Ge_xC_(1-x)非均匀增透保护膜系的设计和制备

用射频磁控反应溅射法 (RS)制备出 Gex C1-x薄膜 ,其折射率可以在 1 .7～ 4.0之间变化。设计出单层 Gex C1-x非均匀增透保护膜和含有 Gex C1-x非均匀膜的多层增透保护膜系 ,并在 Zn S基片上制备出 Gex C1-x单层非均匀增透保护膜。设计和实验结果表明 ,Zn S衬底上制备的非均匀膜实现了宽波段的增透 ,在 5 0 0 0～ 85 0 cm-1波数范围内 ,平均透过率从 6 7.1 9%提高到 78.70 % ,比未镀膜净增加 1 1 .5 1 %。     

红外增透保护膜系软件设计及应用

根据制备红外增透保护膜系需要 ,编制了一个红外增透保护膜系软件。该软件可以设计、计算多层红外均匀增透保护膜系和非均匀增透保护膜系 ,更有强大多层膜系结构分析功能 ,不仅可以对设计的膜系进行综合评价 ,而且能对制备的膜系结构进行分析。实验结果表明 ,该软件对膜系设计和为制备工艺的改进能提供良好的指导     

红外墙透保护膜系软件设计及应用

根据制备红外增透保护膜系需要,编制了一个红外增透保护膜系软件。该软件可以设计、计算多层红外均匀增透保护膜系和非均匀增透保护膜系,更有强大多层膜系结构分析功能,不仅可以对设计的膜系进行综合评价,而且能对制备的膜系结构进行分析。实验结果表明,该软件对膜系设计和为制备工艺的改进能提供良好的指导。     

GexC1—x薄膜在红外增透保护模系设计和制备中的应用

用磁控反应溅射（ＲＳ）法制备出ＧｅｘＣ１－ｘ薄膜,它的折射率可在１．６～４．０之间变化,设计出没厚度的ＧｅｘＣ１－ｘ均匀增透膜 非均匀增透膜系,并在ＺｎＳ基片上制备出ＧｅｘＣ１－ｘ均匀增膜系,设计结果表明,均匀膜系实现某－波段范围内增透,非均匀膜系能实现宽波段增透;当厚度增加时,均匀增透膜系的透过率曲线变得急剧振荡,非均匀膜系的透过率曲线变得更为平滑,且向长波段扩展,实现结果表明,在８～１１．５μ     

用于红外光学窗口的多层保护膜

采用GexC1-x（碳化锗）、BP（磷化硼）和-Si（非晶硅）作为高折射率材料,DLC（类金刚石）作为低折射率材料,在ZnS（硫化锌）、GaAs（砷化镓）、Ge（锗）等常用红外光学窗口表面研制了用于长波红外（8～12 m）波段的GexC1-x/DLC、BP/DLC及-Si/DLC系列多层保护膜。通过对比试验,研究了多层红外光学窗口保护膜的光学性能、显微硬度及海洋环境适应性。结合红外窗口及膜系材料特性,对试验结果进行了分析讨论。结果表明:GexC1-x/DLC多层红外保护膜具有最佳的光学性能,BP/DLC多层红外保护膜在海洋环境下具有最佳的保护效果。     

机载瞄准光学系统关键系设计研究

依据薄膜光学多膜膜系设计理论，利用菲涅尔系数矩阵和光学导纳矩阵的设计方法，完成机载瞄准光学系统关键膜系－红外窗口的增透保护膜和激光／电视分光膜－的膜系设计，计算结果满足相关的技术要求。     

机载瞄准光学系统关键膜系设计研究

依据薄膜光学多膜膜系设计理论,利用菲涅尔系数矩阵和光学导纳矩阵的计算方法,完成机载瞄准光学系统关键膜系——红外窗口的增透保护膜和激光／电视分光膜——的膜系设计,计算结果满足相关的技术要求。     

基于8-11μm红外窗口系统中减反射与保护膜的研制

随着现代军事空间技术的快速发展,对红外探测器的要求越来越高。同时,对红外光学元件的要求也越来越苛刻。主要研究了硫化锌(ZnS)基底表面减反与保护膜的制备技术,采用介质膜与硬膜复合方法,通过对不同材料的对比分析,最终选取碳化锗(Ge1-xCx)材料作为介质膜与DLC 类金刚石保护膜的过渡层。利用电子束与离子源辅助沉积技术制备介质膜;磁控溅射技术制备过渡层碳化锗;化学气相沉积技术制备DLC 类金刚石保护膜,解决了介质膜与类金刚石保护膜应力匹配的问题,并通过对多种沉积工艺的整合,得到了一套稳定的工艺制备流程。最终在硫化锌基底上制备出的减反射与保护膜平均透过率达到92%,硬度符合要求。     

脉冲激光沉积低内应力多层类金刚石膜

为解决类金刚石膜内应力极大的问题,利用很薄的岛状结构锗层与较厚的类金刚石层循环,设计并制备了具有低内应力的多层类金刚石膜。其中,类金刚石层为主要功能膜层,起到硬质保护和光学增透的作用;而锗层作为缓冲层,起到缓解纯类金刚石膜内应力过大的问题,同时由于锗层很薄,对整个膜层的机械性能和红外特性的影响很小。测试表明,制备的多层类金刚石膜内应力为2.14 GPa,比纯类金刚石膜降低了39%,通过了GJB2485-95《光学膜层通用规范》中的重摩擦测试;同时,其纳米硬度仍保持在47 GPa的高水平。该多层类金刚石膜可以作为实际应用的红外窗口保护膜。     

红外增透与保护膜技术的研究

采用电子束与离子辅助沉积技术,在氟化镁晶体材料上制备3．5～4．9μm增透与保护膜。经过实验,选取氧化钛与二氧化硅作为薄膜材料,并优化沉积工艺参数,尽可能减少吸收损失,对氟化镁基底实现有效的增透和保护。实验结果表明,镀膜后其单面剩余反射率由未镀膜时的2．5％减少到1．2％,并能承受湿热和雨淋测试。     

Morphological and electrical characterization of SixCryCzBv thin films

Si_xCr_yC_zB_v thin films with several compositions have been studied for integration of high precision resistors in 0.8 μm BICMOS technology. These resistors, integrated in the back-end of line, have the advantage to provide high level of integration and attractive electrical behavior in temperature, for analog devices. The film morphology and the structure have been investigated through transmission electron microscopy analysis and have been then related to the electrical properties on the base of the percolation theory. According to this theory, and in agreement with experimental results, negative thermal coefficient of resistance (TCR) has been obtained for samples with low Cr content, corresponding to a crystalline volume fraction below the percolation threshold.Samples with higher Cr content exhibit, instead, a variation of the TCR as a function of film thickness: negative TCR values are obtained for thickness lower than 5 nm, corresponding to a crystalline volume fraction below the percolation threshold; positive TCR are obtained for larger thickness, indicating the establishment of a continuous conductive path between the Cr rich grains. This property seems to be determinant in order to assure the possibility to obtain thin film resistors almost independent on the temperature.     

Current-voltage characteristics of GaAs p-i-n and n-i-n diodes

Using the same basic equations as Kazarinov et al.[2], but assuming that the product of the electron drift velocity and of the electron lifetime remains constant, we have derived a new formula for the forward d.c. current—voltage characteristic distinguished by the saturated voltage. We have shown that this formula can describe the measured characteristics of some GaAs p-i-n and n-i-n diodes.     

Pentacene/n-Si heterojunction diodes and photovoltaic devices investigated by I-V and C-V measurements

The forward and reverse current density-voltage (J-V) and capacitance-voltage (C-V) characteristics of pentacene/n⁻-silicon heterojunction diodes were investigated to clarify the carrier conduction mechanism at the organic/inorganic heterojunction. Current rectification characteristics of the pentacene/n⁻-Si junctions can be explained by a Schottky diode model with an interfacial layer. The diode parameters such as Schottky barrier height and ideality factor were estimated to be 0.79-1.0 eV and 2.4-2.7, respectively. The C-V analysis suggests that the depletion layer appears selectively in the n⁻-Si layer with a thickness of 1.47 μm from the junction with zero bias and the diffusion potential was estimated at 0.30 eV at the open-circuit condition. The present heterojunction allows the photovoltaic operation with power conversion efficiencies up to 0.044% with a simulated solar light exposure of 100 mW/cm².     

Traffic and /spl lambda/ grooming

The article gives an overview of traffic grooming and lambda grooming in multilayer networks, and discusses the advantages and drawbacks of these methods as well as applications and future alternative directions.     

Effect of BaCeO/sub 3/ and BaSnO/sub 3/ additives on microstructural development and critical current density of melt textured YBa/sub 2/Cu/sub 3/O/sub 7-x/

Improvement of superconducting properties, such as critical current density J/sub c/ and trapped magnetic field, of melt textured YBa/sub 2/Cu/sub 3/O/sub 7-x/ (Y123) require introducing of effective pinning sites, e.g., nonsuperconducting inclusions, twin boundaries and other defects. It has been shown that addition of small quantities of BaCeO/sub 3/ (<0.5 wt%) into Y123 results in an increase of the J/sub c/. However, higher cerium concentrations affect the solidification process and inhibit the growth of melt textured Y123 single crystals. In this study, the effect of BaCeO/sub 3/ additions on the growth and microstructural development of melt textured Y123 single crystals were investigated. The relationship between the solidification kinetics, microstructural development and superconducting properties of Y123 melt textured single crystals with cerium additives is discussed.     

Long-wavelength In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As large-area avalanche photodiodes and arrays

Large-area (500-/spl mu/m diameter) mesa-structure In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiodes (APDs) are reported. The dark current density was /spl sim/2.5/spl times/10/sup -2/ nA//spl mu/m/sup 2/ at 90% of breakdown; low surface leakage current density (/spl sim/4.2 pA//spl mu/m) was achieved with wet chemical etching and SiO/sub 2/ passivation. An 18 /spl times/ 18 APD array with uniform distributions of breakdown voltage, dark current, and multiplication gain has also been demonstrated. The APDs in the array achieved 3-dB bandwidth of /spl sim/8 GHz at low gain and a gain-bandwidth product of /spl sim/120 GHz.     

Comparison between Pt/TiO2/Pt and Pt/TaOX/TaOY/Pt based bipolar resistive switching devices

Nonvolatile memories have emerged in recent years and have become a leading candidate towards replacing dynamic and static random-access memory devices. In this article, the performances of TiO₂ and TaO₂ nonvolatile memristive devices were compared and the factors that make TaO₂ memristive devices better than TiO₂ memristive devices were studied. TaO₂ memristive devices have shown better endurance performances (10⁸ times more switching cycles) and faster switching speed (5 times) than TiO₂ memristive devices. Electroforming of TaO₂ memristive devices requires~4.5 times less energy than TiO₂ memristive devices of a similar size. The retention period of TaO₂ memristive devices is expected to exceed 10 years with sufficient experimental evidence. In addition to comparing device performances, this article also explains the differences in physical device structure, switching mechanism, and resistance switching performances of TiO₂ and TaO₂ memristive devices. This article summarizes the reasons that give TaO₂ memristive devices the advantage over TiO₂ memristive devices, in terms of electroformation, switching speed, and endurance.     

Annealing effect on physical and electrical characteristics of thin HfO2, HfSixOy and HfOyNz films on Si

We report the effect of annealing on electrical and physical characteristics of HfO₂, HfSi_xO_y and HfO_yN_z gate oxide films on Si. Having the largest thickness change of 0.3 nm after post deposition annealing (PDA), HfO_yN_z shows the lowest leakage current. It was found for both as-grown and annealed structures that Poole-Frenkel conduction is dominant at low field while Fowler-Nordheim tunneling in high field. Spectroscopic ellipsometry measurement revealed that the PDA process decreases the bandgap of the dielectric layers. We found that a decreasing of peak intensity in the middle HfO_yN_z layer as measured by Tof-SIMS may suggest the movement of N toward the interface region between the HfO_yN_z layer and the Si substrate during the annealing process.     

1/spl times/2 and 1/spl times/4 electrooptic switches

We describe the design, fabrication, and testing of two packaged electrooptic switches built from poled LiTaO/sub 3/ crystals. The 1/spl times/2 switch requires a driving voltage of 1200 V and exhibits insertion loss of 2.4 dB and crosstalk of -39.2 dB; the 1/spl times/4 switch exhibits insertion loss and crosstalk of 2.8 dB and -40.6 dB, respectively, and operates using a 1100-V voltage source. The maximum deflection time between the channels is 86 ns.