原子层沉积制备Al_2O_3薄膜的光学性能研究

研究了原子层沉积制备氧化铝薄膜的光学性能。以三甲基铝(TMA)和水为前聚体,分别在基板温度为250℃和300℃的K9和石英玻璃衬底上沉积了Al2O3光学薄膜。采用分光光度计,X射线光电子能谱(XPS),X射线衍射(XRD),原子力显微镜(AFM),扫描电子显微镜(SEM)等分析手段对薄膜的微结构、表面形貌和光学特性进行了研究。结果表明,原子层沉积法制备的Al2O3薄膜在退火前后均呈现无定形结构,元素成分接近化学计量比,其表面粗糙度小于1.2nm,聚集密度高于0.97,光学非均匀性优于1%。同时在中紫外到近红外均有很好的光学性能,适合作为中间折射率和低折射率材料在光学薄膜中得到应用。     

原子层沉积制备铱薄膜的特性研究

以乙酰丙酮铱[Ir(acac)3]和高纯氧为前驱体,采用原子层沉积(ALD)方法在基板温度为340℃的石英玻璃和硅基板上制备了金属铱薄膜。采用反射光谱测试仪、X射线电子能谱(XPS)、X射线衍射(XRD)、扫描电子显微镜(SEM)和原子力显微镜(AFM)等手段对不同厚度薄膜的微结构、表面形貌和光学性能进行了研究。结果表明,原子层沉积制备的Ir薄膜中元素纯度较高(大于95%),表面粗糙度低,并呈现多晶纳米颗粒。同时,Ir薄膜在紫外波段表现出较好的光学特性,可以用于制作Ir金属紫外光栅等光学器件。     

退火温度对原子层沉积法制备ZnMgO薄膜结构和光学性能的影响

针对目前关于退火温度对原子层沉积法(ALD)制备ZnMgO薄膜晶体结构和光学性质影响鲜有报道的现象,进行了相应的实验研究分析。采用ALD在石英衬底上制备ZnMgO合金薄膜,对制得的样品在空气中进行不同温度的退火处理。利用X射线多晶衍射仪(XRD)、光致发光谱(PL)和紫外可见(UV-Vis)吸收光谱测试,系统的分析了不同退火温度对ALD法制备ZnMgO薄膜晶体结构和光学性能的影响。XRD测试结果表明：退火温度为600 ℃时,薄膜的晶体质量得到改善,且(100)衍射峰的强度明显增强。结合PL和UV-Vis吸收光谱的测试分析得出：退火温度为600 ℃时,能明显促进薄膜中Mg组分的增加使薄膜的禁带宽度进一步增大。从而说明适当温度的退火处理可有效的改善ZnMgO薄膜的晶体质量及光学特性。     

光谱法确定离子束溅射Ta_2O_5/SiO_2薄膜的光学常数及其性能

采用双离子溅射的方法,在硅、石英基底上制备了单层Ta2O5、SiO2及双层Ta2O5/SiO2光学薄膜。结合Cauchy色散模型,利用石英基底上单层Ta2O5及双层Ta2O5/SiO2薄膜透射光谱曲线,采用改进的遗传单纯形混合算法,获得了Ta2O5和SiO2薄膜材料在400~700nm波段的光学常数。结果表明,理论分析值与实验测量值取得了很好的一致性,拟合出的单层Ta2O5薄膜折射率误差小于0.001,膜层厚度误差不超过1nm;双层Ta2O5/SiO2薄膜最大折射率误差小于0.004,最大厚度误差小于2.5nm。此外,还对400℃高温环境下双层Ta2O5/SiO2薄膜的微观结构、应力、表面形貌及光学性能变化进行了研究。     

金属氧化物薄膜在中波红外光谱区内光学常数色散特性

基于金属氧化物薄膜材料在中波红外波段应用的需求,研究了含水状态的TiO2、HfO2、Ta2O5和Y2O34种金属氧化物薄膜在中波红外波段内(2.5~5μm)光学常数的色散特性。利用电子束蒸发沉积技术,在超光滑的硅表面制备了4种氧化物薄膜,基于洛仑兹振子介电常数色散模型,通过透射率光谱反演计算了4种氧化物薄膜的光学常数。研究结果表明:4种氧化物均有少量的水分子、羟基,水含量从少到多的薄膜依次为TiO2、HfO2、Ta2O5和Y2O3,在远离水吸收的位置,消光系数从小到大的薄膜分别为TiO2、HfO2、Ta2O5和Y2O3;在电子束蒸发沉积工艺条件下,为了降低水的影响,TiO2和HfO2是中红外波段较为理想的金属氧化物薄膜材料。     

氧化法结合快速热处理制备VOx薄膜及其性质研究

采用磁控溅射法在单晶Si〈100〉基底上沉积金属钒(V)薄膜,在高纯氧环境下快速热处理制备具有相变特性的氧化钒(VOx)薄膜.利用X射线衍射仪、X射线光电子能谱和扫描电子显微镜对薄膜结晶结构、薄膜中V的价态与组分及表面微观形貌进行分析,应用四探针测试方法和太赫兹时域频谱技术对样品的电学和光学特性进行测试.结果表明:在一定范围的快速热处理保温温度和保温时间下,都可以制备出具有热致相变特性的氧化钒薄膜,相变前后薄膜的方块电阻变化超过两个数量级,薄膜成分主要由V2O5和VO2混合组成,薄膜中V整体价态不因热处理条件改变而不同.在快速热处理条件范围内,500℃ 25 s左右条件下(中温区)制备出的氧化钒薄膜相变特性最佳,并且对THz波有一定的调制作用.     

衬底温度对电子束沉积ZnSe薄膜性能影响研究

为了研究衬底温度对硒化锌薄膜微观结构和光学特性的影响,采用电子束蒸发技术在K9玻璃基底上制备了单层的硒化锌薄膜.通过研究薄膜的X射线衍射谱、透射光谱特性、表面形貌及粗糙度,分析了不同衬底温度下薄膜微观晶体结构和光学特性的变化规律.实验结果表明:在20～200℃的衬底温度范围内制备的ZnSe薄膜均为具有(111)晶面择优...     

生长温度对磁控溅射ZnO薄膜的结晶特性和光学性能的影响

采用反应射频磁控溅射方法，在Si (100) 基片上制备了具有高c轴择优取向的ZnO薄膜.利用 原子力显微镜、透射电子显微镜、X射线衍射分析、拉曼光谱等表征技术，研究了沉积温度 对ZnO薄膜的表面形貌、晶粒尺度、应力状态等结晶性能的影响；通过沉积温度对透射光谱 和光致荧光光谱的影响，探讨了ZnO薄膜的结晶特性与光学性能之间的关系.研究结果显示， 在室温至500℃的范围内，ZnO薄膜的晶粒尺寸随沉积温度的增加而增加，在沉积温度为500 ℃时达到最大；当沉积温度为750℃时，ZnO薄膜的晶粒尺度有所减小；在室温至750℃的范 围内，薄膜中ZnO晶粒与Si基体之间均存在着相对固定的外延关系；在沉积温度低于500℃时 ，制备的ZnO薄膜处于压应变状态，而750℃时沉积的薄膜表现为张应变状态.沉积温度的不 同导致ZnO薄膜的折射率、消光系数、光学禁带宽度以及光致荧光特性的变化，沉积温度对 紫外光致荧光特性起着决定性的作用.此外，探讨了影响薄膜近紫外光致荧光发射的可能因 素. 关键词： ZnO薄膜 表面形貌 微观结构 光学常数     

紫外Sc2O3薄膜的光学和结构性能表征及其激光作用下的损伤机理

利用电子束蒸发方法,在不同沉积温度 (50~350 ℃)下制备了Sc2O3薄膜。分别用分光光度计,小角掠入射X射线衍射仪和轮廓仪测试了薄膜样品的光谱、微结构和表面粗糙度信息,并用薄膜分析软件Essential Macleod计算了Sc2O3薄膜的折射率和消光系数。结果表明：随着沉积温度升高,Sc2O3薄膜结晶程度增强,晶粒尺寸增大,且较高的沉积温度有利于获得较高的折射率。最后用355 nm,8 ns的三倍频Nd:YAG激光器测试了其激光损伤阈值（LIDT）,最大值为2.6 J/cm2,且阈值与薄膜的消光系数、表面粗糙度、光学损耗均呈现相反的变化趋势。用光学显微镜和扫描电子显微镜表征了该薄膜的破坏形貌,详细分析了薄膜在不同激光能量作用下破坏的发展过程,以及Sc2O3薄膜在355 nm紫外激光作用下LIDT与制备工艺的关系,重点分析了355 nm激光作用下薄膜的破坏机理。     

沉积温度对硫化锌(ZnS)薄膜的结晶和光学特性影响研究

对不同温度下沉积的ZnS薄膜的结晶情况和光学特性进行了研究, 结果表明：沉积温度对ZnS薄膜的物理和光学特性有较大影响, 不同的温度沉积的ZnS薄膜具有不同的择优取向, 牢固度也大不相同; 不同沉积温度下, ZnS薄膜的光学常数也不尽相同. 温度为115 ℃和155 ℃时, ZnS薄膜的物理性能和光学性能较差, 不适合空间用光学薄膜的研制使用. 而190 ℃和230 ℃沉积温度下所得薄膜具有较好的物理和光学性能, 适合于不同要求的空间用薄膜器件的研制使用. 关键词： 硫化锌薄膜 沉积温度 表面形貌 光学常数     

Dielectric properties of polyacrylamide polymer films

Summary Polyacrylamide polymer films of thickness 4.15 μm were prepared by isothermal immersion technique. The dielectric capacitance and dielectric loss of the films were studied as functions of frequency and temperature in the range 100 Hz|10 MHz and (300|450)K, respectively. Two dielectric loss peaks were observed in the dielectric loss spectra and were identified as β and α peaks. The β peak was attributed to the reorientation of dipoles and the α-peak was attributed to the deformations accompanied by large changes in the directions or locations of the dipoles.     

多晶氧化物薄膜及复合膜系应力模型

基于膜层结构的弛豫现象,建立了一个多晶膜的应力演化模型,并通过线性组合给出了复合膜的生长应力模型。利用双光束基底曲率测量装置实时测量了电子束蒸发氧化铪、氧化硅多晶膜及其复合膜的应力演化过程,并对测量结果进行了拟合分析。     

Microwave magnetic properties of soft magnetic thin films

We review our works that focus on the microwave magnetic properties of metallic,ferrite and granular thin films.Soft magnetic material with large permeability and low energy loss in the GHz range is a challenge for the inforcom technologies.GHz magnetic properties of the soft magnetic thin films with in-plane anisotropy were investigated.It is found that several hundreds of permeability at the GHz frequency was achieved for Co100-xZrx and Co90Nb10 metallic thin films because of their high saturation magneti...     

Structural characterization and magnetoresistance of manganates thin films and Fe-doped manganates thin films

Perovskites thin films with the composition La_0.6Ca_0.4MnO₃ doped with 20% Fe, were prepared by pulsed reactive crossed beam laser ablation, where a synchronized reaction gas pulse interacts with the ablation plume. The films were grown on various substrates and the highest colossal magnetoresistance ratio (CMR) was detected by Hall measurements for films grown on LaAlO₃ (1 0 0), which was selected as substrate for further investigations.Several growth parameters, such as substrate temperature and target to substrate distance were varied to analyze their influence on the film properties.The structure of the deposited thin films was characterized by X-ray diffraction and atomic force microscope, while Rutherford backscattering (RBS) was used to determine the film stoichiometry. The electrical properties were determined by Hall effect measurements in a magnetic field of 0.51 T.These measurements reveal that the amplitude of the CMR ratio depends strongly on the substrate and that the oxygen content influences the temperature where the transition from semiconductor to metal is observed.     

The accuracies of photometric, polarimetric and ellipsometric methods for the optical constants of thin films

The inherent accuracies of various techniques for determining the optical constants of thin films have been assessed by computing the errors produced in n and k by known experimental errors in the optical functions being measured. The results are presented as arrays of error parallelograms in the n–k plane covering d/λ from 0.001 to 0.20 and θ from 5° to 85°.The largest regions of accuracy, in the form of annular quadrants, were obtained using the mixed photometric and polarimetric functions at small angles of incidence. Ellipsometry gives similar results at large angles of incidence but for photometry and for polarimetry the accurate regions were in the form of two lobes.The effects of errors in x and θ were also considered.     

Photon drag detection of 10 μm radiation in Bi thin-films evaporated on amorphous substrates

Summary We have observed IR detection signals with ns response in irradiated Bi thin films, which were evaporated at large angles with the substrate normal direction. At 10 μm radiation, these detectors show a voltage response with reversed sign compared to the visible-light response which is generated by a well-known thermoelectric effect. Other thin-film metallic detectors as Cr films operating with this effect do not show this sign inversion at 10 μm. We attribute the sign-reversed fast signal in bismuth to a transversal photon drag effect related to the interband transition induced by the 10 μm radiation.

---

Riassunto Noi abbiamo osservato una generazione di tensione prodotta ai capi di un film anisotropo di bismuto dall'assorbimento di radiazione a 10 μm. Questa risposta è veloce (ns) ed è differente dal normale segnale termovoltaico osservato in Bi e altri metalli (es. Cr) illuminati da luce visibile, sebbene tale segnale sia osservabile anche a 10 μm. Noi abbiamo attribuito questo segnale veloce ad un effetto di photo-drag trasverso dovuto a transizioni interbanda in microcristalli orientati da una evaporazione a forte angolo.

---

Резюме Мы наблюдаем сигналы детектирования инфракрасного излучения с наносекундным временем отклика в облученных тонких пленках Bi которые напылены при больщих углах к нормальному направлению подложки. При облучении с длиной волны 10 мкм зти детекторы обнаруживают отклик с обратным знаком по сравнению с откликом для видимого света, котрый генерируется за счет хорошо известного термозлектрического зффекта. Другие тонкопленочные металлические детекторы, например пленки Cr, работающие на том же зффекте, не обнаруживают явления обращения знака при длине волны 10 мкм. Мы приписываем явление обращения знака в висмуте зффекту сопротивления фотонов, связанному с внутризонным переходом, индуцированным излучением с длиной волиы 10 мкм.

     

Photoacoustic study of a two-layer system: Implanted silicon

Summary We have studied the behaviour of photoacoustic response of implanted silicon samples in order to measure the thermal conductivity of damaged layers; the results allow us to determine such a parameter simply by the phase difference measurement between implanted and unimplanted regions of the sample.

---

Riassunto è stata studiata la risposta fotoacustica di campioni di silicio impiantato allo scopo di misurare la conducibilità termica degli strati danneggiati; i risultati permettono di determinare questa grandezza misurando semplicemente la differenza di fase tra la zona impiantata e quella cristallina del campione.

---

Резюме Исследуется поведение фотоакустического отклика на образцах имплантированного кремиия, чтобы измерить теплопроводность поврежденных слоев. Полученные результаты позволяют получить величину теплопроводности с помощью измерения разности фаз между имплантированной и неимплантированной областлми образца.

     

Determination of optical properties of SnO2 films

Summary The optical properties of conductive transparent thin films of undoped SnO₂, prepared by using magnetron supttering, were studied by measuring the transmittance and the reflectance between λ=0.25 μm and λ=3μm. The extracted optical constants are interpreted to give values of a direct band gap of the order of 4 eV and of an indirect band gap of the order of 3 eV. Typical SnO₂ films transmit ≈85% of visible light, have sheet resistanceR _∂ (100÷800) Ω_∂ and resistivities of (2.4·10⁻³÷1.8·10⁻²) Ω cm.

---

Riassunto Mediante la misura dei valori di transmittanza e di riflettanza per lunghezze d'onda comprese fra 0.25 μm e 3 μm, sono state studiate le proprietà ottiche di film sottili (trasparenti e conduttivi) di SnO₂ non drogato, preparati mediante sputtering. Dai valori così ottenuti sono stati ricavati valori del gap diretto dell'ordine di 4 eV e di quello indiretto dell'ordine di 3 eV. Un film di SnO₂ presenta tipicamente valori della transmittanza intorno all'85%, per luce visibile,R _∂ intorno ai (100÷800) Ω_∂ e resistività fra 2.4·10⁻³ e 1.8·10⁻² Ω cm.

---

Резюме Пзмеряя величины пропускания и отражения в области длин волн между λ=0.25 мкм и λ=3 мкм, исследуются оптические свойства проводящих прозрачных тонких пленок нелегированного SnO₂, приготовленных с помощью напыления. Из полученных оптических постоянных извлекаются значения прямой щели, порядка 4 эВ, и непрямой щели, порядка 3 эВ. Типичные пленки SnO₂ пропускают ∼85% видимого света, имеют сопротивлениеR _∂ (100÷800) Ω_∂ и удельные сопротивления в области (2.4·10⁻³÷1.8·10⁻²) Ом·см.

     

Oxidation-induced changes in the electro-optical properties of thin copper films

Summary The room temperature oxidation of vapour deposited copper films has been investigated as a function of film thickness and time by the sheet resistance and optical transmittance measurements. An increase of both sheet resistance and transmittance with a tendency to saturation has been observed. Time variation of the sheet resistance shows that the kinetics of oxidation could be described by a model whereby an initial logarithmic oxide growth changes to an inverse logarithmic one as time progresses; the thicker the film, the longer the change-over time. Absorption coefficients of oxidized films show that the resulting oxide is most probably Cu₂O. Evaluation of the oxidized films for possible use as transparent electrode material shows the existence of an optimum thickness value.

---

Riassunto Si è studiata l’ossidazione a temperatura ambiente di pellicole di rame depositate per vaporizzazione in funzione dello spessore della pellicola e del tempo mediante la resistenza del foglio e misurazioni di trasmittenza ottica. Si è osservato un aumento sia della resistenza del foglio, sia della trasmittenza con una tendenza alla saturazione. La variazione temporale della resistenza del foglio mostra che la cinetica di ossidazione potrebbe essere descritta da un modello con cui un’iniziale crescita logaritmica dell’ossido cambia in una logaritmica inversa al crescere del tempo; più spessa è la pellicola più lungo è il tempo del cambiamento. I coefficienti di assorbimento delle pellicole ossidate mostrano che l’ossido risultante è molto probabilmente il Cu₂O. La valutazione delle pellicole ossidate per un possibile uso come materiale di elettrodo trasparente mostra l’esistenza di un valore ottimo dello spessore.

---

Резюме Исследуется окисление при комнатной температуре пленок меди в зависимости от толщины пленки и времени, используя измерения сопротивления слоя и оптической прозрачности. Наблюдается увеличение сопротивления слоя и прозрачности с тенденцией к насыщению. Временное изменение сопротивления слоя показывает, что кинетика окисления может быть описана с помощью модели, согласно которой начальный логарифмический рост окисла изменяется на обратно логарифмический, когда время увеличивается; для более толстой пленки изменение происходит при больщих временах. Коэффициенты поглощения окисленных пленок показывают, что результирующий окисел представляет Cu₂O. Оценка возможности использования окисленных пленок в качестве прозрачного материала электродов указывает на существование оптимальной толщины пленки.

     

Switching phenomena in CdIn2S4 thin films

Summary Two kinds of switching phenomena in CdIn₂S₄ polycrystalline and amorphous thin films which were prepared by the vacuum evaporation method and the d.c. sputtering method, respectively, were studied. One is the so-called memory switching phenomenon arising from the low resistive filament path. Another is a characteristic switching phenomenon in which the resistivity abruptly changes whenever the ambient temperature reaches a critical value. The switching time is fast and about 100 ns. This switching phenomenon is related to the native defects in the CdIn₂S₄ lattice, because they can be observed in the polycrystalline as well as in the amorphous thin films. Paper presented at the ?V International Conference on Ternary and Multinary Compounds?, held in Cagliari, September 14–16, 1982.