电子束沉积技术生长WZO-TCO薄膜及其特性研究

采用电子束沉积技术生长w掺ZnO（WZO,ZnO：w）透明导电氧化物（TCO）薄膜（即WZO-TCO薄膜）并研究了衬底温度（100-350℃）对薄膜微观结构、表面形貌以及光电性能的影响。实验表明,随着衬底温度的升高,薄膜的晶体质量取得明显改善（从非晶化状态转变到结晶状态）,生长的WZO薄膜呈现C轴择优取向[即（002）...     

Thermally stable transparent conducting and highly infrared reflective Ga-doped ZnO thin films by metal organic chemical vapor deposition

Highly transparent conductive Ga-doped ZnO (GZO) thin films have been prepared on glass substrates by metal organic chemical vapor deposition. The effect of Ga doping on the structural, electrical and optical properties of GZO films has been systematically investigated. Under the optimum Ga doping concentration (∼4.9 at.%), c-axis textured GZO film with the lowest resistivity of 3.6 × 10⁻⁴ Ω cm and high visible transmittance of 90% has been achieved. The film also exhibits low transmittance (<1% at 2500 nm) and high reflectance (>70% at 2500 nm) to the infrared radiation. Furthermore, our developed GZO thin film can well retain the highly transparent conductive performance in oxidation ambient at elevated temperature (up to 500 °C).     

The influence of methanol addition during the film growth of SnO2 by atmospheric pressure chemical vapor deposition

Undoped tin oxide (SnO₂) thin films have been deposited in a stagnant point flow chemical vapor deposition reactor from a water/tin tetrachloride mixture. By adding methanol during the deposition process the film electrical properties change significantly: ten times more conductive SnO₂ films are obtained, with remarkably high mobility values of up to 55 cm²/V s. The investigations on the morphological and structural properties indicate that the main effect of methanol is the densification of the SnO₂ films, which probably causes the improvement in the electrical properties. In all conditions the nucleation and coalescence phases take place very early in the growth. Below 10 nm the films are already very conductive, which is very beneficial to applications that have strict requirements in terms of film transparency.     

Junction formation in chalcopyrite solar cells by sputtered wide gap compound semiconductors

In an effort to eliminate the CdS buffer layer and its costly preparation process we are considering sputtered buffer layers. In particular, we report in this contribution on the reactive sputtering of wide gap Zn(O,S) compound semiconductors and their application in solar cells with different types of chalcopyrite absorbers. While we were able to freely adjust the composition through the oxygen partial pressure, the structural and optical properties are superior when the composition is close to the ternary endpoints. Open circuit voltage and short circuit current density as a function of Sulphur content in the buffer show opposite trends. Working cells were achieved with low band gap as well as wide band gap absorbers, however, their performance is so far inferior to that of the standard stacks.     

Plasma-enhanced chemical vapor deposition of zinc oxide at atmospheric pressure and low temperature

The plasma-enhanced chemical vapor deposition of aluminum-doped zinc oxide has been demonstrated for the first time at 800 Torr and under 250 °C. A film resistivity of and a transparency of 95% from 375 to 2500 nm was obtained for deposition at 20-mTorr diethylzinc, 1.0 Torr CO₂, 799 Torr He, a TMAl/DEZn ratio of 1:100, RF power, and 225 °C. The average aluminum concentration in the ZnO film was . It was found that, while the growth rate did not change with substrate temperature, both the resistivity and optical absorption coefficient declined with increasing temperature.     

Transparent conductive oxide‐less back contact dye‐sensitized solar cells using cobalt electrolyte

Transparent conductive oxide‐less (TCO‐less) dye‐sensitized solar cells (DSSCs) have been fabricated and characterized using nanoporous TiO₂‐coated stainless steel metal mesh as flexible photoanode and cobalt bipyridyl complex (Co(bpy))‐based one electron redox shuttle electrolyte. Attempts have been made towards enhancing the efficiency of TCO‐less DSSCs to match with their TCO‐based DSSC counterparts. It has been found that surface protection of metal mesh is highly required for enhancing the efficiency of TCO‐less DSSCs specially using cobalt electrolytes as confirmed by dark current–voltage characteristics. Photocurrent action spectra clearly reveal that TCO‐based DSSCs using (Co(bpy)) electrolyte exhibits photon harvesting (incident photon to current conversion efficiency (IPCE) 52%) in the 370–450 nm wavelength region as compared to photon harvesting at peak absorption of the dye (IPCE 56% at 550 nm), which is almost the same (IPCE 47%) in the 400–610 nm wavelength region for TCO‐less DSSCs. Under similar experimental conditions, replacing indoline dye D‐205 to porphyrin‐based dye YD2‐o‐C8 led to the enhancement in the photoconversion efficiency from 3.33% to 4.84% under simulated solar irradiation. Copyright © 2014 John Wiley & Sons, Ltd.     

面向修复的计算技术分析

面向修复计算把硬件故障、软件错误和操作员失误当作不可避免的事实,研究的是面对事实的处理技术。它着眼于通过降低MTTR而提高系统的可用性,同时减少系统的总拥有成本。该文介绍了面向修复计算的目的及定义,并从认知心理学的角度讨论了人类出错的本质原因,最后从系统结构和操作系统的角度详细论述了面向修复计算的5个典型技术。     

Preparation of n-type semiconductor SnO2 thin films

We studied fluorine-doped tin oxide on a glass substrate at 350℃using an ultrasonic spray technique. Tin（Ⅱ） chloride dehydrate,ammonium fluoride dehydrate,ethanol and NaOH were used as the starting material, dopant source,solvent and stabilizer,respectively.The SnO₂:F thin films were deposited at 350℃and a pending time of 60 and 90 s.The as-grown films exhibit a hexagonal wurtzite structure and have（101） orientation.The G = 31.82 nm value of the grain size is attained from SnO₂:F film grown at 90 s,and the transmittance is greater than 80%in the visible region.The optical gap energy is found to measure 4.05 eV for the film prepared at 90 s, and the increase in the electrical conductivity of the film with the temperature of the sample is up to a maximum value of 265.58（Ω·cm）^-1,with the maximum activation energy value of the films being found to measure 22.85 meV,indicating that the films exhibit an n-type semiconducting nature.     

模块化UPS对客户TCO的影响

随着计算机和网络设备的普及,各行各业对交流电的可靠性要求越来越高,交流不间断电源系统(UPS)的应用也越来越广泛。同时,由于市场竞争力等因素的考虑,用户越来越关注UPS的TCO(Total Cost of Ownership)。本文重点探讨模块化UPS相对传统UPS在TCO方面的优势。     

Effect of metal-fingers/doped-ZnO transparent electrode on performance of GaN/InGaN solar cell

The effect of doped-ZnO transparent conductive oxide (TCO) with metal (Ag)-fingers contact on GaN/InGaN solar cell is investigated through numerical simulations. An optical and electrical analysis of different dopant elements (such as B, Al, Ga, In and Sn) with ZnO as a top TCO layer is studied. A comparative analysis of metal square pad electrode, metal grid pattern electrode and metal-finger/ZnO type electrodes are taken into consideration to ensure the effect of anti-reflectivity by ZnO. The effect of thickness of ZnO and i-InGaN layer on performance of solar cell is also studied in detail. The proposed solar cell structure with Ag-fingers/ZnO:Al as top contact electrode shows interesting device characteristics compared to other dopants and metal top electrodes. The device achieves open circuit voltage~2.525 V, short circuit current~4.256 mA/cm², fill factor~87.86% and efficiency~9.22% under 1 Sun, air mass 1.5 global illumination.