SiGe上NbAlO栅介质薄膜微结构和电学性能分析

本文针对SiGe上Al2O3/NbAlO/Al2O3三明治结构介质栈的热稳定性和电学性能进行了研究.高分辨透射电镜(HRTEM)测试表明退火后薄膜是结晶的,同步辐射X射线反射率(XRR)和X射线衍射(XRD)分析表明在薄膜中存在超晶格结构,有0.5nm的界面层存在,X射线光电子谱(XPS)表明界面层主要成分是SiOx,...     

Mn、Co掺杂SiC薄膜结构与光致发光性能研究

采用射频磁控溅射技术和复合靶材方法制备了掺Mn,掺Co和Co、Mn共掺的SiC薄膜,经高温退火后进行了光致发光(PL)谱的测量,还用X射线衍射(XRD),傅立叶变换红外光谱(FTIR),扫描电镜(SEM)等表征手段分析了薄膜的相结构和表面形貌,并与光致发光的结果进行了对比研究.结果表明,掺Mn、Co使SiC晶格发生畸变,X射线衍射峰强度下降,Si-C吸收谱变宽,Si-C键振动减弱,Si-O基团的振动增强.样品在室温条件下均呈现出强的紫光发射特性,发光峰均位于414nm(3.0eV),认为414nm处的光致发光峰对应于光激发产生的电子从导带底到Si空位浅受主能级之间的辐射跃迁,其强度取决于Si空位的浓度.     

等离子体辅助MOCVD生长的ZnO薄膜退火改性研究

用等离子体辅助MOCVD法在蓝宝石 (α Al2 O3)上生长了ZnO薄膜 ,测试了其退火和未退火薄膜的电阻率、电子浓度、迁移率、激光阈值 ,并通过X光衍射、光致发光方法表征了ZnO薄膜的质量 ,其结果是 :退火薄膜的电子浓度低达 10 15/cm3 量级、激光阈值降低近 30倍、X光衍射峰半高宽是 0 .2 9°、在 388nm附近的光致发光谱峰半高宽为 0 .32nm。这表明退火使ZnO薄膜的质量得到大幅度提高     

Mg2Si半导体薄膜的磁控溅射制备

采用磁控溅射技术和退火工艺制备出Mg2Si半导体薄膜,研究了退火时间对Mg2Si薄膜的形成和结构的影响.首先在Si(111)衬底上溅射沉积380nm Mg膜,然后在退火炉内氩气氛围500℃退火,退火时间分别为3.5h、4.5h、5.0h、5.5h、6.0h.采用X射线衍射和扫描电镜对薄膜的结构和形貌进行了表征.结果表明,采用磁控溅射方法成功地制备了环境友好的半导体Mg2Si薄膜.Mg2Si薄膜具有Mg2Si(220)的择优生长特性,最强衍射峰出现在40.12°位置;随着退火时间的延长,Mg2Si外延薄膜的衍射峰强度先逐渐增强后逐渐减弱,退火5h后,样品的衍射峰最强.Mg2Si晶粒随着退火时间的延长,先逐渐增大,退火5h后逐渐减小.     

先驱硼薄膜的质量对MgB2超导薄膜的影响

以高纯乙硼烷(B2H6)为B源,采用化学气相沉积(CVD)方法在多晶Al2O3衬底上沉积B薄膜,然后在Mg蒸气中异位退火来制备MgB2超导薄膜.通过X射线衍射和MgB2超导薄膜的电阻-温度曲线,研究了先驱硼薄膜的质量对MgB2超导薄膜的影响.     

CdZnTe薄膜的CdCl2退火及性能表征

采用近空间升华法制备了CdZnTe薄膜,并对其进行CdCl2退火,采用扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)、紫外光谱仪、I-V测试仪等研究了退火对薄膜表面形貌、成分、结构以及光电性能的影响。结果表明,经过CdCl2退火后薄膜的晶粒尺寸明显增大,晶粒分布更加均匀;XRD分析结果显示,退火后薄膜的最强峰(111)峰的半峰宽变窄,薄膜沿(111)方向的择优取向明显增强;退火后薄膜的光学透过率降低,截止边红移,光学禁带宽度减小;薄膜的电阻率在退火后下降了两个数量级。     

铜铟铝硒薄膜离子束溅射制备与表征

采用离子束溅射方法,在玻璃衬底上沉积Cu,In,Al和Se,在同一真空环境下进行退火处理,制备得到铜铟铝硒(CIAS)太阳电池吸收层薄膜。利用扫描电镜、X射线衍射仪、能谱仪、四探针系统、分光光度计分别对薄膜的表面形貌、物相结构、晶粒尺寸、元素含量、电阻率和禁带宽度等特性进行分析。结果表明:通过控制铜铟、Cu、Al、Se各靶材的镀膜时间,实现在Cu In Se2薄膜上掺杂Al元素,制备的CIAS薄膜呈现黄铜矿结构。薄膜(112)衍射峰峰位,表面电阻率和禁带宽度随着铝含量的增加而增加,调节Al元素的含量可以使薄膜表面均匀。当Al的原子分数比X(Al)=14.47%时,(112)衍射峰最强,半高宽最小,结晶最好。当X(Al)=11.8%,N(Al)/(N(In)+N(Al))=0.37,禁带宽度为2.12 e V,薄膜表面形貌最均匀。     

溶胶-凝胶法生长(002)高度择优取向的ZnO:Al薄膜

采用溶胶-凝胶法在石英衬底上制备了高度择优取向的ZnO:Al薄膜.用X射线衍射(XRD)、扫描电子显微镜(SEM)分别对薄膜结构和形貌进行了表征,用紫外-可见透射光谱和四探针研究了薄膜的光电性能.结果表明:制备的ZnO:Al薄膜为六角纤锌矿结构,且具有明显的c轴择优取向;Al离子的掺杂浓度和退火温度对薄膜的结构、光电性能有一定的影响,薄膜在可见光区的光透过率为80%～95%;Al的掺杂浓度为1%样品在600℃下空气中退火1h后,薄膜最低的电阻率为7.5×10-2Ω·cm.     

Al/MoO3和Al/Fe2O3纳米含能薄膜制备与性能表征

使用自动控制磁控溅射仪制备纳米级Al/MoO3和Al/Fe2O3含能薄膜,使用扫描电镜(SEM)、原子力显微镜(AFM)对其形貌进行分析,使用X射线衍射(XRD)、X射线光电子能谱(XPS)分析薄膜组分,利用差示扫描量热(DSC)进行热力学分析。分析显示,含能薄膜结构完整,层状结构清晰;Al/MoO3纳米薄膜中MoO3有较大部分被还原为Mo2O5和MoO2,Al/Fe2O3纳米薄膜中Fe2O3有部分被还原为FeO,含能薄膜中Al有少部分被氧化为非晶结构的Al2O3。含能薄膜放热峰起始温度较低,活化能较小,反应活性较高,放热量较大,分别为3198和1680J/g。     

高介电栅介质材料HfO_2掺杂后的物理电学特性(英文)

采用激光分子束外延法(LMBE)在P型Si(100)衬底上沉积了(HfO2)x(Al2O3)Y(NiO)1-x-y,栅介质薄膜,研究了其热稳定性以及阻挡氧扩散的能力.X射线衍射表明在HfO2中掺入Ni和Al元素明显提高了其结晶温度.原子力显微镜测试显示:在N2中退火后薄膜表面是原子级平滑连续的,没有发现针孔.900℃N2中退火后的薄膜在高分辨透射电镜下没有发现硅酸盐界面层.实验结果表明在氧化物薄膜与硅衬底之间引入Ni-Al-O置入层能够防止硅酸盐低介电界面层的生成,这有利于MOS晶体管的进一步尺度缩小.     

Preparation and characterization of MgO nanorods coated with SnO2

MgO nanorods have been grown by thermal evaporation of Mg3N2 powders on Si (100) substrates coated with gold (Au) thin films. The MgO nanorods grown on Al2O3 (0001) were 0.1-0.2 microm in diameter and up to a few tens of micrometers in length. MgO/SnO2 coaxial nanorods have also been prepared by atomic layer deposition (ALD) of SnO2 onto the nanorods. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis results indicate that the MgO-cores and the SnO2 shells of the annealed coaxial nanorods are of a single crystalline nature with cubic and orthorhombic structures, respectively. The photoluminescence (PL) spectroscopy analysis results show that SnO2 coating slightly increases the PL emission intensity of MgO nanorods. The PL emission of the SnO2-coated MgO nanorods is found to be considerably enhanced by thermal annealing and to strongly depend on the annealing atmosphere. The PL emission intensity of the MgO/SnO2 coaxial nanorods has been significantly increased by annealing in a reducing atmosphere. The origin of the PL enhancement by annealing in a reducing atmosphere is discussed on the basis of energy-dispersive X-ray spectroscopy analyses.     

Effect of annealing temperature and composition on photoluminescence properties of magnetron sputtered SiCN films

Silicon carbonitride (SiCN) films were prepared by means of reactive magnetron sputtering of a sintered SiC target on n-type Si (1 0 0) substrates in the reactant gas of nitrogen, and then the films were respectively annealed at 600, 800 and 1100 °C for 5 min in nitrogen ambient. The films were characterized by energy dispersive spectrometer, X-ray diffraction, Fourier transform infrared spectroscopy and photoluminescence (PL) spectrophotometry. Intense PL peaks at 370, 400 and 440 nm were observed at room temperature. The results show that annealing temperature and composition play an important role in the structures and PL properties of the films. The annealing temperature of 600 °C favors the formation of the SiC (1 0 9) crystal in the SiCN films, and results in a maximal PL peak. The intensity of the 440 nm PL peak can be improved by increasing the abundance of the Si-C bond.     

RF溅射稀土掺杂ZnO薄膜的结构与发光特性

通过射频磁控溅射技术在Si(111)衬底上制备了未掺杂和La、Nd掺杂ZnO薄膜.XRD分析表明,ZnO薄膜具有c轴择优生长,La、Nd掺杂ZnO薄膜为纳米多晶薄膜.AFM观测,La、Nd掺杂ZnO薄膜表面形貌较为粗糙.从薄膜的室温光致光谱中看到,所有薄膜都出现了395 nm的强紫光峰和495 nm的弱绿光峰,La掺杂ZnO薄膜的峰强度增大,Nd掺杂ZnO薄膜的峰强度减弱,分析了掺杂引起PL峰强度变化的原因.     

Origin of photoluminescence peaks in Ge–SiO2 thin films

Ge–SiO₂ thin films were prepared by the RF magnetron sputtering technique on p-Si substrates from a Ge–SiO₂ composite target. The as-deposited films were annealed in the temperature range of 300–1000 °C under nitrogen ambience. The structure of films was evaluated by X-ray diffraction, X-ray photoemission spectroscopy and Fourier transform infrared absorption spectroscopy. Results show that the content of Ge and its oxides in the films change with increasing annealing temperature (T_a), the photoluminescence (PL) characteristics are closely dependent on the contents of Ge and its oxides in SiO₂ matrix. The dependence observed strongly suggests that the PL peak at 394 nm is related to the existence of GeO and 580 nm to that of Ge nanocrystal (nc-Ge) in the films.     

Growth of MgO thin films with subsequent fabrication of ZnO rods: Structural and photoluminescence properties

We have grown magnesium oxide (MgO) films by the simple evaporation of MgB₂ powders. The subsequent deposition of ZnO by using an atomic layer deposition (ALD) technique generated the ZnO rods on MgO films, realizing the first production of rod-like structures using ALD. We have employed X-ray diffraction, scanning electron microscopy, transmission electron microscopy and photoluminescence (PL) spectroscopy to characterize the samples. PL of MgO films exhibited two emission bands peaked in the blue and blue-green region, respectively. The deposition of ZnO rods changed the shape of the PL spectrum.     

Photoluminescence of TiO2 films co-doped with Tb/ Gdand energy transfer from TiO2/Gd to Tb ions

Nanometer TiO₂ thin films doped with different concentration of Tb were prepared by sol-gel method and characterized by X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (TG-DTA), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. XRD results show preferentially oriented (101) anatase films. TEM image indicates that the TiO₂ films consist of TiO₂ grains with diameter about 15 nm. Under room temperature, strong visible luminescence of Tb³⁺ ions due to intra-4f shell transitions are obtained and the PL intensity is found to have a well matching relation with the doping concentration of Tb³⁺ ions. Concentration quenching of PL occurs when Tb³⁺ concentration exceeds a certain value (9.2 mol%). Furthermore, the luminescence intensity is improved obviously after co-doping with Gd³⁺ ions because of the sensitization effects of Gd³⁺ ions to Tb³⁺ ions in TiO₂ system. The energy transfer mechanism from TiO₂ and Gd³⁺ ions to Tb³⁺ ions was proposed.     

Fabrication of room temperature H2 gas sensor using pure and La: ZnO with novel nanocorn morphology prepared by sol–gel dip coating method

Nanostructured ZnO thin films with different lanthanum concentration (0, 1, 3, 5 and 10 wt%) were fabricated by sol–gel dip coating method on glass substrates. The effect of La incorporation on structural, morphological and H₂ gas sensing (room temperature) properties of the ZnO thin films was studied. Thermal behaviour of the xerogel of pure ZnO was studied by thermo gravimetric analysis/differential thermal analysis. The structural property of the films was analyzed by powder X-ray diffraction method and which revealed the presence of hexagonal structure. It emphasized that the film became (002) textured upon the 3 wt% of La incorporation onwards. The surface morphology was examined by field emission scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (EDX) and it substantiated that all the films have uniform distribution of particles with novel corn like morphology. Obviously, the length of nanocorn increases with the increase of La. The elemental composition was studied by EDX spectroscopy. Photoluminescence (PL) spectra revealed that La: ZnO thin films showed a blue shift and an enhanced PL intensity over that of the pure ZnO. The H₂ gas sensitivity of the pure and La: ZnO thin films were studied towards the concentration of 1,000 ppm. 1 wt% of La incorporated ZnO thin film showed a high sensitivity (51 %) than the pure and the higher La concentration. The increase and decrease of H₂ gas sensitivity of pure ZnO upon La incorporation is also discussed in this paper.     

Effects of sapphire substrates surface treatment on epitaxial ZnO thin films grown by MOCVD

The surface treatment effects of sapphire substrate on the quality of epitaxial ZnO thin films grown by metal-organic chemical vapor deposition (MOCVD) were studied. The sapphire substrates have been investigated by means of atomic force microscopy (AFM) and X-ray diffraction rocking curves (XRCs). The results show that sapphire substrate surfaces have the best-quality by CMP with subsequent chemical etching. The surface treatment effects of sapphire substrate on the ZnO thin films were examined by X-ray diffraction (XRD), atomic force microscopy (AFM) and photoluminescence (PL) measurements. Results show that the intensity of (002) diffraction peak of ZnO thin films on sapphire substrates treated by CMP with subsequent chemical etching is strongest. FWHM of (002) diffraction peak is narrowest and the intensity of UV peak of PL spectrum is strongest, indicating surface treatment on sapphire substrate preparation may improve ZnO thin films crystal quality and photoluminescent property.     

Photoluminescence from RF sputtered SiCBN thin films

Silicon carbon boron nitride (SiCBN) thin films were synthesized by reactive co-sputtering of silicon carbide (SiC) and boron nitride (BN) targets. As-deposited samples show distinct photoluminescence (PL) peaks at 465, 483 and 497 nm. The films were annealed in dry oxygen ambient at different temperatures to investigate the effect of annealing on film properties. Subsequent measurements on the annealed samples show diminished PL peak intensities. X-ray diffraction analysis shows that the as-deposited films are amorphous in nature and there is no change in the microstructure even after high temperature annealing. Surface characterization of the films by X-ray photoelectron spectroscopy reveals change in chemical composition at different annealing temperatures. Carbon concentrations in the films are sensitive to annealing temperatures and could cause the change in photoluminescence properties.     

Origin of photoluminescence peaks in Ge–SiO2 thin films

Ge–SiO₂ thin films were prepared by the RF magnetron sputtering technique on p–Si substrates from a Ge–SiO₂ composite target. The asdeposited films were annealed in the temperature range of 300–10000C under nitrogen ambience. The structure of films was evaluated by X–ray diffraction, X-ray photoemission spectroscopy and Fourier transform infrared absorption spectroscopy. Results show that the content of Ge and its oxides in thefilms change with increasing annealing temperature (Ta), the photoluminescence (PL) characteristics are closely dependent on the contents of Ge and its oxides in SiO₂ matrix. The dependence observed strongly suggests that the PL peak at 394 nm is related to the existenceof GeO and 580 nm to that of Ge nanocrystal (nc-Ge) in the films. © 2002 Elsevier Science Ltd. All rights reserved.