Optical and Electrical Properties of TixSi1‐xOy Films

Ti_xSi_1xO_y (TSO) thin films are fabricated using plasma‐enhanced atomic layer deposition. The Ti content in the TSO films is controlled by adjusting the sub‐cycle ratio of TiO₂ and SiO₂. The refractive indices of SiO₂ and TiO₂ are 1.4 and 2.4, respectively. Hence, tailoring of the refractivity indices from 1.4 to 2.4 is feasible. The controllability of the refractive index and film thickness enables application of an antireflection coating layer to TSO films for use as a thin film solar cell. The TSO coating layer on an Si wafer dramatically reduces reflectivity compared to a bare Si wafer. In the measurement of the current‐voltage characteristics, a nonlinear coefficient of 13.6 is obtained in the TSO films.     

Fabrication and electrical characteristics of ultrathin (HfO2)x(SiO2)1−x films by surface sol-gel method and reaction-anneal treatment

Hafnium oxide (HfO₂) films were deposited on Si substrates with a pre-grown oxide layer using hafnium chloride (HfCl₄) source by surface sol-gel process, then ultrathin (HfO₂)_x(SiO₂)_1−x films were fabricated due to the reaction of SiO₂ layer with HfO₂ under the appropriate reaction-anneal treatment. The observation of high-resolution transmission electron microscopy indicates that the ultrathin films show amorphous nature. X-ray photoelectron spectroscopy analyses reveal that surface sol-gel derived ultrathin films are Hf-Si-O alloy instead of HfO₂ and pre-grown SiO₂ layer, and the composition was Hf_0.52Si_0.48O₂ under 500 °C reaction-anneal. The lowest equivalent oxide thickness (EOT) value of 0.9 nm of film annealed at 500 °C has been obtained with small flatband voltage of −0.31 V. The experimental results indicate that a simple and feasible solution route to fabricate (HfO₂)_x(SiO₂)_1−x composite films has been developed by means of combination of surface sol-gel and reaction-anneal treatment.     

Tuning the spectrometric properties of white light by surface plasmon effect using Ag nanoparticles in a colour converting light-emitting diode

We report on the spectral tunability of white light by localized surface plasmon (LSP) effect in a colour converting hybrid device made of CdSe/ZnS quantum dots (QDs) integrated on InGaN/GaN blue light-emitting diodes (LEDs). Silver (Ag) nanoparticles (NPs) are mixed with QDs for generating LSP effect. When the plasmon absorption of Ag NPs is synchronized to the QW emission at 448 nm, the NPs selectively absorb the blue light and subsequently enhance the QD emission. Using this energy transfer scheme, the (x, y) chromaticity coordinates of the hybrid white LED was tuned from (0.32, 0.17) to (0.43, 0.26), and thereby generated warm white light emission with correlated colour temperature (CCT) around 1800 K. Moreover, a 47% enhancement in the external quantum efficiency (EQE) was realized.     

镁合金微弧氧化膜表面层与致密层界面组织的研究

研究镁合金微弧氧化膜的表面层与致密层界面处的组织形态。在磷酸盐碱性电解液(5～20g/LNaH2PO4,1～5g/LNaOH,5～8g/LKF,0.5～2g/LNa3C6H5O7,0.5～2g/LEDTA)中,以AZ91镁合金为基体制备出微弧氧化陶瓷薄膜,制备时采用恒电流控制模式,电流密度为10～30A/dm2。采用透射电镜(TEM)和扫描电镜(SEM)研究氧化薄膜界面及附近区域的微观结构。结果表明:微弧氧化膜的表面层靠近表面层与致密层界面处的组织以微晶和纳米晶为主,含有少量非晶态物质;微弧氧化膜的表面层与致密层界面处的组织以非晶态物质为主;微弧氧化膜的致密层靠近表面层与致密层界面处的组织为混晶组织,主要为MgO晶粒,少量为MgAlO4晶粒,并含有少量非晶态物质。     

High-performance inverted polymer solar cells with lead monoxide-modified indium tin oxides as the cathode

The photovoltaic stability of polymer solar cells (PSCs) can be greatly improved by adopting an inverted device structure. This paper reports high-performance inverted PSCs with lead monoxide (PbO)-modified indium tin oxide (ITO) as the cathodes. A thin PbO layer can effectively lower the work function of ITO from 4.5 to 3.8 eV. The optimal inverted PSCs with poly(3-hexylthiophene) (P3HT) as the donor and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) as the acceptor exhibited high photovoltaic performance: open-circuit voltage of 0.59 V, short-circuit current density of 10.8 mA cm⁻², fill factor of 0.632, and power conversion efficiency of 4.00% under simulated AM1.5G illumination (100 mW cm⁻²). The photovoltaic efficiency is significantly higher than that of the control inverted PSCs with unmodified ITO as the cathode. It is even better than that of the control PSCs with normal architecture, which have an optimal efficiency of 3.5%. The lowering in the work function by the PbO modification is attributed to the charge transfer between PbO and ITO, as evidenced by the X-ray photoelectron spectra.     

激光熔覆镍包纳米氧化铝

进行了2Cr13不锈钢表面激光熔覆镍包纳米氧化铝的实验。使用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、X射线能量色散谱仪(EDAX)、显微硬度仪等设备检测了涂层表面、横截面的显微组织和涂层的硬度、耐磨损等性能,分析了加入纳米氧化铝粒子后对涂层组织和性能的影响。研究结果表明,激光熔覆可获得致密的Fe-Ni(Cr)合金和Al2O3粒子复合涂层。其中,纳米氧化铝粒子弥散分布在微细合金晶粒之间,并与合金晶粒一起形成了胞状树枝晶结构。纳米氧化铝粒子的加入增加了基质金属的成核率,起到了细晶强化以及弥散强化的作用,使得复合涂层的机械性能大幅度提高。复合涂层的平均硬度为700HV0.2,比基体提高了1.5倍,耐磨损性能比淬火态基体提高了1.25倍。     

Electrical and surface composition properties of phosphorus implantation in Mg-doped GaN

Changes in electrical as well as surface composition such as chemical and electronic properties of Mg-doped p-type GaN by phosphorus implanting are systematically investigated using Hall effect and X-ray photoelectron spectroscopy (XPS) measurements. It is shown that p-type conductivity of Mg-doped GaN can be improved by implanting P atoms after a proper post-implantation annealing treatment, probably due to the reduction of self-compensation by P atoms substitution on N vacancy sites. XPS analysis is further found that the decrease of surface oxides and the shift of the surface Fermi level toward the valence band edge through P atoms introduced. These experimental results indicate that the P implantation is an effective method to improve p-type conductivity of Mg-doped GaN and reducing the surface barrier height, which can lead to a lower metal contact resistivity to p-type GaN.     

压电陶瓷银层附着力及其影响因素

通过瓷件表面粗糙度、瓷件的清洗方式、烧渗银温度和曲线等工艺过程的试验,研究了压电陶瓷银层附着力的影响因素。结果表明主要影响因素是瓷件表面粗糙度、清洁度以及银层烧结温度和曲线。在实际应用中,如果用天然石榴石金刚砂W40微粉细磨瓷件表面,再采用超声波清洗及煅烧,然后在780℃左右烧渗银,可使附着力达到最大,约1800N/cm2。     

Effects of substrate temperature on electrical and structural properties of copper thin films

This paper addresses the effects of substrate temperature on electrical and structural properties of dc magnetron sputter-deposited copper (Cu) thin films on p-type silicon. Copper films of 80 and 500 nm were deposited from Cu target in argon ambient gas pressure of 3.6 mTorr at different substrate temperatures ranging from room temperature to 250 °C. The electrical and structural properties of the Cu films were investigated by four-point probe and atomic force microscopy. Results from our experiment show that the increase in substrate temperature generally promotes the grain growth of the Cu films of both thicknesses. The RMS roughness as well as the lateral feature size increase with the substrate temperature, which is associated with the increase in the grain size. On the other hand, the resistivity for 80 nm Cu film decreases to less than 5 μΩ-cm at the substrate temperature of 100 °C, and further increase in the substrate temperature has not significantly decreased the film resistivity. For the 500 nm Cu films, the increase in the grain size with the substrate temperature does not conform to the film resistivity for these Cu films, which show no significant change over the substrate temperature range. Possible mechanisms of substrate-temperature-dependent microstructure formation of these Cu films are discussed in this paper, which explain the interrelationship of grain growth and film resistivity with elevated substrate temperature.