镓掺杂氧化锌透明导电薄膜的制备及其性能研究

采用射频磁控溅射方法在玻璃基片上制备了镓掺杂氧化锌(Ga∶ ZnO)透明导电薄膜,通过XRD、XPS、四探针仪和分光光度计等表征技术,研究了衬底温度对Ga∶ ZnO薄膜结构、组分、光学和电学性质的影响.结果表明:所有样品均为具有(002)择优取向的高质量透明导电薄膜,其晶体结构和光电性能与衬底温度密切相关.当衬底温度为673 K时,所制备的Ga∶ ZnO薄膜具有最大的晶粒尺寸(72.6 nm)、最低的电阻率(1.3×10-3Ω·cm)、较高的可见∶ZnO薄膜的光学能隙,结果显示随着衬底温度的升高,薄膜的光学能隙单调增加.     

CdS多晶薄膜的制备与光学性质研究

采用电子束蒸发法制备CdS多晶薄膜,研究了衬底温度和退火方式对薄膜光学性质的影响。XRD测试显示,制备样品为六方相多晶结构,沿(002)晶向择优取向生长,在200℃衬底温度时具有最大的择优取向度。对样品的紫外-可见透过谱测试表明,随着衬底温度的升高,薄膜的光吸收边逐渐变陡,光学带隙逐渐增大。退火后,CdS薄膜光吸收边变的更加陡直,光谱透过性能进一步提升,但光学带隙变化很小。此外,制备样品的XRD谱、光吸收边和光学带隙在250℃衬底温度下出现反常变化。同时对上述变化产生的根源进行了分析和讨论。     

溅射功率对脉冲磁控溅射沉积Cu2O薄膜结构和光学性能的影响

利用脉冲磁控溅射制备技术,采用单质金属铜靶作为溅射靶,在氧气(O2)和氩气(Ar)的混合气氛下,在石英玻璃衬底上制备了Cu2O薄膜.研究了溅射功率对脉冲反应磁控溅射沉积法在室温下对生长Cu2O薄膜结构、表面形貌及光学性能的影响.结果表明,在O2、Ar流量比(O2/Ar)为30∶80的气氛条件下,在60～90 W的溅射功率范围内可获得＜ 111＞取向的Cu2O薄膜;薄膜的表面粗糙度的均方根值随溅射功率的增加而增大;薄膜的光谱吸收范围为300 ～670 nm,不同溅射功率下制备的薄膜均在430 nm附近出现明显的带边吸收,其光学带隙(Eg)在2.15～2.53 eV之间变化.     

衬底温度对氢化非晶硅薄膜特性的影响

采用等离子增强化学气相沉积(PECVD)系统,以乙硅烷和氢气为气源,石英玻璃和单晶硅片为衬底制备了氢化非晶硅(a-Si∶ H)薄膜.采用扫描电子显微镜、X-射线衍射仪、台阶仪、紫外可见分光光度计、傅里叶变换红外光谱仪和电子能谱仪等分别表征了a-Si∶H薄膜的表面形貌、结晶特性、沉积速率,光学带隙,键合结构和Si化合态等特性.结果表明:随着衬底温度的增加,a-Si∶H薄膜表面的颗粒尺寸减小,均匀性增加,沉积速率则逐渐降低;衬底温度从80℃增加到130℃时,光学带隙显著增加,而在130℃至230℃范围内,光学带隙基本不随衬底温度变化;以SiH键对应的伸缩振动的相对峰强度逐渐增加,而以SiH2或(SiH2)n键对应的伸缩振动的相对强度逐渐减小;a-Si∶H薄膜中Si0+态的相对含量增加.因此,衬底温度大于130℃有利于制备优质a-Si∶H薄膜,230℃是沉积a-Si∶H薄膜的最佳衬底温度.     

氧氩比及基底温度对脉冲磁控溅射Cu2O薄膜结构和光学性能的影响

利用脉冲磁控溅射制备技术,采用单质金属铜靶作为溅射靶,在氧气(O2)和氩气(Ar)的混合气氛下在石英玻璃基底上制备Cu2O薄膜,研究了O2和Ar流量比(O2/Ar)及基底湿度对沉积的Cu2O薄膜结构、表面形貌及光学性能的影响.结果表明:在O2/Ar为30∶80的气氛条件下,基底温度在室温(RT)和100℃时均可获得单相的Cu2O＜ 111＞薄膜;薄膜表面致密、颗粒呈球状,粗糙度的均方根(RMS)值随基底温度增加而增大;薄膜的光谱吸收范围为300～ 650 nm,紫外区吸收较强,可见光区吸收强度较弱,吸收强度随基底温度的增加而增强,光学带隙(Eg)随基底温度的增加而减小.     

氧气流量对射频磁控溅射制备Cu2O薄膜性能的影响

通过磁控溅射方法在玻璃衬底上制备Cu2O薄膜,采用X射线衍射(XRD)、分光光度计、原子力显微镜(AFM)和X射线光电子能谱(XPS)等研究了氧气流量对Cu2O薄膜性能的影响.结果表明:氧气流量为4.2 sccm时,薄膜为单相的Cu2O,具有较高的结晶质量和可见光透过率,光学带隙为2.29 eV,薄膜的导电类型是p型且空穴浓度为2×1016 cm-3.通过XPS能谱分析Cu 2p3/2和O 1s结合能,确定了薄膜中Cu以+1价存在.     

Ag掺杂ZnO薄膜结构和光学特性研究

采用脉冲激光沉积技术制备出了Ag掺杂的ZnO薄膜.研究了Ag含量、衬底温度及氧压对ZnO结构和光学性能的影响.结果表明:Ag以替位形式存在于ZnO晶格中,Ag掺杂浓度较低时,样品具有高度c轴择优取向.衬底温度越高,薄膜的结晶质量越好,光学带隙越接近纯ZnO的带隙,而其紫外荧光峰在衬底温度为300 ℃时最强.氧压为10 Pa时,薄膜的结晶质量最好,紫外峰最强,其带隙则随氧压的增大呈先变窄后加宽的趋势.     

预制层衬底加热对Cu2ZnSnS4薄膜性能的影响

本文采用二步法制备Cu2ZnSnS4(CZTS)薄膜,首先通过真空热蒸发制备CuZnSn (CZT)预制层,其衬底加热温度分别为20℃、50℃、75℃和100℃,然后对所制备的CZT预制层在400℃下硫化60 min,从而制备出CZTS薄膜.利用XRD、Raman、SEM、反射谱和透射谱对所制备的CZTS薄膜进行了表征,实验结果表明,预制层衬底加热温度对CZTS薄膜结构与光学特性有很大影响,在衬底加热50℃时制备预制层硫化后所得CZTS薄膜具有高的结晶度、致密均匀的薄膜表面和最佳1.5 eV光学带隙.此外,与衬底未加热制备预制层在500℃和90 min最佳硫化条件下所制备的高纯CZTS薄膜相比,在50℃预制层衬底加热条件下所制备CZTS薄膜具有更好地结晶质量、更低的硫化温度和更短的硫化时间,这种现象表明衬底加热制备金属预制层利于更高品质CZTS薄膜的制备,可有效的降低硫化温度和缩短硫化时间,当前的研究结果为在低温下实现高质量CZTS薄膜的制备提供了一种有效的途径.     

衬底温度对In2S3薄膜结构及其性能的影响

采用超声喷雾热解法,在玻璃基底上一步合成了In2S3薄膜.研究了衬底温度对In2S3薄膜的结构、表面形貌、电学和光学性能影响.结果表明:所制备的In2S3薄膜均具有沿(220)面择优取向生长特性且无其他杂相,衬底温度对薄膜的均匀性、致密度、结晶程度均有明显影响,并因此影响薄膜的光电性能.薄膜的导电件随着衬底温度的升高迅速增强,但足在衬底温度为350℃时有所降低.衬底温度为300℃所制备的薄膜在可见光区透光率最高达到90;以上,禁带宽度达到2.43 eV.     

射频功率对ITZO薄膜结构、形貌及光电特性的影响

在室温下采用射频磁控溅射方法在玻璃衬底上制备了200 nm厚的铟锡锌氧化物(ITZO)薄膜,研究了不同功率下薄膜结构、形貌、光学和电学性能的变化规律.结果表明,ITZO薄膜为非晶薄膜并且有着良好的光电特性,其平均光学透过率超过了84;,载流子霍尔迁移率高达24 em2·V-1·s-1.随着射频功率从50 W上升到100 W,薄膜的光学带隙从3.68 eV逐渐增加到3.76 eV.研究发现,薄膜的电学性能强烈依赖于射频功率.随着功率的增加,薄膜的电学性能呈现出先变好后变差的变化规律.当射频功率为80 W时,ITZO薄膜拥有最佳的电学性能,其电阻率为3.80×10-4Ω·cm,载流子浓度为6.45×1020 cm-3,霍尔迁移率为24.14 cm2·V-1· s-1.     

Growth of BiSrCaCuO thin films by MOCVD

Thermodynamic analysis of the system Bi–Sr–Ca–Cu–O–C–H–Ar using the Gibbs energy minimization method was performed to propose feasible deposition conditions for the growth of superconducting Bi-2212 films. The results show that the films containing Bi-2212 can be prepared at temperatures above 1000 K under reduced pressure with the input ratio Bi : Sr : C a : Cu close to 2 : 2 : 1 : 2. The growth experiments were carried out in a cold-wall RF-heated quartz reactor at temperatures of 800 and 850°C and a total pressure of 1 kPa. 2,2,6,6-tetramethyl-3,5-heptanedionates of Cu, Ca and Sr and triphenylbismuth were used as metal precursors. The films were characterized by X-ray diffraction, electron microprobe analysis and scanning electron microscopy. The highest critical temperature determined by measuring the AC magnetic response was 71 K.     

氧氩混合气氛下脉冲激光沉积法制备YBa2Cu3O7-δ薄膜的研究

利用脉冲激光沉积法(PLD),在质量流量比为1∶3的氧气和氩气的混合气氛下,在STO(001) 基片上制备了外延的YBa2Cu3O7-δ(YBCO)超导薄膜.尽管薄膜表面分布有亚微米到微米量级颗粒,但与传统PLD制备YBCO的方法相比,大颗粒的密度要小得多.直流电阻和磁化率测量法同时证明了YBCO薄膜的超导转变温度(Tc)大于90 K. 在40 K时,零场临界电流密度(Jc)为63.8 MA/cm2,在5.2 T时达到最大钉扎力密度(Fpmax)387.9 GN/m3;在65 K时,零场Jc为28.3 MA/cm2,在2.6 T时Fpmax达到71.3 GN/m3;在77 K时,零场Jc为8.7 MA/cm2,在0.91 T时Fpmax达到12.1 GN/m3.研究结果为氧气和氩气混合气氛下PLD方法制备YBCO薄膜提供了重要实验数据.     

N-(4-吡啶甲基)-L-丝氨酸铜配合物的合成、晶体结构和磁性

氨基酸还原希夫碱HL (N-(4-吡啶甲基)-L-丝氨酸)与CuCl2·2H2O在室温条件通过扩散法合成了配位聚合物{[Cu2(L)2(Cl)2]·H2O}n(I).采用元素分析、红外光谱、X-射线单晶衍射、粉末衍射和热重分析进行了表征.两个结晶学独立Cu(II) 包含于其晶体结构中,Cu1为变形八面体CuO2N2Cl2几何构型;Cu2则呈现略有变形的四方锥结构.Cu1和Cu2通过配体L-的吡啶氮原子以及氯离子的桥连作用连接为2D网状结构.变温磁化率实验表明在温度为2~300 K,配合物I表现为铁磁性耦合.     

The influence of substrate temperature on the growth of sexiphenyl on mica(001)

Sexiphenyl thin films were grown by Hot Wall Epitaxy on air‐cleaved mica (001) surfaces at substrate temperatures between 293 K and 440 K. For the entire temperature range, organic thin films show nano‐needle like morphology. The nano‐needles grown at low substrate temperature (293 K) are shortest, and their growth is accompanied by a simultaneous formation of flat islands which disturbs the growth of nano‐needles. On the contrary, unusually long nano‐needles with typical lengths up to the mm range evolve during the growth at a substrate temperature close to the material's thermal desorption temperature at about 440 K. X‐ray diffraction reveals two different crystalline orientations for nano‐needles in the entire temperature range. At low substrate temperatures dominantly the (11 ) plane of the β‐phase is formed parallel to the mica (001) surface. At elevated temperatures another strong texture becomes dominant which is close to the (11 ) crystal orientation. In contrast to this, crystallites with the preferred orientation (001) parallel to the surface of the substrate are formed at low substrate temperature (293 K). This crystal orientation can be associated with flat islands observed in the early growth stage. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Influence of substrate temperature on microcrystalline structure and optical properties of ZnTe thin films

ZnTe thin films were deposited onto well‐cleaned glass substrates kept at different temperatures (Ts = 303, 373 and 423 K), by vacuum evaporation method under the pressure of 10^–5 Torr. The thickness of the film was measured by quartz crystal monitor and verified by the multiple beam interferometer method. The structural characterization was made using X‐ray diffractometer with filtered CuKα radiation. The grain sizes of the microcrystallines in films increases with increase in substrate temperature. The strain (ε), grain size (D) and dislocation density (δ) was calculated and results are discussed based on substrate temperature. Optical behaviour of the film was analyzed from transmittance spectra in the visible region (400–800 nm). The optical transition in ZnTe films is direct and allowed type. The optical band gap energy shows an inverse dependence on substrate temperature and thickness. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

MgO(100)衬底上生长BaTi2O5薄膜及其性能研究

利用脉冲激光沉积技术,在MgO(100)衬底上生长了BaTi2O5薄膜,探讨了沉积条件(衬底温度和氧分压)对薄膜结构的影响,并对其介电和光学性能进行了研究.结果表明:随衬底温度和氧分压的改变,BaTi2O5薄膜的物相和结晶取向逐渐变化;适宜的脉冲激光沉积工艺为衬底温度950~1000 K、氧分压12.5 Pa,在该条件下获得了b轴方向择优生长的BaTi2O5薄膜;该薄膜具有较高的居里温度(750 K),介电常数达2000,而且在可见光和红外波长范围内具有较高的透过率.     

Growth and electrical properties of epitaxial CuInS2 thin films on GaAs substrates

CuInS₂ thin films with thicknesses in the range of 500 Å were deposited onto semi-insulating (111) A-oriented GaAs substrates by flash evaporation in the substrate temperature range T_sub = 570 … 870 K. Epitaxial growth begins at T_sub = 645 K. The films had always the chalcopyrite structure. Indications to a transition from the chalcopyrite phase to the sphalerite phase were observed at T_sub = 870 K. Films grown at T_sub ≦ 800 K showed n-type conductivity whereas at growth temperatures T_sub ≧ 850 K the films were always p-type conducting. A donor level and an acceptor level with ionization energies of 0.24 eV and 0.22 eV, respectively, were found from an analysis of the electrical measurements.     

Analysis of current ‐ voltage ‐ temperature characteristics of In and Cu contacts on n‐type MoSe2 single crystals

The current voltage characteristics of In / Cu with n‐type MoSe₂ Schottky diodes were measured over a wide temperature range 50 < T < 300 K. The interface formed by In and MoSe₂ shows ohmic behavior after annealing the contact at 100 °C for 12 h. The ohmic nature was retained at all the measured temperatures. The Cu ‐ nMoSe2 interface formed a Schottky junction diode with a good rectification ratio. The Schottky barrier height and the ideality factor thereby obtained were 0.72 eV and 1.45, respectively, at room temperature. Below room temperature, the barrier height and the ideality factor vary with decreasing temperature. The changes are significant at low temperatures. Barrier height inhomogeneities at the interface cause deviation in the zero‐bias barrier height and the ideality factor at low temperatures, and produce extra current such that I‐V characteristics remain consistent with the thermionic emission mechanism. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

射频磁控溅射生长ZnO薄膜及性能研究

采用射频磁控溅射技术在玻璃衬底生长ZnO及ZnO∶ Al薄膜,通过改变氩氧比、衬底温度和溅射功率获得样品.用X射线衍射仪、紫外-可见分光光度计、扫描电子显微镜进行表征.结果发现:室温下40W的溅射功率1h的溅射时间,改变氩氧比获得样品.XRD图谱中无明显衍射峰出现;紫外可见光分光光度计测试结果显示400nm波长以下,透光率在90;以上.说明薄膜生长呈无定形.衬底温度高于200℃样品,XRD有明显(002)衍射峰出现,在400～ 800 nm波长范围,透光率在88;以上,衬底温度300℃时,XRD衍射峰半高宽最小,晶粒尺寸大.TEM显示:衬底300℃晶粒尺寸最大,晶体发育好.在200℃掺铝ZnO薄膜,(002)峰不明显,有(101)峰出现.     

Optical investigations on the existence of phase transition in ZnO:Li thin films prepared by DC sputtering method

We investigated the effect of temperature on the absorption spectra of Zn_0.8Li_0.2O thin films (ZnO:Li), deposited at 573 K, in the wavelength range 190‐800 nm. The films were deposited on sapphire, MgO or quartz substrates by DC sputtering method. The results show a shift of the optical energy gap (E_g), with direct allowed transition type near the fundamental edge, to lower wavelengths as the temperature increases. The temperature rate of E_g changes considerably showing an anomaly around 320 K depending on type of substrate. The founded results indicated that replacement of Zn ions with Li ions induces a ferroelectric phase in the ZnO wurtzite‐type semiconductor. The exponential dependence of the absorption coefficient on the incident photon energy suggests the validity of the Urbach rule. (© 2007 WILEY ‐VCH Verlag GmbH & Co. KGaA, Weinheim)