退火温度对a-C:H膜结构及摩擦学性能的影响

为研究环境温度对含氢无定形碳(a-C:H)膜结构和性能的影响,将a-C:H膜在大气环境中进行高温退火处理,并借助红外光谱、拉曼光谱、X射线光电子能谱、3D表面分析仪和球盘摩擦试验机等手段对退火前后a-C:H膜的结构、组成和性能进行了系统地考察.研究发现,在较低的退火温度下(300℃),a-C:H膜结构无明显变化,而其内应力降低,摩擦学性能显著提高;在400℃和500℃下退火,膜结构发生明显变化并伴随严重氧化,同时摩擦学性能降低甚至完全失效.结果表明,退火温度的选择对a-C:H膜的结构、组成及性能具有重要影响.     

氟化非晶碳薄膜的低频介电性质分析

研究了电子回旋共振等离子体技术沉积的氟化非晶碳(α-C：F)薄膜的低频(10^2～10^6Hz)介电性质。发现α-C：F薄膜的低频介电色散随源气体CHF3／C6H6的比例、微波入射功率而改变。结合薄膜键结构的红外分析,发现薄膜中C=C相对含量的增大是导致低频介电色散增强的原因,而C—F相对含量的增大则使低频介电色散减弱。     

氟化非晶碳膜结构的Raman和FTIR研究

利用反应射频磁控溅射法,以单晶Si片为衬底,在不同功率下制备了氟化非晶碳膜样品,并进行了不同温度的退火处理。采用拉曼光谱、傅里叶变换红外光谱和原子力显微镜对样品的结构进行了表征。通过谱线Lorentzian分峰拟合方法,分析比较了不同功率下制备的氟化非晶碳膜sp杂化结构,得到了薄膜生长过程功率控制与结构的关系,功率增大、退火温度升高,膜内sp2相对含量增加。退火温度达到350℃时,薄膜中石墨结构明显增加。     

退火对PMN—PT系陶瓷电学性能的影响

研究了退火对（１－ｘ）ＰＭＮ－ｘＰＴ（ｘ＝０－０．３４）陶瓷介电和压电性能的影响。分析了机理。结果表明，在ＰＴ含量较低时，退火使介电常数稍有提高；ＰＴ含量较高，接近准同型相界时，退火使介电常数有较大提高，尤其在居里温度附近，介电常数有显著提高。     

热循环退火对InAs/Si(211)薄膜结构和电学性能的影响

InAs作为III-V族化合物半导体材料,可以应用于磁阻和霍尔元器件、量子点激光器元件、太阳能电池和红外探测器元件等方面,具有广泛的研究和应用前景.本文以Si(211)为衬底,采用热壁外延(hot wall epitaxy,HWE)技术制备了InAs薄膜,研究热循环退火(thermal cycle annealing,TCA)次数对InAs/Si(211)薄膜结构及电学性能的影响.热壁外延制备InAs薄膜的衬底温度为400℃,生长时间为4 h,不同的热循环退火次数为2、4、6、8、10.X射线衍射(XRD)测试表明:利用HWE技术在Si(211)衬底表面成功制备了闪锌矿结构的InAs薄膜,且沿(111)取向择优生长;TCA能够明显增强Si(211)衬底表面生长的InAs薄膜的择优取向.扫描电子显微镜(SEM)及原子力显微镜(AFM)测试分析表明:随着TCA次数增加到6次,InAs/Si(211)薄膜表面由于晶粒细化作用变得均匀平整,表面粗糙度从69.63 nm降低到56.43 nm,此时霍尔迁移率达到2.67×10~3cm~2/(V·s);过多的退火次数(≥8次)又会使薄膜表面的晶粒过大、缺陷增多,导致薄膜性能下降.     

Ag掺杂非晶碳膜结构、力学与电学行为研究

采用反应磁控溅射技术, 通过改变溅射靶电流实现了不同Ag掺杂含量0.7at%~41.4at%非晶碳膜(a-C:Ag)的可控制备, 并系统研究了Ag含量对薄膜组分、结构、机械特性的影响规律, 以及薄膜的电学特性。结果表明: 当Ag含量在0.7at%~1.2at%时, Ag原子固溶于非晶碳基质; 当Ag含量在13.0at%~41.4at%范围, 薄膜中出现尺寸约为6 nm的Ag纳米晶。随着Ag含量增加, 碳网络结构的sp ²团簇尺寸增大, 结构无序度降低。应力测试表明, 在低Ag含量范围, Ag原子固溶于碳膜网络结构中, 起到枢纽作用, 促进碳网络结构键长、键角畸变弛豫, 从而降低薄膜应力。随着Ag含量增加, 部分Ag原子将形成Ag纳米晶粒, 薄膜通过Ag纳米晶与非晶碳界面处的滑移以及扩散作用释放过高的畸变能降低应力。Ag含量为37.8at%时, 在11.6 K附近, 薄膜出现金属-半导体特性转变。而Ag含量为41.4at%的薄膜, 在2~400 K测试温度范围内, 均表现为半导体特性, 其中在164~400 K范围内, 薄膜表现出典型的热激活导电机制。     

Cu掺杂非晶碳薄膜的电学性能及其载流子输运行为

以Cu-C拼接靶为靶材,用高功率脉冲磁控溅射制备出4种Cu含量(原子分数)低于10%的Cu掺杂非晶碳(a-C:Cu)薄膜,研究了Cu含量对a-C:Cu薄膜组分结构、电学性能以及载流子输运行为的影响。结果表明：随着非晶碳中Cu含量的提高,a-C:Cu薄膜中sp²-C的含量提高、团簇尺寸增大、薄膜电阻率、透过率和光学带隙均减小,费米能级向价带偏移。Cu含量为2.77%和3.88%的样品在150～250 K的载流子输运机制为Mott型三维变程跳跃传导,在250～350 K则为热激活传导;而Cu含量(原子分数)为5.4%和7.28%的样品在150～350 K均为Mott型三维变程跳跃传导。掺入Cu,可控制非晶碳薄膜的光学和电学性能。     

功率和温度对a-C:F:H膜表面形貌和结构的影响

分析薄膜的表面形貌对其生长机理和光学性质研究有着十分重要的作用。本文使用CF4和CH4为源气体，利用射频等离子体增强化学气相沉积（RF—PECVD）法在不同射频功率和沉积温度下制备了掺氟氢化无定形碳（a—C：F：H）薄膜，并在N2气氛中进行了不同温度的退火处理。用原子力显微镜（AFM）和扫描电子显微镜（SEM）观察了薄膜表面形貌，发现低功率下沉积的薄膜表面均匀性好、缺陷少；在低温下沉积的薄膜表面光滑，而高温下粗糙；真空低温退火可使薄膜表面形貌得到改善，但薄膜内空洞增加，退火温度过高，薄膜的结构发生变化，且在薄膜表面发生皲裂现象。用Raman光谱对薄膜内的结构变化进行了进一步的分析。     

退火温度对铜铟镓硒薄膜电学性能的影响

使用磁控溅射铜铟镓硒(CuIn1-xGaxSe2,CIGS)四元陶瓷靶材制备沉积态预制膜,在240-550℃对预制膜进行退火处理,着重研究了退火温度对薄膜电学性能(载流子浓度及迁移率)的影响。结果表明:退火温度低于270℃时薄膜中存在CuSe低电阻相,CIGS薄膜的载流子浓度在1017-1019cm-3,迁移率在0.1 cm2·V-1·s-1左右,不适于作为太阳电池的吸收层;当退火温度高于410℃时薄膜中不存在CuSe相,薄膜具有10 cm2·V-1·s-1左右的较高迁移率,载流子浓度在1014-1017cm-3;退火温度高于410℃时,随着退火温度的升高薄膜晶粒长大,结晶性增强,此时薄膜内部缺陷减少,载流子浓度升高;对于用作太阳电池吸收层的CIGS,从载流子浓度及迁移率的角度评判,合适的退火温度区间为450-550℃。     

Annealing effects on structural and electrical properties of fluorinated amorphous carbon films deposited by plasma enhanced chemical vapor deposition

The annealing effects on the structural and electrical properties of fluorinated amorphous carbon (a-C:F) thin films prepared from C₆F₆ and Ar plasma are investigated in a N₂ environment at 200 mTorr. The a-C:F films deposited at room temperature are thermally stable up to 250 °C, but as the annealing temperature is increased beyond 300 °C, the fluorine incorporation in the film is reduced, and the degree of crosslinking and graphitization in the film appears to be enhanced. At the annealing temperature of 250 °C, the chemical bond structures of the film are unchanged noticeably, but the interface trapped charges between the film and the silicon substrate are reduced significantly. The increased annealing temperature contributes the decrease of both the interface charges and the effective charge density in the a-C:F film. Higher self-bias voltage is shown to reduce the charge density in the film.     

Effects of ZnO addition on electrical and structural properties of amorphous SnO2 thin films

Amorphous Zn–Sn–O (ZTO) thin films with relative Zn contents (= [at.% Zn]/([at.% Zn] + [at.% Sn])) of 0, 0.08 and 0.27 were fabricated by co-sputtering of SnO₂ and ZnO targets at room temperature. Changes in structural, electrical and optical properties together with electron transport properties were examined upon post-annealing treatment in the temperature range from 200 to 600 °C in vacuum and in air. Characterization by XRD showed that an amorphous ZTO thin film crystallized at higher temperatures with increasing Zn content. Crystallized ZTO films with a relative Zn content of 0.27 might not contain a single SnO₂ phase which is observed in the films of the other compositions. Amorphous ZTO films showed decreasing electrical resistivities with increasing annealing temperature, having a minimum value of 1 × 10^− 3 Ω cm. Upon crystallization, the resistivities increased drastically, which was attributed to poor crystallinity of the crystallized films. All the ZTO films were found to be degenerate semiconductors with non-parabolic conduction bands having effective masses varying from 0.15 to 0.3 in the carrier concentration range of 6 × 10¹⁸ to 2 × 10²⁰ cm^− 3. As for a ZTO film with a relative Zn content of 0.27, the degree of non-parabolicity was much lower compared with films of the other compositions, leading to a relatively stable mobility over a wide range of carrier concentration.     

The structural and electrical properties of Metglas and amorphous metal films

We prepared non-alloyed, alloyed and gas-doped metal films by vapour quenching under ultrahigh vacuum conditions in order to find non-crystalline phases. Of the metals investigated (titanium, zirconium, vanadium, niobium, chromium, molybdenum, nickel, platinum, cobalt, copper, tungsten and tantalum such as TaNi, TaCo, WN, TaAr and TaN exhibited a non-crystalline phase which we call metglas because of its structural similarity to bulk Metglas®. TaNi and TaN films exhibited in addition a non-crystalline structure which we call solid-amorphous. The criteria for the characterization of the metglas and solid-amorphous structure are given.     

Effects of annealing temperature on the optical, bonding, structural and electrical properties of nitrogenated amorphous carbon thin films grown by surface wave microwave plasma chemical vapor deposition

We have studied the effects of annealing temperature (AT) on the properties of nitrogenated amorphous carbon (a-C:N) films grown at room temperature (RT) on quartz substrates by surface wave microwave plasma chemical vapor deposition (SWMP-CVD) using camphor alcohol gas as carbon plasma sources. The thickness, optical, bonding, structural and electrical properties of the as-grown (RT) and anneal-treated in range from 100 to 500°C of a-C:N films were measured and compared. The film thickness is decreased rapidly with increasing AT above 350°C. The wide range of optical absorption characteristics is observed depending on the AT. The optical band gap of as-grown a-C:N films is approximately 2.8 eV, gradually decreased to 2.5 eV for the films anneal-treated at 300°C and beyond that it decreased rapidly up to 0.9 eV at 500°C . Visible-Raman Spectroscopy (Raman) revealed the amorphous structure of as-grown a-C:N films and, the growth of nanocrystallinity of a-C:N films upon increase of AT. Raman and Fourier transform infrared spectroscopy (FTIR) analyses respectively shown the structural and composition of the films can be tuned by optimizing the AT. The change of optical, bonding, structural and electrical properties of SWMP-CVD grown a-C:N films with higher AT was attributed due to the fundamental changes in the bonding and band structure of the a-C:N films.     

Effects of hydrogen annealing on the structural, optical and electrical properties of indium-doped zinc oxide films

Indium-doped zinc oxide (IZO) films were fabricated by radio-frequency magnetron sputtering. The effects of hydrogen annealing on the structural, optical and electrical properties of the IZO films were investigated. The hydrogen annealing may deteriorate the crystallinity of the films. The surfaces of the films would be damaged when the annealing temperature was higher than 350 °C. After the annealing, the surface roughness of the films would decrease, and high transparency of 80–90% in the visible and near-infrared wavelength would be kept. Meanwhile, the resistivity decreased from 1.25 × 10⁻³ Ωcm of the deposited films to 6.70 × 10⁻⁴ Ωcm of the annealed films. The work function of the IZO films may be modulated between 4.6 and 4.98 eV by varying the hydrogen annealing temperature and duration.     

Effect of nitrogen addition on the properties and thermal stability of fluorinated amorphous carbon films

Continuous fluorinated amorphous carbon (a-C : F) films doped with nitrogen (a-C : F : N) were deposited by plasma enhanced chemical vapor deposition using CF₄ and C₂H₂ gases as precursors with the addition of N₂ gas. The surface morphologies, chemical compositions, deposition rates, thermal stability and mechanical properties of these films varied with the deposition parameters, including CF₄ and N₂ feed gas concentrations, processing pressure, plasma power and substrate temperature. With increasing N₂ feed gas concentration, the nitrogen content of the a-C : F : N films increased to about 6 at.% and contributed to higher mechanical properties. After thermal annealing, the a-C : F films with higher fluorine contents exhibited more obvious fluorine release and extensive film thickness shrinkage, whereas the a-C : F : N films with higher contents of nitrogen doping yielded less composition variations, smaller thickness shrinkages, higher mechanical properties, and conclusively better thermal stability.     

ECR-CVD制备氟化非晶碳低k介质薄膜

采用电子回旋共振等离子体化学气相沉积(ECR-CVD)方法,以C4F8和CH4为源气体在不同气体流量比R(R=[CH4]/{[CH4] [C4F8]})条件下成功地沉积了氟化非晶碳(a-C:F)低介电常数(低k)材料.采用X光电子能谱和椭圆光谱方法分析了a-C:F薄膜的化学组分和光学性质.沉积的a-C:F薄膜介电常数约为2.1～2.4,热稳定性优于350℃.随着气体流量比的增大,沉积a-C:F薄膜中的碳含量增大,CF、CF2、CF3含量减少,C-C交链成分增加,从而使得π-π(*)吸收增强,并引起薄膜光学带隙下降.氮气气氛下350℃温度退火后应力释放引起a-C:F薄膜厚度变化,变化量小于4%.450℃温度退火后,由于热分解作用薄膜厚度变化量在30%左右.     

Enhancing the field emission properties of amorphous carbon films by thermal annealing

Polymer-like hydrogenated and nitrogenated amorphous carbon films (a-C:H:N) have been deposited on silicon and glass substrates using a Plasma Technology DP800 radio frequency plasma enhanced chemical vapour deposition system. This equipment was configured with an earthed water-cooled substrate table, allowing the carbon films to grow under low bias conditions yielding films with refractive indices of ∼1.5−1.7, and E₀₄ optical band-gaps of ∼3−4 eV. The field emission properties of these films have been studied using a sphere-to-plane anode–cathode configuration, and the dependence on annealing treatment investigated. A significant lowering of the emission threshold field has been measured after treating the films for 1800 s at 400°C. This has been correlated with a simultaneous study of the change in the films’ microstructural properties. We conclude that the changes commensurate with the onset of graphitization are beneficial for field emission, and that the associated improvements in the films’ mechanical stability will aid incorporation into large-area displays.