金刚石膜表面微结构红外增透性能研究

CVD金刚石是一种性能优异的红外光学窗口材料，但其在红外波段的理论透过率仅能实现约71%。通过表面亚波长结构设计可进一步增强CVD金刚石膜的光学透过性能。该研究首先通过理论模拟，建立了金刚石微结构特征与光学增透之间的定量关系。基于此为指导，探讨了在具有微结构硅片表面，采用MPCVD方法复制生长出具有微结构的金刚石自支撑光学级薄膜，用于提升金刚石膜在红外波段的透过率。采用扫描电镜（SEM）观察了原始硅片和金刚石表面及微结构形貌，通过拉曼散射光谱评估了金刚石的生长质量及形核层影响，采用红外光谱仪测试了金刚石红外透过率。结果显示，单面构筑微结构后，金刚石膜在8~12 μm波段的透过率可从70%提升至76%，说明表面微结构能显著提升金刚石膜的光学透过性能。非金刚石形核层以及表面微结构的完整性不足可能是导致实验结果与理论模拟结果具有一定偏差的主要原因。     

金刚石薄膜的红外吸收谱研究

研究了热丝CVD金刚石薄膜的红外反射吸收谱,讨论了金刚石薄膜中H、N等杂质和晶粒晶型、晶粒尺度对膜红外透过率的影响。     

类金刚石薄膜的结构和红外光学性能研究

本文用辉光放电等离子体化学气相沉积(PCVD)法在Si、Ge玻璃等基片上制备出品质较好的类金刚石薄膜。首先,用拉曼光谱和红外吸收谱研究了所制备薄膜的结构,并且研究了制备膜的光吸收和光学带隙,然后,研究了沉积有类金刚石膜Si,Ge等基片的红外透过率。     

金刚石膜及类金刚石膜的光学应用研究进展

金刚石膜及类金刚石(DLC)膜由于具有宽光谱透过率高、硬度高、摩擦系数小、化学稳定性好等优点,可以作为多种光学材料如硅、锗、玻璃、硫化锌、MgF2,HgCdTe,KCl等的增透/保护膜,起到抗磨损、抗腐蚀、抗潮解和抗氧化的作用.金刚石膜及类金刚石膜已被应用于太阳能硅电池、高功率CO2激光器窗口、潜望镜红外(IR)窗口、飞机前视红外窗口、导弹头罩窗口和宇航探测器等.总结了这一方面的应用和研究进展,展示了金刚石膜及类金刚石膜巨大的优越性与广阔的应用前景.     

宽波段窗口材料透明尖晶石的透过性能

透明尖晶石陶瓷(TMAC)材料具有耐高温、耐腐蚀、较高的硬度和机械强度等优点,透过波段从紫外、可见、中波红外到微波,是性能优异的宽波段窗口材料,能够满足不断发展的光电系统对窗口材料的多重要求,且有广阔的应用前景。对采用热压烧结结合热等静压工艺制备出的TMAC材料进行了透过性能研究,分别对可见和红外波段镀制了增透膜,测试了不同入射角的红外透过率,并根据入射角的不同镀制了增透膜,测试了镀制金刚石膜后的透过率,并对毫米波波段的透过率做了初步测试和仿真,分析了不足和未来的研究方向。     

CVD金刚石的红外增透和抗氧化研究

CVD金刚石具有一系列优异的性能,红外透过率高、吸收系数低,抗热冲击、耐磨损能力强,是理想的长波红外（8μm～12μm）高速飞行器窗口和头罩材料。但是,CVD金刚石的高温氧化现象严重损害了其红外透过率。因此,CVD金刚石的红外增透、抗氧化就成为大家关注的焦点。这里介绍了目前提高CVD金刚石红外透过率的主要途径和研究进展。     

脉冲激光沉积类金刚石膜红外增透技术研究

针对传统方法制备类金刚石(DLC)膜存在的3～5μm波段红外透过率低这一难题,采用飞秒脉冲激光沉积(PLD)法在红外材料硅基底上镀制DLC膜.重点考查了靶材与基片的间距、背景气压、激光单脉冲能量、负偏压、温度以及掺硅量等工艺参数对其透过率的影响,经过大量的实验与优化分析,总结出一套有效的脉冲激光沉积DLC膜工艺来制备优良的光学保护增透膜.相比传统工艺,大大提高了3～5μm波段的平均红外透过率,在硅基底上单面镀制DLC膜的最高红外透过率达到了68.2%,与理论最高值的68.7%仅相差0.5%.     

射频功率对红外光学用类金刚石膜结构和性能的影响

利用射频等离子体增强化学气相沉积技术,以CH4为气源,在单晶锗基底上制备了具有红外增透效果的薄膜。Raman光谱分析表明,D峰和G峰分别位于1200~1450 cm-1和1500~1700 cm-1之间,说明薄膜具有典型的类金刚石的特征峰,可知镀制的薄膜是类金刚石膜。通过研究射频功率对类金刚石膜红外透过率以及硬度等性能的影响,分析了类金刚石膜的红外透过率和纳米硬度随着薄膜中sp3含量的增加而增大的原因,从而找出一种利用PECVD方法制备DLC膜的最佳工艺参数。     

不同取向金刚石薄膜的红外椭圆偏振光谱特性研究

采用红外椭圆偏振光谱仪对HFCVD方法所制备的不同取向金刚石薄膜的光学参数进行了测量.结果表明(001)取向金刚石薄膜具有较佳的光学质量,在红外波段基本是透明的.在2.5~12.5μm红外波长范围内,(001)取向金刚石膜的折射率和消光系数几乎不随波长的改变而变化,折射率为2.391,消光系数在10-5范围内;对于(111)取向金刚石膜,其折射率和消光系数随波长的改变有微小变化,折射率和消光系数都低于(001)取向膜.通过计算拟合得到(001)取向金刚石膜的介电常数为5.83,优于(111)取向膜.     

非晶金刚石与非晶碳化锗复合增透保护膜系的设计与实现

为了有效保护硫化锌等红外光学元件并提高其在工作波段的透过率,根据薄膜光学原理进行增透设计,从而获得膜系光学参数;采用射频磁控溅射技术制备非晶碳化锗薄膜,通过调整甲烷流速比调整薄膜的折射率,根据流速比和沉积时间控制膜厚,再用过滤阴极真空电弧技术制备非晶金刚石薄膜,分别改变衬底偏压和沉积时间控制薄膜的折射率和膜厚.利用光谱椭偏仪和台阶仪表征薄膜折射率和膜厚,通过小角X射线反射和X射线光电子谱测试非晶金刚石薄膜的密度和非晶碳化锗薄膜中的锗含量,使用纳米压痕仪和傅里叶红外透射谱仪确定薄膜的硬度和红外透过率.试验表明,非晶金刚石和非晶碳化锗薄膜的折射率分别与薄膜的密度和薄膜中的锗含量密切相关,非晶金刚石与非晶碳化锗复合膜系是硫化锌等红外光学元件性能优异的增透保护膜.     

CVD Diamond Sink Application in High Power 3D MCMs

As electronic packages become more compact, run at faster speeds and dissipate more heat, package designers need more effective thermal management materials. CVD diamond, because of its high thermal conductivity, low dielectric loss and its great mechanical strength, is an excellent material for three dimensional （319） multichip modules （MCMs） in the next generation compact high speed computers and high power microwave components. In this paper, we have synthesized a large area freestanding diamond films and substrates, and polished diamond substrates, which make MCMs diamond film sink becomes a reality.     

Electrical conductivity and photoluminescence of diamond films grown by downstream microwave plasma CVD

Electrical conductivity measurements and photoluminescence (PL) were used to study the effects that sample distance from the plasma during growth has on the carrier transport properties of undoped CVD diamond. The films were grown by downstream microwave plasma chemical vapor deposition at distances from 0.5 to 2.0 cm from the edge of plasma glow. Electrical conductivity measurements were performed between room temperature and 1000° C and then complimented with Raman spectroscopy and PL studies in an attempt to gain a better understanding of the CVD growth process and the resulting electrical and optical properties of the diamond films. Room temperature electrical conductivity was found to vary by over 5 orders of magnitude with increasing growth distance from the plasma, while only moderate changes were observed in the luminescence spectra.     

The effect of electron damage on silicon solar cells coated with diamond‐like carbon films

The unique properties of the diamond‐like carbon (a:DLC), such as high mechanical hardness and abrasive resistance, optical transparency in the visible and IR spectral regions and high thermal conductivity, provide this material with advantages over other types of protecting materials for solar cells. Furthermore, the a:DLC films are inert to corrosive gases and other corrosive agents. Resistance to radiation damage of the a:DLC films deposited on solar cells is very important for space application. In the study we investigate the effect of electron damage on silicon solar cells coated with a:DLC films. We measure the I – V characteristic and the spectral response and calculate the values of the seven parameters of the double exponential solar cell model (usually not investigated) as a function of electron fluence irradiation. In addition we obtain also the usual external parameters I_sc, V_oc, I_m, V_m, FF, and efficiency) of the solar cells. We investigate solar cells with and without anti‐reflecting coating coated with a:DLC films which were exposed to electron radiation. The main findings show that the solar cells with a:DLC films of thickness up to 500 nm degrade similarly to regular silicon cells exposed to electron irradiation. The degradation of the spectral response of the solar cell is mainly in the range of longer wavelengths and the irradiation affects the solar cell parameters (mainly the reverse saturation currents). Copyright © 2000 John Wiley & Sons, Ltd.     

Field-dependence of the area-density of 'cold' electron emission sites on broad-area CVD diamond films

A high area density of field-induced electron emission sites has been observed on broad-area (12 mm in diameter) CVD diamond films deposited on molybdenum substrates. Furthermore, it was found that the density increased with the electric field applied to the surface of the films. These findings indicate that the CVD diamond film has to be seen as a potentially favoured candidate among electronic materials for the development of new types of cold cathode electron source.<>     

Processing and properties of CVD diamond for thermal management

One of the many remarkable properties of diamond is its thermal conductivity, about five times that of copper and the highest of all known materials. The high thermal conductivity in combination with the relative ease of diamond film growth by chemical vapor deposition process makes the material suitable for many applications such as thermal management in high power electronic circuits. For thermal managements applications, various processing steps are needed for the diamond films, such as the metallization for reliable solder bonding, metallurgical processes for planarizing of the faceted growth surface and removal of fine-grained diamond regions with poor thermal conductivity. This paper will review the properties and processing of diamond films for thermal management applications.     

Influence of Bias-Enhanced Nucleation on Thermal Conductance Through Chemical Vapor Deposited Diamond Films

This work describes an experimental study of the cross-plane thermal conductance of plasma-enhanced chemical vapor deposited (PECVD) diamond films grown as a result of bias-enhanced nucleation (BEN). The diamond films are grown on silicon wafers using a two-step process in which a nucleation layer of amorphous or diamond like (DLC) carbon is first deposited on the silicon under the influence of a voltage bias. Then, conditions are adjusted to allow for polycrystalline diamond (PD) growth. The nucleation layer is essential for seeding diamond growth on smooth substrates and for optimizing PD properties such as grain size, orientation, transparency, adhesion, and roughness. A photoacoustic (PA) technique is employed to measure the thermal conductivities of and the thermal interface resistances between the layers in the diamond film structure. The influence of nucleation layers that are 70, 240, 400, and 650 nm thick on the thermal conductance of the diamond film structure is characterized. The thermal conductivity of the nucleation layer exhibits a thickness dependence for relatively thin layers. For each sample, the thermal conductivity of the PD is higher than 500 Wldrm^-1K^-1 (measurement sensitivity limit). A resistive network for the diamond film structure is developed. The resistance at the silicon/nucleation interface is less than 10^-9m²ldrKldrW^-1 (measurement sensitivity limit), which is of the order of theoretical predictions. The minimum diamond film structure resistance occurs when the nucleation layer is thinnest. When the nucleation layer is sufficiently thick, it begins to exhibit bulk behavior, and the resistance at the nucleation/PD interface dominates the thermal resistance of the diamond film structure.     

高质量CVD金刚石自支撑膜的连续激光损伤研究

利用HJ - 4型连续CO2 激光对金刚石膜进行了激光损伤阈值的研究,损伤后的金刚石膜用SEM和Raman进行了表征。研究结果表明,高质量CVD自支撑金刚石膜具有较高的 激光损伤阈值,金刚石膜抗连续激光损伤阈值的范围是在1. 15 ×106 ～2. 26 ×106W / cm2。金刚石膜激光损伤主要是由于热震损伤,其机制属于热- 力耦合机制。     

化学气相沉积光学级金刚石薄膜的研究进展

化学气相沉积（CVD））金刚石薄膜优异的光学性能在近几年得到了广泛的重视,关于它的研究也在近几年取得了较大的突破。综述了CVD金刚石薄膜的光学性能,着重从成核、生长和后期处理三个方面对光学级CVD金刚石薄膜的制备进行了讨论,并对今后的研究作了展望。