双离子束溅射法制备SiOxNy薄膜的结构与发光

本文采用双离子束溅射沉积法制备了SiOxNy复合薄膜,XRD、TEM测试表明薄膜呈非晶态,FTIR及XPS测试表明薄膜成分由Si、O、N组成,在室温下可观察到样品有400 nm（紫光）、470 nm（蓝光）的光致发光.根据测试分析研究了SiOxNy薄膜的可能的发光机理：470 nm处发光峰为来自于硅基薄膜中中性氧空位缺陷（O3≡Si-Si≡O3）,是由于氧原子配位的二价硅的单态-单态之间的跃迁所致,其发光强度随退火温度的升高而变化,800℃时最大,高于800℃时慢慢减弱;400 nm发光峰的发射与薄膜中的Si、O、N所形成的结构有关,它可能来自于Si、O、N结构所形成的发光中心,该峰位的强度随退火温度的升高而增强.     

退火对两种硅基薄膜的结构及发光影响

采用双离子束共溅射沉积方法制备了两种复合硅基薄膜SiOxCy和SiOxNy薄膜,对两种薄膜进行后退火处理,并分别对样品进行PL、FTIR、XPS谱测试分析,比较退火前后的发光及结构的变化。两种样品的光致发光测试谱(PL)表明:退火前后都有两个发光峰位-都存在470nm的发光峰位,它来自于硅基薄膜中中性氧空位缺陷(O3≡Si-Si≡O3),是由于氧原子配位的二价硅的单态-单态之间的跃迁所致,其发光强度随退火温度的升高而变化。进一步的FTIR和XPS的测试谱表明另外一个发光峰位420nm(SiOxCy薄膜)和400nm(SiOxNy薄膜)分别来自于掺杂杂质(C和N)与硅基薄膜中的Si、O组成的复合结构。而两种样品经过退火处理后掺杂所引起的发光峰位强度随退火温度的升高而增强,说明退火温度的升高有利于发光机制的形成。     

N含量对Ta-Si-N扩散阻挡层阻挡性能的影响

采用磁控反应溅射技术在p型Si(111)衬底上制备了Ta-Si-N薄膜与Cu/Ta-Si-N复合结构,并对样品进行了快速热处理.用四探针电阻测试仪、原子力显微镜、X射线衍射和扫描电镜等对样品的电阻、形貌、结构与特性进行了分析表征.实验结果表明,随着N含量的增加,Ta-Si-N薄膜的方块电阻单调增加,表面粗糙度则先减小后增大;Ta-Si-N阻挡层的阻挡性能随N含量的增加而有所增强,但当N含量过大时,阻挡性能的提升并不明显;沉积态的Ta-Si薄膜为纳米晶结构,掺入N后,薄膜成为非晶态,但在高温热处理后Ta-Si-N薄膜重新结晶,铜原子主要通过晶界扩散并与Si反应,导致阻挡层失效.     

N_2O等离子体处理对富硅氮化硅薄膜发光的影响

采用PECVD方法制备富硅氮化硅(SiNx)薄膜,并研究了N2O等离子体处理对SiNx薄膜光致发光(PL)及电致发光(EL)的影响。研究结果表明,N2O等离子体处理前后SiNx薄膜的PL发光峰均位于430nm处,且强度变化不大。而其EL发光峰位于600nm处,处理后强度有所提高。但经过高温热处理后,EL强度会大幅度降低。这主要是由于N2O等离子体处理在薄膜中引入N原子,这些N原子与Si原子结合,消除Si的悬挂键,降低了非辐射复合中心的浓度;而热处理后发生的原子重排,使得N原子与Si原子断开,进而与O原子结合,致使EL强度降低。     

射频磁控溅射制备硼碳氮薄膜

采用射频磁控溅射技术,用六角氮化硼和石墨为溅射靶,以氩气(Ar)和氮气(N2)为工作气体,在Si (100)衬底上制备出硼碳氮薄膜.通过X射线衍射(XRD)、傅里叶红外吸收光谱(FTIR)和X射线光电子能谱(XPS)等分析手段对样品结构、组分进行了分析.结果表明,样品的组成原子之间实现了原子级化合,且薄膜为乱层石墨结构.样品中B、C、N的原子比近似为1:1:1.     

Al/Al2O3多层膜的表面和界面的分析研究

用热蒸发沉积和自然氧化及加热法制备纳米量级的Al/Al2O3薄膜和多层膜.用X射线光电子谱仪(XPS)和透射电镜(TEM)对样品进行检测.XPS实验说明自然氧化的Al2O3膜层厚在2～5 nm.Al/Al2O3薄膜及多层膜的O与Al的原子浓度比为1.43～1.85.Ar离子刻蚀的XPS实验结果(刻蚀速率为0.09 nm/s)说明2个对层的Al/Al2O3多层膜截面样品具有周期性结构.TEM观察到了5个对层的Al/Al2O3多层膜的层状态结构,其周期为4 nm.由此说明,热蒸发及自然氧化法是制备纳米量级的Al/Al2O3多层膜的有效方法.     

Si基富Ge含量Si1-x-yGexCy异质结构的热退火行为研究

研究了Si基富Ge含量的Si1-x-yGexCy异质结构的热退火地为,采用等离子体增强化学气相淀积（PECVD）法在Si(100）衬底上淀积一层厚度为170nm的Si1-x-yGexCy薄膜（x-0.7,y-0.15),并在其上覆盖－Ge层,将样品分别在650度和800度下进行N2氛围下热退火20min。用拉曼谱（Raman),俄歇电子能谱（AES）以及X射线光电子能谱XPS等方法对样品进行研究。研究结果表明,低温PECVD法生长的Si1-x-yGexCy薄膜是一种亚稳结构,Ge/Si1-x-yGexCy/Si异质结构在650度下呈现不稳定性,薄膜中的Ge,C相对含量下降,且在界面处出现Ge,C原子的堆积,经过800度下退火20min的样品中C 含量基本为0,Ge相对含量下降至约20％左右,且薄膜的组分比较均匀。     

可钢化TiO2-Si3N4-CrNx-Ag-NiCrOx-ZnO-Si3N4玻璃涂层的制备和性能表征

采用磁控溅射法制备了可钢化TiO2-Si3 N4-CrNx-Ag-NiCrOx-ZnO-Si3 N4复合玻璃涂层(TSCANZSLow-E玻璃),并对其微观结构和物理性能进行了测试.AFM分析发现,薄膜表面光滑平整,粗糙度Ra为0.323nm;XPS探测到膜层表面存在TiO2和Si3N4;四探针面电阻测试仪测定薄膜方阻Rs为8.81Ω/□,比辐射率值为0.108;光学性能分析显示可见光透过率达81%,在2500nm处的中远红外区反射率达80%;剥落实验证明薄膜与玻璃基底之间具有良好的附着性;钢化测试结果符合国标要求.     

薄膜厚度对YBCO超导薄膜微结构及临界电流密度的影响

用MOD方法在LAO基片上沉积不同厚度的YBCO薄膜.用X射线衍射仪对这一系列样品进行表征分析,研究随着薄膜厚度的增加微结构的变化及临界电流密度的变化.X射线衍射分析发现YBCO薄膜取向度随薄膜厚度的增加,在800nm时取得最佳值之后又随厚度增加由强变弱.晶格常数c随着膜厚的增加而增大.本研究对这一系列样品进行了φ扫描分析和摇摆曲线半高宽的计算,并对800nm的YBCO薄膜做了倒易空间图谱分析,实验结果发现800nm的YBCO薄膜晶化比较好.本研究还分析了薄膜厚度对YBCO薄膜临界电流密度的影响.     

喷雾热解法制备SnO2:F+Sb薄膜的结构及性能研究

采用喷雾热解法在玻璃基板上制备了SnO2F+Sb薄膜,对薄膜的结构及性能进行了研究.用STM对薄膜表面进行表征,发现薄膜表面光滑平整,粗糙度Ra为16.283nm.四探针测试仪测定薄膜方阻为60Ω/□,电阻率为2.1×10-3Ω·Cm.用XRD表征薄膜结构,薄膜为四方相多晶SnO2结构,说明掺杂没有该变薄膜结构.对薄膜的光学性能进行了测试,可见光透过率达到80%,在2500nm处的中远红外区反射率由镀膜前的6%上升到36%.按国家标准测试了镀膜玻璃耐酸碱稳定性,实验前后薄膜的可见光透过率变化＜3%,符合国家标准.同时本研究还对镀膜玻璃的保温性能进行了测试,结果表明本实验制备的镀膜玻璃具有较好的保温性能.     

Ag-SiO2复合纳米颗粒薄膜的制备及其光学特性研究

利用溶胶一凝胶法在玻璃基底上成功制备了Ag—SiO2复合纳米颗粒薄膜,SEM、TEM和XRD的表征分析表明Ag是以单晶纳米颗粒的形态均匀分散在SiO2基质中,形成了多孔状Ag—SiO2复合纳米颗粒薄膜。从Ag—SiO2复合纳米颗粒薄膜的光吸收谱发现,该复合薄膜中鲰纳米颗粒具有较强的等离子共振吸收峰,峰位在430nm附近,随着复合薄膜中Ag、Si摩尔比的逐渐增大,等离子共振吸收峰不断增强且发生蓝移,蓝移量可达30nm;研究Ag—SiO2复合纳米颗粒薄膜的光敛发光特性发现,当激发波长为220nm时,复合薄膜分别在330nm和375nm处出现了两个发光带,随着复合薄膜中Ag、Si摩尔比增大到0．11,两发光带均逐渐增强,继续增加Ag、Si摩尔比,两发光带又逐渐减弱,且375nm处的发光带变化尤为显著。     

Optical properties of a strained GaAs/Si heterostructure after rapid thermal annealing

Photoluminescence (PL) and Raman spectroscopy measurements on GaAs/Si heterostructures grown by molecular beam epitaxy were performed in order to characterize the optical properties of the samples after thermal treatment. The crystalline quality of the annealed GaAs/Si was remarkably improved in comparison with that of the as-grown GaAs/Si. The results of PL spectra for rapidly thermally annealed GaAs/Si showed that the peaks at 1.501 and 1.485 eV, which are related to intrinsic bands, and the peak at 1.467 eV, which can be attributed to impurities, were well resolved. The magnitude of the deformation in the GaAs layer, as determined from the PL measurements, was approximately 2.1 × 10^7minus;3. The ratio of the peak intensity of the longitudinal optical phonon to that of the transverse optical phonon for rapidly thermally treated GaAs/Si increased dramatically in comparison with the corresponding rates for the as-grown GaAs/Si. These results indicate that the crystallinity of the GaAs epilayer is improved by thermal treatment.     

PZT薄膜反提拉生长的PbO挥发与退火条件研究

通过一新的溶胶-凝胶工艺:反提拉涂膜方法,在Si(100)和Pt(111)/Ti/SiO2/Si(100)基片上制备了PZT(Zr/Ti=52/48)铁电薄膜,并研究了退火工艺及其PbO的挥发对薄膜微结构、表面形貌、取向、及铁电性能的影响.本文首次提出并应用反提拉涂膜技术制备了PZT薄膜,此技术相对于传统的溶胶-凝胶工艺具有以下几方面的优点:操作控制简单方便、成本低、原料利用率高、无污染等.研究发现PZT薄膜通过增加PT晶种层后可以抑制PbO的挥发,同时薄膜呈现较强的(110)取向;在薄膜的退火处理过程中还发现氧气氛有助于降低PbO的挥发、促进晶粒的长大和降低钙钛矿的晶化温度,在氧气氛中退火的PZT薄膜显示了很好的铁电性能,其剩余极化强度明显增大而矫顽场只有极小的增加.     

氢化碳化硅(SixC1-x∶H)薄膜发光特性和纳米线发光增强研究

氢化碳化硅薄膜作为一种宽带隙的半导体材料,具有优越的物理特性,其在光电子器件上的潜在应用引起了人们的兴趣。利用等离子增强化学气相沉积(PECVD)系统制备了一系列氢化碳化硅薄膜,通过改变反应前驱物及流量比调节薄膜的室温光致发光性质。实验发现在一定范围内随着流量比R(CH_4/SiH_4)的提高,氢化碳化硅薄膜的光致发光峰位蓝移且发光强度增强;同时反应前驱物中的氢会极大影响氢化碳化硅薄膜的发光强度。通过椭偏仪(Ellipsometer)测量了薄膜的光学常数,发现薄膜沉积速率随着流量比R的增加而降低;傅里叶红外光谱仪(FTIR)测试表明Si-C有序度随着流量比的增加而增大。同时研究了三维纳米线结构对多态碳化硅薄膜发光性质的影响。光致发光测试结果表明三维纳米线结构可以有效提高薄膜的光致发光强度。     

Photoluminescence and optical limiting properties of silicon nanowires

Si nanowires (SiNWs) have been produced by thermal vaporization on Si(111) substrate without catalysts added. The grown SiNWs have been characterized by Raman scattering, SEM, XRD, and electron diffraction and shown to be highly crystalline with only little impurities such as amorphous Si and silicon oxides. Photoluminescence (PL) study has illustrated that the Si band-to-band gap increases from 1.1 eV for bulk Si to 1.56 eV for the as-grown SiNWs due to quantum confinement effect. A strong PL peak at 521 nm (2.37 eV) is attributed to the relaxation of the photon-induced self-trapped state in the form of surface Si-Si dimers, which may also play an important role in optical limiting of SiNWs with 532-nm nanosecond laser pulses. With the observation of optical limiting at 1064 nm, nonlinear scattering is believed to make a dominant contribution to the nonlinear response of SiNWs.     

用射频磁控溅射法制备的Zn1-xMgxO薄膜光致发光特性

用射频磁控溅射法在Si(100)衬底上生长了一组Zn1-xMgxO(x=0～0.16)薄膜.并在不同温度下退火.对薄膜的光致发光研究表明,在薄膜的发射谱的紫外区域有分别对应自由激子(以及相应的声子伴线)和电子-空穴等离子体的发光机制,其中后者有5倍超线性的受激发射,其受激发射阈值与薄膜的退火温度相关,样品中最低受激阈值为40kW/cm2.     

(In)GaSb/AlGaSb quantum wells grown on Si substrates

We have successfully grown GaSb and InGaSb quantum wells (QW) on a Si(001) substrate, and evaluated their optical properties using photoluminescence (PL). The PL emissions from the QWs at room temperature were observed at around 1.55 μm, which is suitable for fiber optic communications systems. The measured ground state energy of each QW matched well with the theoretical value calculated by solving the Schrödinger equation for a finite potential QW. The temperature dependence of the PL intensity showed large activation energy (∼ 77.6 meV) from QW. The results indicated that the fabricated QW structure had a high crystalline quality, and the GaSb QW on Si for optical devices operating at temperatures higher than room temperature will be expected.     

Effects of hydrogenation and aging on the optical properties in porous Si layers

The effects of hydrogenation and aging on the optical properties in porous Si (PS) layers were investigated by using photoluminescence (PL) measurements. When the hydrogenated PS layers were aged in air, the intensity of the PL spectrum increased. The emission peak for the hydrogenated PS layers shifted to higher energy with decreasing H₂/N₂ ratio. The relation of the dehydrogenized states in the as-formed PS surface to the quantum states of Si nanoparticles with relatively small sizes is discussed. These results indicate that the optical properties of PS layers are significantly affected by hydrogenation and aging.     

Optical emission from LiNbO3(:Fe)/porous Si structures

Using pulsed laser deposition, a layer of LiNbO₃(:Fe) film with a thickness of 180 nm was coated onto porous Si (PS) stored in air for 1 year. A photoluminescence (PL) band enhanced about three times was observed at ∼625 nm with a same peak position as that of the stored PS. It is revealed that a new PL excitation band occurs at ∼363 nm, which is nearly equal to the fundamental optical absorption edge position of LiNbO₃. The X-ray diffraction results disclose that the enhancement of the PL intensity is closely related to formation of a textured LiNbO₃ film. Based on spectral analysis, we attribute the enhanced PL to optical transition in the E′ defect centers localized at the surfaces of PS nanocrystals, whereas the photoexcited carriers mainly come from the coated LiNbO₃ film. This kind of LiNbO₃(:Fe)/PS structures is expected to have important applications in modern ferroelectric optoelectronics.     

电沉析条件对钛合金表面液相沉积类金刚石薄膜的影响

在钛合金表面沉积类金刚石膜能改进钛合金的生物相容性，拓展其在人体植入材料中的应用。探讨了用液相电解沉积法在钛合金表面制备类金刚石薄膜的新方法。讨论了不同沉积条件对膜的影响。在1650和1850V时可以得到坚固的棕色膜。沉积36h后，膜厚基本不变。沉积膜的Raman谱图表明，在1650和1850V沉积得到的是类金刚石薄膜，而在2000V时无法得到类金刚石薄膜。对膜的XPS分析表明，其主要成份是碳。XPS谱还表明在1650V时得到的膜可以将钛合金表面完全覆盖，而在1850V时则不能。以SEM分析表明在1650和1850V时得到的膜是由粒径约为400nm的小颗粒组成，而在2000V时得到只是疏松结构。并对类金刚石膜及钛合金的血液相容性进行了比较。