Ag含量对TiO2薄膜光学性能和光催化性能影响

为了研究Ag含量对光催化效率的影响,采用电子 束沉积方法制备了Ag-TiO₂光催化剂,分别用X射 线衍射仪(XRD),紫外－可见光谱仪(UV-Vis),电子扫描显微镜(SEM),原子力显微镜 (AFM),X射线电子能谱 仪(XPS)等手段对晶体结构,光学性能和薄膜形貌以及元素价态元素组成等进行了表征.利用 太阳光,以甲基 橙(MO)为模型,分析了不同Ag含量薄膜的光催化效率.结果显示:Ag是以Ag⁰存在,Ag均匀而 牢固的分布在 TiO₂材料上;在300℃温度下,所形成的薄膜为无定形结构;沉积适 量的银,可以提高纳米二氧化钛光催化活性。     

激光预处理对HfO2光学薄膜微观性能的影响

研究了在1-on-1方式下激光预处理对HfO₂光学薄膜微观形貌、微观结构等性能的影响。实验采用薄 膜阈值能量的10%、50%%对HfO₂薄膜进行激光预处理,利用原子力显微镜(AFM )分别对预处理后薄膜表面 10μm和3μm×3μm的区域进行测 试,与预处理前相比,预处理后的薄膜所含杂质减少,薄膜表面锥状结构变得平 滑;利用X射线衍射(XRD)和X射线光电子能谱(XPS)分别对预处理后薄膜的晶态结 构和化学键以及价态进 行测试,与预处理前相比,预处理后薄膜的晶态结构、化学键及价态均没有发生变化;利用 XPS对预处理后薄膜所含 的成分进行测试,与预处理前相比,预处理后薄膜中所含的Hf单质减少,HfO₂增多。实验 结果表明,激光预处理具有抛光和氧化膜层的作用。     

TiO2基染料敏化太阳能电池的表面修饰及性能研究

采用水热法制备TiO₂浆料,用La(NO₃)₃溶 液浸泡TiO₂薄膜获得修饰电极。用X射线光电子能谱(XPS) 和扫描电子显微镜(SEM)对修饰电极的主要成分及形貌进行表征的结果显示,电极薄膜分为 上下两层,表 面包覆层粒径较大,为La₂O₃颗粒;下层颗粒粒径较小,为TiO₂颗粒。电流-电压测 试结果显示,与修饰 前相比,用La(NO₃)₃溶液浸泡30min获得的膜电极性能最优,使 开路电压和短路电流分别提高了6.8%和 18.5%。电化学阻抗谱(EIS)测试结果表明,相同偏压下,TiO₂/La ₂O₃电极界面复合电阻比TiO₂要大,说明 La₂O₃包覆层在一定程度上抑制了界面的电子复合,改善了电池的光电化学性能。     

退火温度对AZO薄膜场发射性能的影响

以纯度为99.95%、Al₂O₃为2wt.%的 ZnO-Al₂O₃金属氧化物为溅射靶材,采用射频(RF)磁控溅射的方法,在玻璃衬 底上制备Al掺杂ZnO(AZO)薄膜,研究其场发射特性和导电性能,并分析了不同的退火温度 对AZO薄膜的形貌、导 电及场发射性能的影响。采用原子力显微镜(AFM)及X射线衍射(XRD)对AZO薄膜表面 形貌与结晶特性 进行测试的结果表明,随着退火温度的升高,AZO薄膜的表面粗糙度随之增大,AZO薄膜的结 晶度变好;场发射 性能研究的结果表明,AZO薄膜的开启电场随着退火温度增加呈先减小后增大的趋势,当 退火温度为300℃时, AZO薄膜样品粗糙度最大,场发射性能最好,开启场强为2.8V/μm, 发光均匀性较好,亮度达到650cd/m²,导电 性能最好,电阻率为5.42×10－4 Ω·cm。     

新型CIGS阻挡层多横向界面Mo的特性及对器件性能的影响

采用磁控溅射方法,在不锈钢箔上制备多横向界 面Mo(M-Mo,multi-transverse interface Mo)和单横向界面Mo(S-Mo)薄 膜,并利用共蒸发三步法分别在M-Mo和S-Mo薄膜上制备Cu(In,Ga)Se₂(CIGS)薄膜及 器件。通过二次离子质谱仪(SIMS)、X射线衍射仪(XRD)和扫描电子显微镜(SEM)研究了不同 结构的Mo薄膜对CIGS影响。通过I-V测试,表征M-Mo和S -Mo作为背电极的CIGS电池电学性能。XRD结果显示,M-Mo和S-Mo 薄膜均以(110)为择优取向。SEM结果显示,M-Mo薄膜相对 于S-Mo,薄膜晶粒 较小,粗糙度较大。J-V测试结果显示,M-Mo薄膜作为背 电极的电池的开路电压Voc、短路电流J sc和填充因子(FF)均有所提高。     

用热蒸发法制备的Cu2ZnSnS4 薄膜的光电性能

在室温下用真空热蒸发法在玻璃基片上制备Sn/Cu/ZnS 前躯体膜层,然后对其在550C 下在硫气氛中硫化3小时以制得Cu₂ZnSnS₄ (CZTS) 多晶薄膜。对该薄膜进行X射线衍射（XRD）、能量色散X射线光谱（EDX）、紫外可见近红外分光光度计、霍尔测量系统和3D光学显微镜等分析测试。实验结果表明,当[Cu]/([Zn] [Sn]) =0.83和[Zn]/[Sn] =1.15时,该CZTS薄膜在光子能量范围在1.5 - 3.5 eV 时其吸收系数大于4.010₄cm_-1 ,直接带隙为1.47 eV。其载流子浓度、电阻率和迁移率分别为7.9710₁₆ cm_-3, 6.06 Ω.cm, 12.9 cm₂/(V.s), 导电类型为p型。因此,所制备出的CZTS 薄膜适合作为太阳电池的吸收层材料。     

退火Cu2O薄膜的结构及光学特性

采用射频(RF)磁控溅射单质金属铜(Cu)靶, 在O₂和Ar的混合气氛下制备了Cu₂O薄 膜,并在N₂气氛下对预沉积的Cu₂O薄膜进行快速光热退火(RTA)处理,研究了 衬底温度及退火温度对Cu₂O 薄膜的生长行为、物相结构、表面形貌及光学性能的影响。结果表明,衬底温度在300℃以 下预沉积的Cu₂O薄膜 为非晶薄膜,退火处理对Cu₂O薄膜的结晶行为有明显影响,在N₂气氛下对Cu₂O薄膜进 行退火处理不影响薄膜的物 相结构;预沉积和退火Cu₂O薄膜在650nm以下波长范围内均有较强 吸收,吸收强度随退火温度的增加而增强,薄 膜在400nm以下波长范围内出现两个由缺陷引起的中间带(IB)吸收行 为,快速热退火处理不能减少或消除薄膜沉积 过程中形成的缺陷态;退火处理影响薄膜的光学带隙Eg,预沉 积薄膜经600℃退火处理,E_g值增大了 0.26eV。     

MoO3修饰氧化石墨烯作为空穴注入层影响研究

研究了MoO₃修饰氧化石墨烯(GO)作为空穴注入层的影响。采用旋涂的方法制备了GO, 再真空蒸镀修饰层MoO₃,得到了空穴注入能力强和透过率高的复合薄膜。MoO₃的厚分 别采用0、3、5和8nm。通过优化MoO₃的厚度发现,当MoO₃的厚为5nm时,复合薄膜 的透过率达到最大值,在 550nm的光波长下透光率为88%,且此时采用 复合薄膜作为空穴注入层制备的结构为 ITO/GO/MoO₃(5nm)/NPB(40nm)/Alq₃(40nm)/LiF(1nm)/Al(100nm)的有机电致发光器件(OLED)性能 最佳。通过对OLED进一步的优化,改变Alq₃的厚度,分别取50、60和70nm,测量其电压 、电流、亮度、色坐标和电致发光(EL)光谱等参数发现,当Alq₃的厚为50nm时器件性能最 佳。最终制备了结构为ITO/GO/MoO₃(5nm)/NPB(50nm)/Alq₃(50nm)/LiF(1nm)/Al(100 nm)的OLED,在电压为10V时,最大电流效率达到5.87cd/A,与GO单独作为空穴注入层制备的器件相比,提高了50%。     

溅射压强对ITO/Cu2O复合膜结构和光学性能的影响

利用脉冲磁控溅射制备技术,以氧化铟锡(ITO)导电玻璃为基底,采用单质金属Cu 靶作为溅射靶,在O₂和Ar的混合气氛下沉积了Cu₂O薄膜。通过调控溅射压强,研 究了脉冲磁控溅射沉积法在不同溅 射压强下对Cu₂O薄膜的物相结构、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20∶90的气 氛条件下,在2～3Pa的溅射压强范围内,可获得纯相的Cu₂O薄膜;薄膜表面形貌依赖于 溅射压强,薄膜表面粗糙度的 均方根(RMS)值随溅射压强的增大而减小;在ITO上沉积Cu₂O 薄膜后,薄膜的光学吸收边红移至780 nm, ITO/Cu₂O复合膜的光谱吸收范围拓展至300～780 nm,复合膜的吸收强度随溅射压强的增 大而减小,光学带隙E_g 随溅射压强的增大而增大,E_g值为2.28～2.39eV。     

脉冲激光沉积Er:LiNbO3薄膜及1.54μm光致发光的研究

利用脉冲激光沉积(PLD)技术,通过双靶(Er₃O₂/LiNbO₃)交替与脉冲激光作用,在SiO ₂/Si 衬底上制备了c-轴择优取向的Er掺杂LiNbO₃(Er:LiNbO₃)薄 膜。用X射线衍射(XRD)、 场发射扫描电子显微镜(FESEM)、台阶仪及光致发光(PL)光 谱对制备的掺杂薄膜进行了表征。研究了衬底温度、O₂压及沉积时间对Er:LiNbO₃薄膜 结晶、表面形貌及 PL性能的影响。结果发现,衬底温度低于300℃时制备的Er:LiNbO 3薄膜为非晶膜,随衬底温度升高,薄膜出 现(006)衍射峰,并且其强度随衬底温度升高而增大;O₂压变化对 利用双靶沉积获得的Er:LiNbO₃薄膜择优 取向及(006)衍射峰强度影响不明显;沉积时间越长Er:LiNbO₃薄膜 中Er³⁺浓度越大,但结晶择优取向 变差;利用532nm波长激光泵浦,室温下,在1537nm波长处测得很强的光致荧光峰,而且沉积时间越长谱峰越尖锐强 度越大。     

VOLTE容灾机制研究及优化方案

_{本文首先对VOLTE现网网络结构及容灾机制进行研究分析,发现现存容灾机制中存在的缺点和不确定性,针对其中的问题,针对性地进行了深入研究和分析,创新的提出了1种快速容灾抢通方案,以达到提升VOLTE业务运维能力和用户业务感知的目的。}     

Calculation of energy band gaps in quaternary iii/v alloys

The dielectric theory of electronegativity is applied to the calculation of the compositional dependence of the energy band gap for quaternary III/V alloys of type A_l-xB_xC_1-yD_y and A_1-x-yB_xC_yD. The departure from linearity of E_G versus x and y is taken to be the sum of two terms, the intrinsic or virtual crystal term and the extrinsic term due to effects of aperiodicity which for one type of alloy may occur on both sublattices. Rather than simply treating the quaternary as an average of the bounding ternary systems, as has been common in the past, the intrinsic departure from linearity is calculated by assuming E_h,i,C, and D_av to vary linearly with x and y. The result is a smaller intrinsic deviation from linearity and a much better fit to existing data in the system Ga_1-xIn_xAs_1-y P_y. The calculation is also applied to three systems where no data exist but which are of great interest because of their potential application for the fabrication of lattice matched tandem solar cells: Ga_l-xA1_xAs_l-ySb_y. Ga_1-x-yA1_xIn_yAs, and GaAs_1-x-yP_xSb_y.     

Transport properties of thermoelectric materials for coolers

The Seebeck coefficient, thermal conductivity, electrical conductivity and Hall coefficient of cooler grade, p-and n-type ternary alloys of Bi₂Te₃-Sb₂Te₃-Sb₂Se₃ were measured between 10 and 300 K. Between 300 K and about 150 K the temperature dependence of the transport properties can be explained by assuming nondegeneracy and a lattice scattering mechanism. The difference between the temperature dependence of the Hall effect in n-and p-type alloys can be explained by the presence of sub-bands of light and heavy holes in the valence band of p-type alloys.     

Low pressure metalorganic chemical vapor deposition of InP and related compounds

The low pressure metalorganic chemical vapor deposition epitaxial growth and characterization of InP, Ga_0.47In_0.53 As and Ga_xIn_1-xAs_yP_1-y, lattice-matched to InP substrate are described. The layers were found to have the same etch pit density (EPD) as the substrate. The best mobility obtained for InP was 5300 cm² V⁻¹S⁻¹ at 300 K and 58 900 cm² V⁻¹ S⁻¹ at 77₂K, and for GaInAs was 11900 cm² V⁻¹ S⁻¹ at 300 K, 54 600 cm² V⁻¹ S⁻¹ at 77 K and 90 000 cm V⁻¹S⁻¹ at 2°K. We report the first successful growth of a GaInAs-InP superlattice and the enhanced mobility of a two dimensional electron gas at a GaInAs -InP heterojunction grown by LP-MO CVD. LP MO CVD material has been used for GaInAsPInP, DH lasers emitting at 1.3 um and 1.5 um. These devices exhibit a low threshold current, a slightly higher than liquid phase epitaxy devices and a high differential quantum efficiency of 60%. Fundamental transverse mode oscillation has been achieved up to a power outpout of 10 mW. Threshold currents as low as 200 mA dc have been measured for devices with a stripe width of 9 um and a cavity length of 300 um for emission at 1.5 um. Values of T in the range 64–80 C have been obtained. Preliminary life testing has been carried out at room temperature on a few laser diodes (λ = 1.5μm). Operation at constant current for severalthousand hours has been achieved with no change in the threshold current.     

Formation of secondary phases during crystal growth of Pb5Ge3O11

Studies of secondary phases formed during the Czochralski growth of lead germanate crystals (Pb₅Ge₃O₁₁) show that these phases form inclusions in the crystal, thereby reducing its optical quality, and can also cause twinning and cracking. Results of differential thermal analysis, energy dispersive X-ray fluorescence analysis, and X-ray diffraction studies of secondary phases are presented. The narrow stability range for Pb₅Ge₃O₁₁ shown in the phase diagram, the thermal instability of this compound, and its pronounced supercooling during crystallization suggest that equilibrium conditions are difficult to sustain and that other compounds of the PbO-GeO₂ family may form, although Pb₅Ge3O₁₁ is melting congruently. It is shown that Pb₃GeO₅ and PbGeO₃, which are both reported to melt congruently, can crystallize during the growth of Pb₅Ge₃O₁₁ forming inclusions in the crystal. The successful synthesis of these three compounds is reported. The compound Pb₃Ge₂O₇, reported in the literature, is identified as a mixture of Pb₅Ge₃O₁₁ and PbGeO₃. Experimental conditions are presented for growing single phase Pb₅Ge₃O₁₁ crystals of uniform composition and high optical quality. This paper is based on a presentation at the Conference on Preparation and Properies of Electronic Materials, Princeton, N. J., August 1975.     

Characterization of a rapid thermal anneal TiNxOy/TiSi2 contact barrier

In this paper, the physical and electrical properties of a TiN_xO_y/TiSi₂ dual layer contact barrier are reported. The TiN_xO_y/TiSi₂ barrier was formed by rapidly annealing a Ti thin film on Si in an N₂ ambient. During this process, the Ti film surface reacts with N₂ to form a TiN_xO_y skin layer and the bulk of the Ti film reacts with Si to form an underlying TiSi₂ layer. The influences of rapid thermal anneal (RTA) conditions on the TiN_xO_y layer were investigated by varying the RTA temperature from 600 to 1100° C and cycle duration from 30 to 100 s. It is found that the resulting TiN_xO_y and TiSi₂ layer thicknesses are dependent on RTA temperature and the starting Ti thickness. For a starting Ti thickness of 500Å, 150Å thick TiN_xO_y and 800Å thick TiSi₂ are obtained after an RTA at 900° C for 30 s. The TiN_xO_y thickness is limited by a fast diffusion of Si into Ti to form TiSi₂. When a Ti film is deposited on SiO₂, Ti starts to react with SiO₂ from 600° C and a significant reduction of the SiO₂ thickness is observed after an RTA at 900° C. The resulting layer is composed of a surface TiN_xO_y layer followed by a complex layer of titanium oxide and titanium suicide. In addition, when Ti is depos-ited on TiSi₂, thicker TiN_xO_y and TiSi₂ layers are obtained after RTA. This is because the TiSi₂ layer retards the diffusion of Si from the underlying substrate into the Ti layer. NMOSFETs were fabricated using the TiN_xO_y/TiSi₂ as a contact barrier formed by RTA at 900° C for 30 s and a significant reduction of contact resistance was obtained. In addition, electromigration test at a high current density indicated that a significant improvement in mean time to failure (MTF) has been obtained with the barrier.     

The effect of Tl2Te3 on the properties of the solid solution (Sb2Te3)0.75.(Bi2Te3)0.25

The effect on transport properties of the addition of 0.5-5% Tl₂Te₃ to p-type solid solutions of antimony and bismuth tellurides was studied. It was found that the addition of Tl₂Te₃ caused a lessening of the increase of hole concentration as low temperatures were approached, resulting in a slower decrease of the Seebeck coefficient with a decrease in temperature. In partial fulfillment of M.Sc. degree, Hebrew University, Jerusalem. Permanent address, Dept. of Inorganic and Analytical Chemistry, Hebrew University, Jerusalem.     

Horizontal unseeded vapor growth of Iv-Vi compounds and alloys

Large, high-quality crystals of various Pb-salt compounds and alloys have been grown from the vapor by a horizontal, unseeded, closed-tube method. The optimum growth conditions have been experimentally determined. The crystalline imperfections and electrical properties of the crystals were examined. In a series of growth experiments on PbTe, the source materials were prepared by adding small quantities of Pb to much larger quantities of zone-melted PbTe. This method makes it possible to control the source and as-grown crystal compositions for excess Pb or Te concentrations in the 10¹⁸/cm³ range. From the results of these experiments it was found that the composition of zone-melted PbTe (i. e., the maximum-melting point composition of PbTe) corresponds to a hole concentration of approximately 1 x l0¹⁹/cm³. This work was sponsored by the Department of the Air Force.     

Al2O3/GaSb p-MOSFET器件电学性质模拟

利用泊松方程和连续性方程对Al2O3/GaSb p-MOSFET进行二维数值分析,研究其在高场和载流子速度饱和下的电学特性以及漏极电流的开关电流比.与实验研究相对比,沟道长度为0.75 μm的GaSb p-MOS器件获得漏极电流最大为61.2mA/mm.改变沟道长度和GaSb衬底的掺杂浓度,由于高k介质栅电容效应和低阈值电压,漏极电流变化不大.在理想条件下,该器件获得超过三个数量级的漏极开关电流比以及较低的夹断漏电流(10-15A/μm).结果表明,基于高k介质的GaSb MOSFET是III-V族p沟道器件良好的候选材料.     

The effect of trimethylaluminum concentration on the incorporation of P In AlxGa1−xPyAs1−y grown by organometallic vapor phase epitaxy

The organometallic vapor phase epitaxial (OM-VPE) growth of Al_xGa_1-xP_yAs_1-y on graded GaP_yAs_1-yGaAs in the compositional range 0 < x < 0.9 and 0 < y < 0.6 is reported. It is found that composition control can be easily achieved, and that the vapor phase ratio of trimethylaluminum to trimethylgallium strongly influences the incorporation of P in the solid. A model is developed which explains this in terms of competing reaction rates. The model gives a good fit to the experimental data.