基片温度对基于Bi1.5Zn1.0Nb1.5O7栅绝缘层的ZnO基TFT性能的影响

在不同基片温度(RT、300、400、500和600℃)下,采用射频磁控溅射法制备了ZnO薄膜和BZN薄膜.研究表明,所制备的BZN薄膜拥有非晶态结构,ZnO薄膜具有c轴择优取向,在基片温度为500℃时,获得低的漏电流(10-7 A/cm2),比RT时的漏电流(10-4 A/cm2)低三个数量级.将所制备的ZnO薄膜和BZN薄膜分别作为ZnO-TFT的有源层和栅绝缘层,研究表明,在基片温度为500℃时,提高了器件性能,所取得的亚阈值摆幅(470 mV/dec.)是RT时的亚阈值摆幅(1 271 mV/dec.)的三分之一;界面态密度(3.21×1012 cm-2)是RT时的界面态密度(1.48×1013 cm-2)的五分之一.     

Si基Sr1.8Ca0.2NaNb5O15薄膜的合成及光学特性研究

利用溶胶-凝胶法,在Si(001)单晶衬底上逐层生长四方钨青铜结构的Sr1.8Ca0.2NaNb5O15(SCNN)薄膜。利用X射线衍射(XRD)仪、扫描电子显微镜(SEM)和原子力显微镜(AFM)等技术研究了薄膜的微结构,结果表明,SCNN薄膜在厚度较小的状态下可呈现出明显的(001)择优取向,而随着厚度的增加择优取向受到抑制,颗粒尺寸增大,薄膜的多晶态的趋势增强。然后通过测量薄膜在400~780nm光谱范围内的反射率曲线,采用Sellmeier色散公式分析折射率非均匀性的影响,通过改进的单纯形法计算拟合出SCNN薄膜的折射率和厚度,其中厚度的结果利用SEM加以验证,而折射率的变化则与薄膜结晶态的变化保持一致。     

ZnO掺杂对CaCu3Ti4O12陶瓷介电性能的改善及其机理研究

现代科技的发展对于电子器件的小型化有着越来越高的要求,CaCu₃Ti₄O₁₂(CCTO)是一种被认为具有开发潜力的介电材料,然而其介电损耗过高阻碍其投入应用,因此采用溶胶凝胶法制备了不同ZnO掺杂含量的CCTO陶瓷。使用了XRD、SEM、宽频介电谱仪和高阻计对所有样品的相组成、微观形貌和介电性能进行了表征,探讨了不同ZnO掺杂量对CCTO陶瓷介电性能的影响。结果表明,ZnO掺杂的CCTO陶瓷保持了单一的CCTO相结构和良好的晶粒分布,击穿特性有所增强。其中,ZnO掺杂浓度为摩尔分数6%的CCTO陶瓷,其相对介电常数为7471(1 kHz),tanδ最小值为0.018,并且在较宽的频率范围内(10¹～10⁵ Hz)都具有较低的tanδ值(<0.05),击穿场强为2.95 kV/cm。分析表明,tanδ的改善主要是由于晶界电阻的增强和晶界弛豫极化损耗的降低所引起。ZnO掺杂的CCTO陶瓷具有良好的介电性能,对加快CCTO的广泛应用具有重要意义。     

Ti-Al共掺ZnO薄膜的应力、结构和光电性能研究

利用直流磁控溅射工艺,在水冷玻璃衬底上成功沉积出了高透光、低电阻率的Ti-Al共掺ZnO(TAZO)透明导电薄膜.X射线衍射(XRD)研究结果表明,TAZO薄膜为具有c轴择优取向的六角纤锌矿结构多品薄膜.研究了TAZO薄膜的应力、结构以及光电性能与薄膜厚度的关系,结果表明.当薄膜厚为531 nm时,薄膜晶格畸变最小,具...     

衬底温度对Na-Mg共掺ZnO薄膜光学性能的影响

采用超声喷雾热解法,以石英玻璃为衬底,以乙酸 锌(Zn(CH₃COO)₂·2H₂O)、硝酸镁(Mg(NO₃)₂·6H₂O) 和醋酸钠(CH₃COONa·3H₂O)为前驱体溶液,在不同衬底温 度(480～560℃)下制备Na-Mg共掺杂ZnO薄膜。通过X-射线衍射(X RD)、扫描电子显微镜(SEM)、 光致发光(PL)谱和紫外-可见(UV-Vis)分光光度计等表征手段对样品的晶格结构 、表面形貌、PL性能 和透过率进行了研究。结果表明,衬底温度对薄膜结构和光学特性影响显著,当衬底温度为 500 ℃时制备的 Na-Mg共掺杂ZnO薄膜的c轴择优最明显,表面形貌更加致密,结 晶质量最好,PL性能最佳。     

掺Al对ZnO薄膜发光性能的调控作用

采用溶胶-凝胶法，在玻璃上制备了不同掺Al浓度的ZnO薄膜。x射线衍射（XRD）结果表明，所制备的薄膜具有c轴择优取向，随着掺Al浓度的增加，（002）峰向低角移动，峰强逐渐减弱。探讨了掺Al对ZnO薄膜发光性能的调控作用，薄膜的透射谱表明：通过改变掺Al浓度，可以提高ZnO薄膜的紫外光透过率，使其吸收边向短波长方向的移动被控制在一定的范围内，从而使薄膜禁带宽度连续可凋；薄膜的光致发光（PL）谱显示：纯ZnO薄膜的PL谱是由紫外激子发光和深能级缺陷发光组成，通过掺Al有助于减少薄膜的缺陷，减弱深能级的缺陷发光，同时紫外带边发射的峰位向高能侧蓝移，与吸收边缘移动的结果相吻合，由紫外发光峰位获得的光禁带与通过透射谱拟合得到的光禁带基本一致。     

Nd:Lu3Al5O12晶体光谱与激光性能研究

采用提拉法生长Nd掺杂原子数分数为1%的高质量的Nd:Lu3Al5O12(Nd:LuAG)晶体。对晶体的光谱性能进行了表征。研究发现,Nd:LuAG晶体与相同掺杂浓度的Nd:YAG晶体均具有相似的峰形和峰位,但特征吸收峰和荧光峰均发生了1nm的红移现象。Nd:LuAG晶体具有比Nd:YAG和Nd:GGG晶体更长的荧光寿命和更宽的吸收线宽。在抽运功率为900mW的钛宝石激光器抽运下,Nd:LuAG晶体获得了420mW的连续激光输出,斜率效率为47.5%,激光抽运阈值为22mW。     

退火温度对ZnO/PZT薄膜结构及电阻率的影响

采用射频反应磁控溅射法在Pb(Zr0.52Ti0.48)O3(PZT)/Pt/Ti/SiO2/Si基片上制备了ZnO薄膜,利用X线衍射仪(XRD)、原子力显微镜(AFM)、霍尔效应测试系统等对不同退火温度下制备薄膜的结构、形貌及电阻率等进行了分析表征。结果表明,退火温度600℃的ZnO薄膜(002)择优取向较好,晶粒大小均匀,表面平整致密。随着退火温度的增大,电阻率先下降后升高,600℃时ZnO薄膜电阻率达最小。     

缓冲层对太阳电池用ZnO:B薄膜结构及其光电性能的影响

通过优化ZnO缓冲层(buffer layer),有效地改善了由金属有机化学气相沉积(MOVCD)法制备的ZnO:B薄膜的光电特性。结果表明,"富氧"的缓冲层有效增加了ZnO:B-TCO的近红外区域透过率,使其更适应宽光谱薄膜太阳电池的发展要求。经过优化的ZnO:B,"类金字塔"状晶粒尺寸约300～500nm,波长550nm处绒度(haze)为10.8%,薄膜电子迁移率为20.7cm2/Vs,电阻率为2.14×10-3Ω.cm,载流子浓度为1.41×1020cm-3,且在400～1 500nm波长范围内的平均透过率为83%(含2mm厚玻璃衬底)。     

Bi1.5Zn1.0Nb1.5O7/Ba0.5Sr0.5TiO3复合薄膜介电性能的频率特性研究

采用射频磁控溅射法在蓝宝石基片上制备了Bi1.5Zn1.0Nb1.5O7(BZN)/Ba0.5Sr0.5TiO3(BST)双层复合薄膜,并研究了该薄膜在100 kHz~6 GHz频率范围内的介电性能。研究结果表明,BZN/BST复合薄膜的介电性能具有良好的频率稳定性。该复合薄膜的介电常数在研究的频率范围内基本与频率无关;其介电损耗在频率低于1 GHz时与频率无关,在频率高于1 GHz时随频率的上升而略微增大;薄膜在研究的频率范围内具有稳定的介电调谐率。     

Effects of excess Bi concentration, buffered Bi2O3 layer, and Ta doping on the orientation and ferroelectricity of chemical-solution-deposited Bi3.25La0.75Ti3O12 films

Effects of excess Bi concentration, buffered Bi₂O₃ layer, and Ta doping on the orientation and ferroelectricity of chemical-solution-deposited (CSD) Bi_3.25La_0.75Ti₃O₁₂ (BLT) films on Pt/SiO₂/Si(100) were studied. The optimum concentration of excess Bi added to the BLT films to achieve a larger remanent polarization (2Pr) was 10 mol.%. The buffered Bi₂O₃ layers could reduce the temperature for c-axis-oriented growth of BLT films from 850°C to 700°C. However, two-step annealing, i.e., first annealed at 650°C and then annealed at a temperature of 700–850°C, could effectively suppress the c-axis-oriented growth and thus improve the 2Pr of BLT films. The improvement of the 2Pr of BLT films can be explained in terms of the large polarization along the a-axis orientation and buffered Bi₂O₃ layers, which compensate the BLT films for Bi evaporation during annealing. The Ta doping can induce two contrary effects on the 2Pr of BLT films. For the (Bi_3.25La_0.75)(Ti_3−xTa_x)O₁₂ (BLTTx) films with x=0.005, the effect of a decrease of oxygen vacancies would be dominant, resulting in the improvement of 2Pr. Because the Ta concentration (x) in the BLTTx films exceeds 0.01, the effect of a decrease of grain size would become dominant, resulting in the degradation of 2Pr.     

基于BGO晶体的磁光式冲击电流传感器及其信号处理

本文提出了一种基于偏振检测原理,采用Bi₄Ge ₃O₁₂(BGO)晶体的磁光式冲击电流传感器,可以测 量幅值范围10 kA到90 kA的8/20 μs冲击电流。由于冲击电流的持续时间极短,光源功率漂移对测量的干 扰可以忽略,偏振检测结构可以保证测量结果的正确性。由于BGO晶体具有维尔德常数大的 突出优点,传 感器可以获得较高的测量灵敏度。利用小波分解法,并以信噪比(SNR)和平滑度(SR) 作为去噪结果的 评价标准,确定了合适的小波函数(Daubechies Db7)和分解层数(5层),有效地去除了 测量结果中的干 扰噪声。此电流传感器的灵敏度达到0.262°/ kA,具有较好的线性度,且冲击电流幅值的测量误差控制在 ±5%以内。本文所提出的电流传感器具有结构简单、性能可靠的优点,适用于雷电流测试、 核物理实验和高功率脉冲激光研究等恶劣环境下的冲击电流测量。     

Effects of annealing schedule on orientations of Bi3.2Nd0.8Ti3O12 ferroelectric films prepared by metalorganic solution deposition

Fatigue-free Bi_3.2Nd_0.8Ti₃O₁₂ ferroelectric thin films were successfully prepared on p-Si(1 1 1) substrate using metalorganic solution deposition process. The orientation and formation of thin film under different annealing schedules were studied using XRD and AFM. XRD analysis indicated that (2 0 0)-oriented films with degree of orientation of I₍₂₀₀₎/I₍₁₁₇₎ = 2.097 and 0.466 were obtained by preannealing the film at 400 °C for 10 min followed by rapid thermal annealing at 700 °C for 3 min, 10 min and 20 min, respectively, (0 0 8)-oriented film with degree of orientation of I₍₀₀₈₎/I₍₁₁₇₎ = 1.706 were obtained by rapid thermal annealing the film at 700 °C for 3 min without preannealing, and (0 0 8)-oriented film with degree of orientation of I₍₀₀₈₎/I₍₁₁₇₎ = 0.719 were obtained by preheating the film from room temperature to 700 °C at 20 °C/min followed by annealing for 10 min. The a-axis and c-axis orientation decreased as increase in annealing time due to effects of (1 1 1)-oriented substrate. AFM analysis further indicated that preannealing at 400 °C for 10 min followed by rapid thermal annealing at 700 °C for 3 min resulted in formation of platelike crystallite parallel to substrate surface, however rapid thermal annealing at 700 °C for 3 min without preannealing resulted in columnar crystallite perpendicular to substrate surface.     

Bi_2O_3和Sb_2O_3的预复合对ZnO压敏电阻性能的影响

采用固相法对Bi2O3和Sb2O3进行了预复合,并研究了不同比例的Bi2O3与Sb2O3预复合对ZnO压敏电阻致密度,晶粒结构和电学性能的影响。结果表明:当Bi2O3与Sb2O3的摩尔比为0.7:1.0时,ZnO压敏电阻的综合性能最优,其晶粒生长得最为均匀致密,电位梯度达到361V/mm,非线性系数为86,漏电流密度为7×10–8A/cm2;另外,在耐受5kA电流下的8/20μs脉冲电流波后,其残压比和压敏电压变化率分别为2.6和2.5%。     

On the profile of frequency dependent series resistance and surface states in Au/Bi4Ti3O12/SiO2/n-Si(MFIS) structures

The frequency dependent capacitance-voltage (C-V) and conductance-voltage (G/ω-V) characteristics of the metal-ferroelectric-insulator-semiconductor (Au/Bi₄Ti₃O₁₂/SiO₂/n-Si) structures (MFIS) were investigated by considering series resistance (R_s) and surface state effects in the frequency range of 1 kHz-5 MHz. The experimental C-V-f and G/ω-V-f characteristics of MFIS structures show fairly large frequency dispersion especially at low frequencies due to R_s and N_ss. In addition, the high frequency capacitance (C_m) and conductance (G_m/ω) values measured under both reverse and forward bias were corrected for the effect of series resistance to obtain the real capacitance of MFIS structures. The R_s-V plots exhibit anomalous peaks between inversion and depletion regions at each frequency and peak positions shift towards positive bias with increasing frequency. The C⁻²-V plot gives a straight line in wide voltage region, indicating that interface states and inversion layer charge cannot follow the ac signal in the depletion region, but especially in the strong inversion and accumulation region. Also, it has been shown that the surface state density decreases exponentially with increasing frequency. The C-V-f and G/w-V-f characteristics confirm that the interface state density (N_ss) and series resistance (R_s) of the MFIS structures are important parameters that strongly influence the electrical properties of MFIS structures.     

（Bi4—x,Lax）Ti3O12粉体的溶胶—凝胶制备技术研究

采用溶胶－凝胶（Sol-Gel）技术,以硝酸铋、硝酸镧和钛酸丁酯为原料,制备了掺镧钛酸铋（Bi3.6,La0.4）Ti3O12（简记为BLT）粉体。利用DTA、XRD以及激光光散射粒度分析等手段分析了粉体的固相反应、结构和颗粒度,结果表明,BLT初始粉体在730℃左右发生固相反应,生成BLT颗粒;730℃以下烧结的粉体为含立方（Bi,La)12TiO20相和正交（Bi3.6,La0.4）Ti3O12相的混合物,平均颗粒度为60nm左右;730℃以上烧结的粉体为完全正交结构的BLT多晶颗粒体,平均颗粒度约为500nm;利用Sol-Gel技术,可以制备纳米级、分散良好、分布一致的BLT粉体,这对BLT新型压电陶瓷的制备具有重要意义。     

PbO和Bi_2O_3-Li_2CO_3助烧剂对Pb(Zr_(0.9)Ti_(0.1))O_3厚膜热释电性能的影响

采用丝网印刷工艺制备了Pb(Zr0.9T0.1)O3(PZT)厚膜,研究了过量PbO和Bi2O3-Li2CO3共同助烧对PZT厚膜低温烧结特性、微观结构、相构成以及介电和热释电性能的影响。结果表明:随着过量PbO及Bi2O3-Li2CO3添加量的增加,PZT厚膜的烧结温度和晶粒尺寸均逐渐降低。当PbO过量6.4%(质量分数)、Bi2O3-Li2CO3添加量为5.4%(质量分数)时,PZT厚膜可在900℃低温下致密成瓷,且其热释电系数和探测率优值均得到大幅提高;所得样品在30℃时的热释电系数为10.6×10–8C.cm–2.K–1,探测率优值为8.2×10–5Pa–1/2。     

稀土元素对KNdP_4O_(12)激光晶体的影响

用蒸发溶液法从磷酸溶液中生长出14种KNd_(0.9)Ln_(0.1)P_4O_(12)晶体(其中Ln=La、Ce、Pr、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu或Y)。测定了它们的晶体结构、红外光谱、吸收光谱、荧光光谱和荧光寿命,计算了晶格常数,观察到掺入Ln~(3+)后对KNdP_4O_(12)晶体的影响。     

Solvothermal synthesis of Bi2O3/BiVO4 heterojunction with enhanced visible-light photocatalytic performances

Novel, three-dimensional, flower-like Bi2O3/BiVO4 heterojunction photocatalysts have been prepared by the combination of homogeneous precipitation and two-step solvothermal method followed by thermal solution of NaOH etching process. The as-obtained samples were fully characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, Brunauer-Emmett-Teller surface area, and UV-vis diffusereflectance spectroscopy in detail. The crystallinity, microstructure, specific surface area, optical property and photocatalytic activity of samples greatly changed depending on solvothermal reaction time. The photocatalytic activities of samples were evaluated on the degradation of methyl orange (MO) under visible-light irradiation. The Bi2O3/BiVO4 exhibited much higher photocatalytic activities than pure BiVO4 and conventional TiO2 (P25). The result revealed that the three-dimensional heterojunction played a critical role in the separation of the electron and hole pairs and enhancement of the interfacial charge transfer efficiency, which was responsible for the enhanced photocatalytic activity.     

Effect of annealing temperature of Bi1.5Zn1.0Nb1.5O7 gate insulator on performance of ZnO based thin film transistors

The bottom-gate structure ZnO based thin film transistors (ZnO-TFTs) using Bi_1.5Zn_1.0Nb_1.5O₇ (BZN) thin films as gate insulator were fabricated on Pt/SiO₂/Si substrate by radio frequency magnetic sputtering. We investigated the effect of annealing temperature at 300, 400, and 500℃ on the performance of BZN thin films and ZnO-TFTs. XRD measurement confirmed that BZN thin films were amorphous in nature. BZN thin films annealed at 400℃ obtain the high capacitance density of 249 nF/cm², high dielectric constant of 71, and low leakage current density of 10^-7 A/cm² on/off current ratio and field effect mobility of ZnO-TFTs annealed at 400℃ are approximately one order of magnitude and two times, respectively higher than that of ZnO-TFTs annealed at 300℃. When the annealing temperature is 400℃, the electrical performance of ZnO-TFTs is enhanced remarkably. Devices obtain a low sub-threshold swing of 470 mV/dec and surface states density of 3.21×10¹²cm^-2.