00.1) sapphire at 540°C and annealed to various temperatures up to 1050°C. The nonlinear optical response exhibited a significant increase in films that were annealed to temperatures in the range of 1015 to 1050°C. In addition, the correlation between the magnitude of χ xxxx (3) with both the maximum value of the linear absorbance gradient and the residual homogeneous strain in the overlayer suggests that variations in the crystalline content of the film and the bonding distance between the Ga and N atoms are primary factors in determining the third-order nonlinearity in GaN. 相似文献
65.
Tai Li Wei Luo Shangfeng Liu Jiajia Yang Renchun Tao Ye Yuan Zhaoying Chen Jinlin Wang Tao Wang Xin Rong Duo Li Zhen Huang Weiyun Wang Junjie Kang Xinqiang Wang 《Advanced functional materials》2023,33(3):2208171
AlGaN-based ultraviolet-B light-emitting diodes (UVB-LEDs) exhibit great potential in phototherapy, vitamin D3 synthesis promotion, plant growth regulation, and so on. However, subjected to the excess compressive strain induced by the large lattice mismatch between multiple quantum wells (MQWs) and AlN, UVB-LEDs that simultaneously satisfy the requirements of high light output power (LOP), low working voltage, and excellent stability are rarely reported. Here, a substrate-dominated strain-modulation strategy is proposed. By precisely manipulating the strain in AlN grown on nano-patterned sapphire substrate (NPSS) to a slightly tensile one, the compressive strain in the following Al0.55Ga0.45N underlayer and Al0.28Ga0.72N/Al0.45Ga0.55N MQWs is successfully suppressed. As a result, an outstanding UVB-LED with a peak wavelength at 303.6 nm is achieved. The 20 × 20 mil2 UVB-LED chip shows a wall-plug efficiency (WPE) of 3.27% under a forward current of 20 mA and a high LOP of 57.2 mW with an extremely low voltage of 5.87 V under a forward current of 800 mA. It is more exciting that the LOP degradation is as low as 17% after 1000 h operation under a forward current density of 75 A cm−2, showing excellent stability. The here-developed UVB-LED, with a high LOP and excellent reliability, will definitely promote the applications of AlGaN-based UVB-LEDs. 相似文献
66.
Xiaobin Zou Haikuan Liang Yan Li Yichao Zou Fei Tian Yong Sun Chengxin Wang 《Advanced functional materials》2023,33(18):2213807
Following logic in the silicon semiconductor industry, the existence of native oxide and suitable fabrication technology is essential for 2D semiconductors in planar integronics, which are surface-sensitive to typical coating technologies. To date, very few types of integronics are found to possess this feature. Herein, the 2D Bi2O2Te developed recently is reported to possess large-area synthesis and controllable thermal oxidation behavior toward single-crystal native oxides. This shows that surface-adsorbed oxygen atoms are inclined to penetrate across [Bi2O2]n2n+ layers and bond with the underlying [Te]n2n− at elevated temperatures, transforming directly into [TeO4]n2n− with the basic architecture remaining stable. The oxide can be adjusted to form in an accurate layer-by-layer manner with a low-stress sharp interface. The native oxide Bi2TeO6 layer (bandgap of ≈2.9 eV) exhibits visible-light transparency and is compatible with wet-chemical selective etching technology. These advances demonstrate the potential of Bi2O2Te in planar-integrated functional nanoelectronics such as tunnel junction devices, field-effect transistors, and memristors. 相似文献
67.
Yubao Li Jingchao Xiao Xinqi Cao Zhiwei Gu Wei Zhang 《Advanced functional materials》2023,33(17):2213385
Here an IR-heating chemical vapor deposition (CVD) approach enabling fast 2D-growth of WSe2 thin films is reported, and the great potential of metal contact doping in building CVD-grown WSe2-based lateral homojunction is demonstrated by contacting with TiN/Ni metals in favor of holes/electrons injection. Shortening nanosheet channel to ≈2 µm leads to pronounced enhancement in the performance of diode. The fabricated WSe2-based diode exhibits high rectification ratios without the need of gate modulation and can work efficiently as photovoltaic cell, with maximum open circuit voltage reaching up to 620 mV and a high power conversion efficiency over 15%, empowering it as superb self-powered photodetector for visible to near-infrared lights, with photoresponsivity over 0.5 A W−1 and a fast photoresponse speed of 10 µs under 520 nm illumination. It is of practical significance to achieve well-performed photovoltaic devices with CVD-grown WSe2 using fab-friendly metals and simple processing, which will help pave the way toward future mass production of optoelectronic chips. 相似文献
68.
Xiaohui Lin Long Chen Chenglin He Yiliu Wang Xu Li Weiqi Dang Kun He Ying Huangfu Dan Wu Bei Zhao Bo Li Jia Li Xidong Duan 《Advanced functional materials》2023,33(1):2210278
Single crystal metal halide perovskites thin films are considered to be a promising optical, optoelectronic materials with extraordinary performance due to their low defect densities. However, it is still difficult to achieve large-scale perovskite single-crystal thin films (SCTFs) with tunable bandgap by vapor-phase deposition method. Herein, the synthesis of CsPbCl3(1–x)Br3x SCTFs with centimeter size (1 cm × 1 cm) via vapor-phase deposition is reported. The Br composition of CsPbCl3(1–x)Br3x SCTFs can be gradually tuned from x = 0 to x = 1, leading the corresponding bandgap to change from 2.29 to 2.91 eV. Additionally, an low-threshold (≈23.9 µJ cm−2) amplified spontaneous emission is achieved based on CsPbCl3(1–x)Br3x SCTFs at room temperature, and the wavelength is tuned from 432 to 547 nm by varying the Cl/Br ratio. Importantly, the high-quality CsPbCl3(1–x)Br3x SCTFs are ideal optical gain medium with high gain up to 1369.8 ± 101.2 cm−1. This study not only provides a versatile method to fabricate high quality CsPbCl3(1–x)Br3x SCTFs with different Cl/Br ratio, but also paves the way for further research of color-tunable perovskite lasing. 相似文献
69.
以六羰基钼和氧气为前驱体,通过等离子增强原子层沉积技术(PE-ALD)在硅基片上实现了α-MoO3薄膜的低温制备。利用X射线衍射仪、扫描电子显微镜、原子力显微镜、X射线光电子能谱仪等手段对薄膜的晶体结构、表面形貌及薄膜成分进行表征和分析。研究发现衬底温度和氧源脉冲时间对MoO3薄膜的晶体结构和表面形貌变化起关键作用。当衬底温度为170℃及以上时所制备的薄膜为α-MoO3;适当延长ALD单循环中的氧源脉冲时间有利于低温沉积沿(0k0)高度择优取向的MoO3薄膜。根据对不同厚度MoO3薄膜表面的原子力显微图片分析,MoO3薄膜为岛状生长模式。 相似文献
70.
Xianchun Peng Jie Sun Huan Liu Liang Li Qikun Wang Liang Wu Wei Guo Fanping Meng Li Chen Feng Huang Jichun Ye 《半导体学报》2022,43(2):79-85
AIN thin films were deposited on c-,a-and r-plane sapphire substrates by the magnetron sputtering technique.The in-fluence of high-temperature thermal annealing (HTTA) on the structural,optical properties as well as surface stoichiometry were comprehensively investigated.The significant narrowing of the (0002) diffraction peak to as low as 68 arcsec of AIN after HTTA implies a reduction of tilt component inside the AIN thin films,and consequently much-reduced dislocation densities.This is also supported by the appearance of E2(high) Raman peak and better Al-N stoichiometry after HTTA.Furthermore,the in-creased absorption edge after HTTA suggests a reduction of point defects acting as the absorption centers.It is concluded that HTTA is a universal post-treatment technique in improving the crystalline quality of sputtered AIN regardless of sapphire orienta-tion. 相似文献