退火对含氮氟非晶碳膜结构及光学带隙的影响

采用射频等离子体增强化学气相沉积法,在不同条件下制备了含氮氟非晶碳膜,着重考察了退火温度对膜结构和光学带隙的影响. 研究发现：在350℃时,膜仍很稳定,当退火温度达到400℃时,其内各化学键的相对含量发生很大的改变. 膜的光学带隙随着退火温度的升高而增大,红外和拉曼光谱分析显示其原因是：退火使得膜内F的相对浓度降低,sp²相对含量升高,导致σ-σ^*带边态密度降低. 关键词： 含氮氟非晶碳膜 退火 光学带隙     

氟化非晶碳薄膜的光学带隙分析

研究了CHF3C6H6沉积的氟化非晶碳(αC∶F)薄膜的光学带隙.发现αC∶F薄膜光学带隙的大小取决于薄膜中C—F,CC的相对含量.这是由于CC形成的窄带隙π键和C—F形成的宽带隙σ键含量的相对变化,改变了带边态密度分布的结果.在微波功率为140—700W、沉积气压为01—10Pa、源气体CHF3∶C6H6流量比为1∶1—10∶1条件下沉积的αC∶F薄膜,光学带隙在176—398eV之间 关键词： 氟化非晶碳(αC∶F)薄膜 光学带隙 键结构     

立方氮化硼薄膜的光学带隙

用射频溅射法在p型Si(100)衬底上沉积立方氮化硼(c-BN)薄膜,薄膜的成分由傅里叶变换红外谱标识,用紫外-可见分光光度计测量了c-BN薄膜的反射光谱,利用K-K(Kramers-Kroning)关系从反射谱计算出c-BN薄膜的光吸收系数,进而确定c-BN薄膜的光学带隙.对于立方相含量为55.4%的c-BN薄膜,光学带隙为5.38eV. 关键词： 立方氮化硼薄膜 光学带隙 K-K关系     

电子回旋共振等离子体增强沉积氟化非晶碳薄膜的光学性质

用紫外可见光透射光谱(UV-VIS)并结合键结构的X射线光电子能谱(XPS)和红外谱(FTIR)分析,研究了电子回旋共振等离子体增强化学气相沉积法制备的氟化非晶碳薄膜的光吸收和光学带隙性质.在微波功率为140—700W、源气体CHF₃∶C₆H₆比例为1∶1—10∶1条件下沉积的薄膜,光学带隙在1.76—2.85eV之间.薄膜中氟的引入对吸收边和光学带隙产生较大的影响,吸收边随氟含量的提高而增大,光学带隙则主要取决于CF键的含量,是由于强电负 关键词： 氟化非晶碳薄膜 光吸收与光学带隙 电子回旋共振等离子体     

源气体对沉积的a-C∶F∶H薄膜结构的影响

采用微波电子回旋共振等离子体化学气相沉积(MWPECRCVD)方法,使用不同的源气体(CHF3CH4,CHF3C2H2,CHF3C6H6)体系制备了aC∶F∶H薄膜.由于CH4,C2H2,C6H6气体在等离子体中的分解反应不同导致了薄膜的沉积速率和结构上的差异.红外吸收谱的结果表明,用C6H6CHF3作为源气体沉积的薄膜中几乎不含H,而用C2H2CHF3所沉积的薄膜中的含氟量最高,其相应的CF振动峰位向高频方向偏移.薄膜的真空退火结果表明,aC∶F∶H薄膜的热稳定性除了取决于薄膜的CC键浓度外,还与CC键 关键词： 氟化非晶碳膜 电子回旋共振化学气相沉积 红外吸收光谱     

氧分压对溅射制备氧化镓薄膜结构及光学带隙的影响

在不同氧分压η(η=O2/[Ar+O2])实验条件下,通过直流反应溅射制备了氧化镓薄膜,然后在真空环境下进行高温再结晶热处理.用紫外-可见分光光度计(UV-Vis)研究了氧分压η对光学带隙Eg的影响.X射线衍射(XRD)和共聚焦拉曼散射光谱(Raman Scattering)分析显示:经900℃高温热处理后,薄膜呈结晶β相氧化镓,且晶粒尺寸随着氧分压的逐渐增加而变大.室温下由UV-Vis测试薄膜透过率并利用Tauc公式计算得到样品的光学带隙Eg在4.68—4.85 eV之间,且随氧分压η的逐渐增加而变大.     

溅射制备非晶氮化镓薄膜的光学性能

采用直流磁控溅射方法在不同的氩气-氮气（Ar-N₂）气氛中制备了非晶氮化镓（a-GaN）薄膜. X射线衍射分析（XRD）和拉曼光谱（Raman）表明薄膜具有非晶结构. 通过椭偏光谱（SE）得到薄膜的折射率和厚度都随着氩气分量的增多而增大. 紫外—可见光谱（UV-Vis）的测量得到,当氩气分量R,即Ar/（Ar+N₂）,为0%时,薄膜的光学带隙为3.90eV,比晶体GaN （c-GaN） 的较大,这主要是由非晶结构中原子无序性造成的;而当R关键词： 非晶氮化镓 溅射 光学带隙 带尾态     

微波输入功率引起a-C∶F薄膜交联结构的增强

使用C2H2和CHF3的混合气体,在改变微波功率的条件下,利用微波电子回旋共振等离子体增强化学气相沉积方法制备了氟化非晶碳薄膜(aC∶F).薄膜的傅里叶变换红外光谱分析结果表明:薄膜中的CC与C—F键含量的比值随功率的增加而相应地增大;借助于紫外可见光谱分析发现,薄膜的光学带隙随功率的增大而减小.由此推断微波输入功率的提高有助于增强薄膜的交联结构.aC∶F薄膜的交流电导与x射线光电子能谱进一步证实了这种增强效应 关键词： 氟化非晶碳薄膜 傅里叶变换红外光谱 x射线光电子能谱     

ECR-CVD法制备的a-C:F:H薄膜在N2气氛中的热退火研究

改变CHF3CH4源气体流量比,使用微波电子回旋共振化学气相沉积方法(ECRCVD)制备了具有不同C—F键结构的aC:F:H薄膜,着重研究了退火对其结构的影响.结果显示薄膜的厚度及其光学带隙E04随退火温度的上升均呈现了不同程度的下降.借助于红外吸收光谱和所提出的热解模型解释了产生这种关系的结构上的根源. 关键词： 电子回旋共振化学气相沉积 红外吸收光谱 热退火 光学带隙     

94MeV Xe离子辐照引起的薄膜硅光学带隙变化研究

室温下,用94MeV的Xe离子辐照纳米晶和非晶硅薄膜以及单晶硅样品,辐照量分别为1.0×1011,1.0×1012和1.0×1013ions/cm2。所有样品均在室温下用UV/VIS/NIR光谱仪进行检测分析。通过对比研究了纳米晶、非晶、单晶硅样品的光学带隙随Xe离子辐照量的变化。结果表明,不同结构的硅材料中Xe离子辐照引起的光学带隙变化规律差异显著:随着Xe离子辐照量的增加,单晶硅的光学带隙基本不变,非晶硅薄膜的光学带隙由初始的约1.78eV逐渐减小到约1.54eV,而纳米晶硅薄膜的光学带隙则由初始的约1.50eV快速增大至约1.81eV,然后再减小至约1.67eV。对硅材料结构影响辐照效应的机理进行了初步探讨。     

Determination of the optical bandgap for diamond-like carbon films obtained by laser plasma deposition

We have obtained and analyzed the optical transmission spectra of diamond-like carbon films deposited on quartz substrates by pulsed laser deposition (λ = 1064 nm, τ = 20 nsec, q = 4.9·10⁸ W/cm²) under vacuum (p = 2.6·10⁻³ Pa). Based on the spectra obtained, we have estimated the size of the bandgap by the Tauc method, and also have studied the growth dynamics of the coatings formed. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 637–641, September–October, 2007.     

Fe掺杂氢化非晶碳薄膜制备及其热稳定性能

以H2、反式-2-丁烯（T2B）和二茂铁混合气体为工作气体,用金属有机等离子体增强化学气相沉积法（PECVD）制备了Fe掺杂氢化非晶碳（a-C:H:Fe）薄膜。使用X射线光电子能谱（XPS）对a-C:H:Fe薄膜成分进行了分析。使用台阶仪、场发射扫描电镜（FESEM）、热重分析和紫外可见分光光度计（UV-VIS）,对比分析了a-C:H薄膜和a-C:H:Fe薄膜的沉积速率、表面形貌、热稳定性和光学带隙变化。研究表明：相同制备条件下,相比a-C:H薄膜,a-C:H:Fe薄膜的沉积速率高,表面颗粒小,容易碳化,光学带隙变窄。     

Excimer laser deposition of thin amorphous carbon films

A new carbon film deposition technique, based upon excimer laser vaporization of graphite in a flowing gas system has been developed. The low temperature vapor (LTV) technique alleviates high temperatures occurring in most other deposition methods. In this technique the UV laser ablation occurs in an inert flowing gas atmosphere. Atoms and molecules evaporated from graphite are cooled by gas entrainment before condensing on a substrate. The resulting films of amorphous carbon or hydrogenated amorphous carbon are free from strain. Measurement of the optical band gap of these films shows that E_g can be controlled by the hydrogen content of the carrier gas.     

氢化非晶硅薄膜的热导率研究

采用铂电极为加热电阻,研究了厚度为300—370nm等离子体化学气相沉积(PECVD)工艺制备的氢化非晶硅(a-Si：H)薄膜的热导率随衬底温度的变化规律.用光谱式椭偏仪拟合测量薄膜的厚度,得到了沉积速率随衬底温度变化规律,傅里叶红外(FTIR)表征了在KBr晶片衬底上制备的a-Si：H薄膜的红外光谱特性,SiH原子团键合模的震动对热量的吸收降低了薄膜热导率.从动力学角度分析了薄膜热导率随平均温度升高而增大的原因,并比较了声子传播和自由电子移动在a-Si：H薄膜热导率变化上的作用差异. 关键词： 非晶硅 热导率 薄膜 热能     

Photoluminescence of amorphous carbon films fabricated by layer—by—layer hydrogen plasma chemical annealing method

A method in which nanometre-thick film deposition was alternated with hydrogen plasma annealing (layer-by-layer method) was applied to fabricate hydrogenated amorphous carbon films in a conventional plasma-enhanced chemical vapour deposition system.It was found that the hydrogen plasma treatment could decrease the hydrogen concentration in the films and change the sp^2/sp^3 ratio to some extent by chemical etching.Blue photoluminescence was observed at room temperature,as a result of the reduction of sp^2 clusters in the films.     

Crystallization of hydrogenated amorphous silicon carbon films with laser and thermal annealing

The crystallization of silicon rich hydrogenated amorphous silicon carbon films prepared by Plasma Enhanced Chemical Vapor Deposition technique has been induced by excimer laser annealing as well as thermal annealing. The excimer laser energy density (E_d) and the annealing temperature were varied from 123 to 242 mJ/cm² and from 250 to 1200 °C respectively. The effects of the two crystallization processes on the structural properties and bonding configurations of the films have been studied. The main results are that for the laser annealed samples, cubic SiC crystallites are formed for E_d ≥ 188 mJ/cm², while for the thermal annealed samples, micro-crystallites SiC and polycrystalline hexagonal SiC are observed for the annealing temperature of 800 and 1200 °C respectively. The crystallinity degree has been found to improve with the increase in the laser energy density as well as with the increase in the annealing temperature.     

Fe掺杂氢化非晶碳薄膜制备及其热稳定性能

 以H₂、反式-2-丁烯（T₂B）和二茂铁混合气体为工作气体,用金属有机等离子体增强化学气相沉积法（PECVD）制备了Fe掺杂氢化非晶碳（a-C:H:Fe）薄膜。使用X射线光电子能谱（XPS）对a-C:H:Fe薄膜成分进行了分析。使用台阶仪、场发射扫描电镜（FESEM）、热重分析和紫外可见分光光度计（UV-VIS）,对比分析了a-C:H薄膜和a-C:H:Fe薄膜的沉积速率、表面形貌、热稳定性和光学带隙变化。研究表明：相同制备条件下,相比a-C:H薄膜,a-C:H:Fe薄膜的沉积速率高,表面颗粒小,容易碳化,光学带隙变窄。     

First-principles study of structural and opto-electronic characteristics of ultra-thin amorphous carbon films

Most amorphous carbon(a-C)applications require films with ultra-thin thicknesses;however,the electronic structure and opto-electronic characteristics of such films remain unclear so far.To address this issue,we developed a theoretical model based on the density functional theory and molecular dynamic simulations,in order to calculate the electronic structure and opto-electronic characteristics of the ultra-thin a-C films at different densities and temperatures.Temperature was found to have a weak influence over the resulting electronic structure and opto-electronic characteristics,whereas density had a significant influence on these aspects.The volume fraction of sp3 bonding increased with density,whereas that of sp2 bonding initially increased,reached a peak value of 2.52 g/cm³,and then decreased rapidly.Moreover,the extinction coefficients of the ultra-thin a-C films were found to be density-sensitive in the long-wavelength regime.This implies that switching the volume ratio of sp2 to sp3 bonding can effectively alter the transmittances of ultra-thin a-C films,and this can serve as a novel approach toward photonic memory applications.Nevertheless,the electrical resistivity of the ultra-thin a-C films appeared independent of temperature.This implicitly indicates that the electrical switching behavior of a-C films previously utilized for non-volatile storage applications is likely due to an electrically induced effect and not a purely thermal consequence.