利用ICP法测定ZnMgO薄膜的Mg组分

利用电感耦合等离子体(ICP)装置对分子束外延(MBE)法在Sapphire衬底上生长的Zn_1-xMg_xO薄膜的Mg组分进行了测试. 经理论分析，得到使用1次和2次检量式所确定的Zn_1-xMg_xO薄膜中的Mg组分的差异. 将采用1次检量式的ICP测定与EPMA测定结果进行对照，表明当Mg组分x≤0.5时二者的测试结果相当一致，由此证明ICP测试结果的正确性. 关键词： ZnMgO薄膜 Mg组分 分子束外延(MBE) 电感耦合等离子体(ICP)     

溶胶-凝胶法制备Zn1-xMgxO薄膜及其发光性质

采用溶胶-凝胶工艺在玻璃衬底上制备了Zn1-xMgxO(x=0.1,0.2,0.3,0.4,0.5,0.6,0.7)薄膜。X射线衍射(XRD)谱测试结果发现:在0.10.3时出现MgO立方相。薄膜光致发光谱研究表明紫外发光峰随Mg含量的增加向短波方向移动,且随着退火温度的升高发生明显蓝移,禁带宽度增大。但是退火温度为590℃的样品较560℃样品的发光峰出现红移。     

Zn1-xMgxO薄膜p型导电和光学性能

采用超声喷雾热分解(Ultrasonic Spray Pyrolysis,USP)方法,以醋酸锌、醋酸镁、醋酸铵、氯化铝的混合水溶液为前驱溶液,在单晶Si(100)衬底上制备了ZnO,Zn_0.81Mg_0.19O,N-Al共掺杂ZnO和N-Al共掺杂Zn_0.81Mg_0.19O薄膜。以X射线衍射(XRD)、场发射-扫描电镜(FE-SEM)、霍尔效应(Hall-effect)、光致发光(Photoluminescence,PL)谱等手段研究了薄膜的晶体结构、表面形貌、电学性能、光学性能和带隙变化。电学测试结果表明,未掺杂ZnO及Zn_0.81Mg_0.19O薄膜为n型导电;而N-Al共掺杂ZnO和N-Al共掺杂Zn_0.81Mg_0.19O薄膜呈p型导电。Zn_0.81Mg_0.19O和N-Al共掺杂Zn_0.81Mg_0.19O(p型)薄膜在维持ZnO纤锌矿结构的前提下,光学带隙随Mg掺杂量增加而增大。初步结果显示,优化工艺参数下通过Mg掺杂制备光学带隙可调的p型Zn_0.81Mg_0.19O薄膜,对于试制Zn_1-xMg_xO基同质p-n结、短波长(紫外、深紫外)器件等方面有重要意义。     

Mg含量对Mg_xZn_(1-x)O∶Ga薄膜电学性质的影响

通过金属有机物化学气相沉积法制备了不同Mg组分的MgxZn1-xO∶Ga(x=0,0.03,0.14)薄膜。透射谱中MgxZn1-xO∶Ga薄膜的光学带隙随x增大而出现的蓝移证实了Mg在Zn O晶格中的替位掺入。薄膜上金叉指电极间的变温I-V曲线显示,在同等温度下,Ga掺杂MgxZn1-xO薄膜的电阻率随着x值的增大而逐渐升高。这是由于Mg组分增大使材料的导带底显著上升,Ga的施主能级深度增大,导致n型载流子浓度降低。根据I-V曲线计算了270 K温度下MgxZn1-xO∶Ga薄膜的浅能级施主深度。与x=0,0.03,0.14对应的施主能级深度分别为45.3,58.5,65 me V,说明随着薄膜Mg含量的升高,Ga的施主能级深度有增加的趋势。     

Zn1-xMgxO薄膜的光致发光特性研究

采用脉冲激光沉积方法在单晶Si(100)衬底上制备出c轴取向的Zn1-xMgxO单晶薄膜,通过荧光光谱仪研究了薄膜的光致发光特性.实验结果表明,Mg含量增加,Zn1-xMgxO单晶薄膜的紫外发光峰蓝移,发光峰强度减弱,缺陷发光强度增强.同时发现,由于Mg的掺杂,引入了一些束缚能较大的局域束缚态.对于氧气氛下制备的样品,实验发现紫外峰和绿光带发光峰同时增强,但是R值减小,紫外峰红移.对绿光发光机理研究发现,绿光发光带主要与锌空位、氧间隙(Oi)或锌位氧(OZn)等缺陷有关,它是由多个缺陷发光峰组成,各缺陷发光峰强度相对变化导致了绿光发光带的整体移动.     

分子束外延法在Sapphire衬底上生长的Zn1-xMgxO薄膜折射率及厚度的测试

利用偏振光椭圆率测量仪对分子束外延(MBE)法在Sapphire衬底上生长的Zn1-xMgxO薄膜的薄膜折射率和厚度进行了测试.结合ICP法测得的薄膜中的Mg组成量,经数值拟合,导出表征薄膜厚度与薄膜生长条件、薄膜折射率与薄膜中的Mg组成量之间关系的曲线,为MBE法在Sapphire衬底上生长Zn1-xMgxO薄膜时控制薄膜厚度以及在制作Zn1-xMgxO薄膜的波导时控制薄膜的折射率提供了理论依据.     

Third-order optical nonlinearities of Zn1-xMgxO thin films

The Zn1-xMgxO thin films were deposited on sapphire substrates by reactive electron beam evaporation deposition (REBED). The X-ray diffraction (XRD) measurement demonstrates that these films undergo phase transition from hexagonal to cubic with increasing the Mg concentration. Absorption coefficients at 532 nm of the samples were obtained from the absorption spectra. Using optical Kerr effect, the thirdorder susceptibilities of the ternary films over a wide range of Mg concentrations were determined. The magnitude of x(3) of the ternary Zn1-xMgxO films is order of 10-11 esu at λ = 532 nm. The sample with phase mixture of both hexagonal and cubic structures shows the largest third-order susceptibility. The difference observed in the magnitude of x(3) of Zn1-xMgxO films is attributed to the different microstructures of the ternary films, such as crystalline phase separation and crystal grains that enhance stimulated scattering.     

硅衬底上Zn1-xMgxO薄膜的结构与光学性质

采用脉冲激光法（PLD）在Si衬底上沉积Zn1-xMgxO薄膜.x射线衍射(XRD)表明薄膜为c轴取向，（002）峰的半高宽仅为0.211°，且没有MgO的相偏析.透射电子显微镜可以清楚看到Zn1-xMgxO薄膜的c轴择优取向.在选区电子衍射图中可以看到Zn1-xMgxO结晶薄膜整齐的衍射斑点.室温下对Zn1-xMgxO薄膜进行了光致荧光光谱分析，发现其带边发射峰相对ZnO晶体有0.4eV的蓝移，带边发射峰与杂质发射峰的强度之比高达159.Zn1-xMgxO结晶薄膜质量良好，显示了应用于光电器件的潜力. 关键词： Zn1-xMgxO合金薄膜 硅衬底 脉冲激光沉积法 c轴取向 光致荧光光谱     

Ultraviolet Luminescence in Mg0.12Zn0.88O Alloy Films

We investigate the origin of ultraviolet （UV） emission from Mg0.12 Zn0.88 O alloy thin films with a wurtzite structure fabricated on c-plane Al2O3 substrates by plasma assisted molecular beam epitaxy. At room temperature, the absorption edge and UV emission band of the Mg0.12Zn0.88O film shift to high-energy side compared with ZnO films. Temperature dependence of the photoluminescence spectra shows that the UV emission is composed of free exciton and neutral donor bound exciton emissions. Two-step dissociation processes of the UV emission are observed with the increasing temperature. The thermal quenching mechanism is attributed to the dissociation of the free exciton from the neutral donor bound exciton in the low temperature region and the dissociation of free electron and hole from the free exciton in the high temperature region.     

制备工艺对Zn1-xMgxO薄膜结构及光学性能的影响

采用脉冲激光沉积(PLD)方法在单晶Si(100)衬底上沿c轴方向生长单晶Zn1-xMgxO薄膜,通过X射线衍射(XRD)、原子力显微镜(AFM)、扫描电镜(SEM)和荧光光谱(PL)研究了膜厚、Mg含量、退火温度及氧气氛等制备工艺对Zn1-xMgxO薄膜的结构、形貌和光学性质的影响.实验结果表明,Mg含量x≤0.15时, Zn1-xMgxO保持六角纤锌矿结构,0.25≤x≤0.35时为立方结构,经过600℃退火之后,Zn0.75Mg0.25O转化为六角纤锌矿结构;后续退火有利于晶粒长大,一定的氧气氛也有利于减少晶体缺陷和薄膜的c轴应力,但是过量的氧气容易与Mg元素结合形成MgO,不利于ZnO 六角纤锌矿结构的生长.对Zn0.925Mg0.075O薄膜进行荧光光谱分析,分析结果表明缺陷发光峰主要与锌空位、锌位氧(Ozn)或氧间隙(Oi)等缺陷有关,退火可以使紫外发射峰蓝移.     

Al和N共掺对Zn_(1-x)Mg_xO光学性质的影响

基于密度泛函理论第一性原理方法计算了Al和N共掺对Zn1-xMgxO在紫外光波段和可见光波段光学性质的影响.计算结果表明:光学性质变化主要发生在低能区,在高能区光学性质基本保持不变.介电函数虚部、吸收光谱和消光系数计算表明,Al和N共掺后Zn1-xMgxO的光学吸收边产生红移,对部分紫外光和可见光的吸收增强.介电函数实部和反射光谱计算表明,Al和N共掺后Zn1-xMgxO的反射峰强度增大,静态介电常数ε1(0)从2.64增大为3.23.能量损失谱的计算表明,Al和N共掺后Zn1-xMgxO的等离子体共振频率发生蓝移,共振频率的振幅增大.     

Radiation-Temperature Reference Level in Waveguide Probe Measurement of Electron Plasma Temperature

It is shown that the waveguide probe determinations of electron temperature of shock-heated plasma reported in the literature contain two errors. The major one is due to the use of an incorrect reference level for the plasma radiation temperature; the other is due to the use of an incorrect equation for relating the raw data to the electron plasma temperature. The effects of these errors are examined.     

纤锌矿结构Zn1-xMgxO电子结构及吸收光谱的第一性原理研究

采用第一性原理计算方法,计算了纤锌矿结构Zn1-xMgxO(x=0,0.0625,0.125,0.25)的电子结构及吸收光谱. 计算结果表明,Mg的掺入使ZnO的电子结构发生了较大的改变,与Mg邻近的O原子得到电子的数目明显增大,进而O原子返回部分电子给邻近Zn原子. Zn-O间相互作用减弱,禁带宽度变大,这也从同一合金中Zn4s上移的程度得到证实. 其吸收光谱也随着Mg的掺入出现蓝移现象,其吸收边对应波长分别为379,366,357和333nm,与实验结果相一致.     

Electron Temperature Measurement in a Premixed Flat Flame Using the Double Probe Method

The electron temperatures T_e were measured using a double probe in a premixed methane flame produced by a calibration burner according to Hartung et al. The experiment was performed at atmospheric pressure. In contrast to other authors, we have managed to find typical nonlinearities corresponding to the retarding electron current region and to calculate electron temperatures using a suitable fit on the basis of the measured characteristics. A Pt‐Rh thermocouple was used to measure temperatures T_h corresponding to “heavy” species. Our results indicate that the flame plasma can be considered to be weakly non‐isothermic — T_e = (2400–4000) K, T_h = (1400–1600) K. On the basis of measurement of the saturated ion current, the number density of the charged particles was estimated at (0.3–3.8) · 10¹⁷ m^‐3. The trends in T_e and T_h in dependence on the positions of the probes and thermocouple in the flame differ substantially; this fact has not yet been explained (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Langmuir Probe Measurement of the Electron Temperature in the Plasma Plume Formed by Pulsed Laser Deposition of Bi-Sr-Ca-Cu-O

The electron temperature of the plasma formed during pulsed laser deposition of Bi-Sr-Ca-Cu-O target was measured using Langmuir probe. The main parameters of the experiment were as follows: The distance of the probe from the target was in the range of (4-6) mm, the basic working pressure was 2×10^–3 Pa and the planar pulse energy density of laser beam was approximately 8 J/cm². The obtained values of electron temperature were in the range of (1.0-2.5) eV. Presented results are discussed from the point of view of different theories of plasma splitting.     

电泳沉积法制备的Zn1-xCxO薄膜的结构及阻变性能

采用电泳沉积法在FTO导电玻璃基片上制备Zn_1-xCu_xO薄膜,并对其微观结构、光致发光谱、伏安特性、保持特性和转换电压分布进行探讨。PL谱表明,Cu掺杂在禁带中引入深受主能级,降低氧空位浓度,导致ZnO薄膜的紫外发光、蓝光发光和绿光发光峰强度降低。所得薄膜的晶粒细小、致密、均匀,具有稳定的双极性阻变特性,开关比R_off/R_on最高达到10⁵,其低阻态（LRS）和高阻态（HRS）的阻变机理分别符合欧姆定律和空间电荷限制传导理论。器件经100次循环测试后开关比无明显变化,呈现出较为良好的抗疲劳特性。Cu掺杂对LRS影响不大,但显著改善了HRS的分散性以及转换电压V_SET的分散性。当Cu掺杂量x=0.04时,器件表现出良好的综合性能：R_off≈10⁶ Ω,R_off/R_on≈10⁴,V_SET介于0.4~3.03 V之间。     

Al和N共掺p型Zn1-xMgxO电子结构的第一性原理计算

采用密度泛函理论下的第一性原理平面波超软赝势方法,对Zn1-xMgxO超晶胞和掺杂Al,N后的Zn1-xMgxO超晶胞分别进行了优化计算.结合广义梯度近似计算了Al和N共掺杂后Zn1-xMgxO的能带结构、电子态密度和Mulliken电荷布居分布.计算表明:掺入N原子的2p态电子为Zn1-xMgxO价带顶提供空穴载流子,使Zn1-xMgxO价带顶向高能方向移动;掺入Al原子的3p态电子则与N原子的2p态电子在费米能级附近发生轨道杂化,使费米能级处价带能级展宽,Al和N共掺杂可获得p型Zn1-xMgxO.     

用电子束热蒸发技术制备ZnO薄膜

本文报道了用电子束热蒸发技术制备ZnO薄膜,薄膜具有（002）取向,通过电子扫描显微镜确认晶粒大小在150nm左右,现有的薄膜在525nm处有强的光致发光。     

Surface Modification of Silver Iodide Films by Electron Irradiation

It has been found experimentally that electron irradiation of polycrystalline AgI films leads to the formation of a nanocrystalline silver particle monolayer. With an increase in the irradiation time, the nanoparticle size grows but the concentration of the particles first increases and then drops. Formation mechanisms of the nanoparticles and the dynamics of their growth have been considered. Ostwald’s ripening, fieldinduced migration, and nanoparticle charge variation during irradiation by low-energy electrons have been shown to be the main processes responsible for the above effects.     

火焰原子吸收光谱法测定盐酸金霉素中的锌、铁和镁

研究了火焰原子吸收光谱法测定盐酸金霉素中Zn、Fe、Mg的方法.方法的检出限Zn:0.006、Fe:0.03、Mg:0.003 mg/L,回收率98%-104%,RSD小于1.45%.结果表明,该方法准确、快速、结果令人满意.