H2 气对脉冲磁控溅射铝掺杂氧化锌薄膜性能的影响

实验采用脉冲磁控溅射法制备铝掺杂氧化锌(AZO)薄膜.为了进一步提高AZO薄膜的光电性能,在溅射过程中加入一定流量的氢气,以高纯ZnO ∶Al₂O₃陶瓷靶为溅射靶材,制备AZO/H透明导电薄膜.通过测试薄膜的结构特性、表面形貌及其光电性能,详细地研究了氢气流量对AZO薄膜性能的影响.溅射过程中引入氢气,可以促进薄膜的晶化,提高薄膜的迁移率和透过率(400—1100 nm).采用纯氩气溅射制备AZO薄膜的电阻率为5.664×10^-4 Ω·cm 关键词： 氧化锌 氢气流量 磁控溅射 太阳电池     

ZnO:Fe薄膜制备、光学与电学性质研究

用双靶磁控溅射设备制备了ZnO:Fe薄膜。分析了铁靶溅射功率对薄膜的光学及电学性质的影响。X射线衍射(XRD)和原子力显微镜(AFM)图像表明:ZnO:Fe薄膜为六角纤锌矿结构,且具有非常好的沿垂直于衬底的c轴择优取向。当铁靶功率小于250W时,沉积速率随铁靶功率的增加而增加。随着铁靶功率的增加,透射光谱的吸收边有微弱蓝移,透过率在可见光区超过75%。掺铁后薄膜的电阻率只有10-2Ω.cm,远小于纯氧化锌的电阻率。通过实验得到ZnO:Fe薄膜的最佳制备条件。     

氢气引入对宽光谱Mg和Ga共掺杂ZnO透明导电薄膜的特性影响

为适应宽光谱高效率硅基薄膜太阳电池的应用需求,本文尝试采用直流磁控溅射技术在553 K衬底温度下生长氢化Mg和Ga共掺杂ZnO(HMGZO)透明导电氧化物(TCO)薄膜.通过对薄膜微观结构、表面形貌、电学以及光学性能的测试和分析,详细地研究了氢气(H2)流量(0—16.0 sccm)对HMGZO薄膜结晶特性及光电性能的影响.实验结果表明:生长获得的HMGZO薄膜均为六角纤锌矿结构的多晶薄膜,择优取向为(002)晶面生长方向.薄膜的生长速率随着氢气流量的增加呈现逐渐减小趋势,主要归因于溅射产额的减小.适当的氢气引入会引起晶粒尺寸的增加.随着氢气流量由0增加至4.0 sccm,ZnO薄膜电阻率从177?·cm急剧减小至7.2×10-3?·cm,主要是由于H施主的引入显著地增加了载流子浓度;然而进一步增加氢气流量(4.0—16.0 sccm)造成电阻率的轻微增加,主要归因于载流子浓度的减小以及过多氢杂质引入造成杂质散射的增加.所有生长获得的HMGZO薄膜平均光学透过率在波长λ～320—1100 nm范围内可达87%以上.由于Mg的作用及Burstein-Moss效应的影响造成了带隙展宽,带隙变化范围～3.49—3.70 eV,其中最大光学带隙Eg可达～3.70 eV.     

氩气压强对射频磁控溅射ZnO：Al薄膜结构和性能的影响

以ZnO:Al2O3为靶材在石英玻璃衬底上射频磁控溅射制备多晶ZnO:Al(AZO)薄膜,通过XRD、AFM以及Hall效应、透射光谱等测试研究了RF溅射压强对薄膜结构、电学与光学性能的影响.分析表明:所制备的薄膜具有c轴择优取向,当压强为1.2Pa时薄膜的电阻率降至最低(2.7×10-3Ω·cm).薄膜在可见光区平均透射率高于90%,光学带隙均大于本征ZnO的禁带宽度.     

沉积参数对SiNx薄膜结构及阻透性能的影响

利用直流脉冲磁控溅射法在室温下制备无氢SiNx,薄膜.通过傅里叶变换红外光谱、台阶仪、紫外一可见分光光度计、接触角测量仪、透湿测试仪等表征技术,分析了N2流量、Si靶溅射功率等实验参数对SiNx薄膜成分、结构、及阻透性能、透光性能、接触角等性能的影响.研究结果表明,Si靶溅射功率固定时,在低N2流量条件下,或N2流量固定时,在高Si靶溅射功率条件下,制备的SiN,薄膜中Si-N键含量高,结构致密,薄膜对H2O的阻透性能优良,随着N2流量的增加或者Si靶溅射功率的降低,SiNx,薄膜成分、结构发生变化,红外光谱发生偏移,其对H2O的阻透性能下降.在N2流量为6 sccm,Si靶溅射功率为300 W时制备的SiN,薄膜在可见光波段透过率超过97.5%,对H2O的接触角为30,同时其对H2O的渗透系数最低,为0.764,综合性能满足柔性有机电致发光器件封装用阻透膜的要求,因此SiNx薄膜有望成为新一代柔性有机电致发光器件封装用阻透材料.     

B掺杂ZnO透明导电薄膜的实验及理论研究

采用脉冲直流磁控溅射技术与基于密度泛函理论的平面波赝势方法对B掺杂ZnO （BZO）薄膜进行了研究. 以B₂O₃：ZnO陶瓷靶为溅射靶材,制备了低电阻率、可见和近红外光区高透过率的BZO薄膜. 系统地研究了衬底温度对BZO薄膜的结构、光电特性的影响. 结果表明：适当的增加衬底温度可以促进BZO薄膜结晶质量改善,晶粒尺寸增加,迁移率增大,电阻率降低. 在200 ℃时制备了电阻率为7.03×10^-4 Ω·cm,400–1100 nm平均透过率为89%的BZO薄膜. 理论模拟结果表明：在BZO薄膜中,以替位方式掺入的B （B_Zn）的形成能最低,B主要以替位形式掺入ZnO,其次分别为八面体间隙（B_IO）和四面体间隙（B_IT）的掺杂方式. B 掺入后,费米能级穿过导带,材料表现出n型半导体特性,光学带隙展宽,导电电子主要来源于B 2p,O 2p及Zn 4s电子轨道. 关键词： BZO薄膜 第一性原理计算 磁控溅射 太阳电池     

RF磁控溅射条件对ZnO薄膜结构的影响

采用RF磁控溅射法在Si（001）衬底上制备ZnO薄膜。研究发现了工作中溅射频率、氧气和氩气流量比对样品结构的影响。样品的XRD图谱显示了强的（002）ZnO衍射峰，表明ZnO薄膜为c轴高取向生长。比较不同条件下制备的ZnO薄膜，研究发现当氧气和氩气的流量比相同时，随着溅射功率的增加，样品的（002）衍射峰增强，半高全宽变小。而当溅射功率相同时，随着氧气和氩气的流量比增加，样品的（002）衍射峰也增强，半高全宽同样变小。此外，本文还分析了溅射工艺和薄膜晶体质量之间关系，发现在相同的功率条件下，溅射率低时晶粒尺寸更大且薄膜的结晶性更好。     

溅射气氛对N掺杂ZnO薄膜性能的影响

利用磁控溅射系统,N₂和Ar作为溅射气体,生长N掺杂ZnO薄膜。溅射气氛中氮气流量分别为0,8,20,32 mL/min,通过改变氮气的流量,研究薄膜性能的变化。结果发现,随着溅射气氛中氮气流量的增加,薄膜的电阻率增加,薄膜中N_O与(N₂)_O的掺杂浓度同时在变大。当氮气流量为8 mL/min时,N的有效掺杂效率最高。另外,随着溅射气氛中氮气流量的增加,薄膜的厚度在减小。     

额定压强下O_2/Ar比对ZnO:Al薄膜导电性能的影响

采用射频磁控溅射法在石英玻璃基片上制备出ZnO:Al薄膜,并对薄膜在不同O2/Ar比状态下的沉积厚度、结晶性能和导电性能之间的关系进行了探讨。测试结果表明:在0.2Pa的额定压强下,Ar流量越大,薄膜的厚度越大,XRD峰越强,薄膜的电阻率(ρ)值越低。在纯氩气状态下溅射时,制得的薄膜具有最大的厚度值,约为2.06μm,并具有最强的XRD峰,ρ同时也达到最小值,阻值为2.66×10-4Ω.cm。研究表明:结晶性能的提高对薄膜ρ的降低起到了关键作用,而厚度的增加也会使电阻率下降。     

H掺杂对ZnCoO稀磁半导体薄膜结构及磁性能的影响

利用磁控溅射法,采用亚分子分层掺杂技术交替溅射Co靶和ZnO靶,在Si衬底上制备了不同氢氩流量比的H:ZCO薄膜样品,研究了氢氩流量比对薄膜结构特性和磁学性能的影响。所制备的薄膜样品具有c轴择优取向。由于H对表面和界面处悬挂键的钝化作用,随H₂流量比的增加,薄膜的择优取向变差。磁性测量结果显示,薄膜样品的铁磁性随着氢氩流量比的增大而增强。XPS结果表明,随着H含量的增大,金属态Co团簇的相对含量逐渐增加,而氧化态Co离子的相对含量逐渐减小。H:ZCO样品中的铁磁性可能来源于Co金属团簇,H的掺入促使ZnO中的Co离子还原成Co金属团簇,从而增强了薄膜样品的室温铁磁性。     

The properties of transparent conducting molybdenum-doped ZnO films grown by radio frequency magnetron sputtering

Transparent conducting molybdenum-doped zinc oxide films are prepared by radio frequency(RF) magnetron sputtering at ambient temperature.The MoO3 content in the target varies from 0 to 5 wt%,and each film is polycrystalline with a hexagonal structure and a preferred orientation along the c axis.The resistivity first decreases and then increases with the increase in MoO3 content.The lowest resistivity achieved is 9.2 × 10-4.cm,with a high Hall mobility of 30 cm2.V-1.s-1 and a carrier concentration of 2.3×1020 cm-3 at an MoO3 content of 2 wt%.The average transmittance in the visible range is reduced from 91% to 80% with the increase in the MoO3 content in the target.     

Excitation of the 3p3Πu level of H2 by electron impact; pressure effects

The excitation cross-section of the 3p³Π_u level of H₂ has been measured for electrons from energy threshold to 100 eV. We compare the intensities of the emitted lines to the Balmer lines whose excitation cross-sections from H₂ are known. The effects of dissociation, cascade, polarisation and pressure are discussed. The maximum excitation cross-section is found to be 3·30 × 10^-18 cm² ± 50% at 22·5 eV.     

Cross sections for slow ion production and charge transfer in H+3(D+3)−H2(D2) collisions

Slow ion production cross sections for collisions of H⁺₃ and D⁺₃ ions with H₂ and D₂ have been measured at collision energies between 100 eV and 500 eV. The values vary from 2 × 10^-17 cm² to 6 × 10^-17 cm². The smaller cross sections for D₃ projectiles may be explained as an internal energy effect.     

Kinetic mechanisms of the uptake of atmospheric gases on the surface of sea salts. ClNO3 uptake on MgCl2 · 6H2O/NaCl

The uptake coefficients γ of chlorine nitrate on MgCl₂ · 6H₂O crystallites and a MgCl₂ · 6H₂O-NaCl mixture deposited from an aqueous solution are measured using a flow reactor with a movable salt-substrate-coated insert equipped in combination with a mass spectrometer at 295–428 K, [ClNO₃] = (0.2?12) × 10¹² cm^?3, and [H₂O] = 1.0 × 10¹² ? 4.3 × 10¹⁵ cm^?3. Immediately after the exposure of the salt substrate to a ClNO₃ flow, γ(t) decreases exponentially with time, γ(t) = γ₀ × exp(?t/τ) + γ _s , to a steady-state level, γ _s , which depends on the temperature and the ClNO₃ and H₂O concentrations. The main gas-phase product is Cl₂, HOCl appears only when water vapor is admitted into the reactor. The coefficient of steady-state uptake on wetted MgCl₂ · 6H₂O at 295 K can be described by the approximation γ = a + b [H₂O] with a = 3.5 × 10^?3 cm³ and b = 3.2 × 10^?18 cm³. The mechanism of the uptake of ClNO₃ on MgCl₂ · 6H₂O is discussed. The experimental data are treated within the framework of a steady-state uptake model to estimate the heat of adsorption of ClNO₃ on MgCl₂ · 6H₂O (Q _ad = 62 kJ/mol) and the activation energy of the bimolecular heterogeneous reaction ClNO₃ + Z _s = 2Cl₂ + Mg(NO₃)₂ · 6H₂O (E _a = 21.8 kJ/mol; Z _s denotes a ClNO₃-MgCl₂ · 6H₂O surface complex). When the MgCl₂ · 6H₂O: NaCl is varied from 0 to ～3 wt %, the steady-state uptake coefficient changes from the value corresponding to uptake on pure NaCl to that characteristic of uptake on pure MgCl₂ · 6H₂O.     

Ionic transport in the lithium nitride bromides,Li6NBr3 and Li1 3N4Br

The ionic and electronic conductivities of the lithium nitride bromides Li₆NBr₃ and Li_{1 3}N₄Br have been studied in the temperature range from 50 to 220°C and 120 to 450°C, respectively. Both compounds are practically pure lithium ion conductors with negligible electronic contribution. Li₆NBr₃ has an ionic conductivity Ω of 2 × 10^-6Ω^-1cm^-1 at 100°C and an activation enthalpy for σT of 0.46 eV. Li_{1 3}N₄Br shows a phase transition at about 230°C. The activation enthalpy for σT is 0.73 eV below and 0.47 eV above this temperature. The conductivities at 150 and 300°C were found to be 3.5 × 10^-6 Ω^-1cm^-1 and 1.4 × 10^-3Ω^-1cm^-1, respectively. The crystal structure is hexagonal at room temperature with $\text{a = 7.415 (1)}\text{A}\text{?}$ and $\text{c = 3.865 (1)}\text{A}\text{?}$.     

Conductivity of β″ and ion rich β alumina.I.H.+(H2O)n compounds

The conductivity and thermal stability of H⁺(H₂O)_n β″ and ion rich β alumina single crystals have been measured by the complex impedance method in the 25–700°C temperature range. Two mechanisms of conductivity were assumed: proton transfer at lower temperatures and H₃O⁺ diffusion in the high-temperature range. Both structures have similar properties, but ion rich β alumina possesses the best stability and the lowest activation energy (β: 0.15 eV, β″: 0.20 eV below 400 and 300°C respectively). The room-temperature conductivity is ≈5×10^?6 Ω^?1 cm^?1. The conducting properties and mechanisms are discussed and compared to other protonic or ionic conductors.     

Radiation defects in Si of high purity

Abstract

Radiation defects created by γ-irradiation of Co⁶⁰ and fast neutrons in high purity p-Si (p = 5×10³ to 4 × 10⁴ Ω.cm) and n-Si (p = 4 × 10² to 5 × 10³ Ω.cm) are investigated by measurements of Hall effect, resistivity and minority carrier lifetime. The oxygen concentration in the crystals is in the range of 5 × 10¹⁴ to 5 × 10¹⁵ cm^?3.

It is shown that stable γ-defects at 300 °K are divacancies and complexes of vacancies with donor or acceptor impurities. Divacancies introduced by γ-irradiation are the secondary defects. They become predominant after ‘exhaustion’ of the dopant. When divacancies become the predominant defects the Fermi level occupies its boundary position E_v +0.39 eV in the gap. At low doses (Φ<10¹⁶ photons/cm²) vacancy-impurity complexes and at heavy doses (Φ>10¹⁷ photons/cm²) divacancies play the main role in the recombination process.

In neutron irradiation disordered regions are introduced and the level at E_v +0.35 eV is observed. The Fermi level in both n- and p-Si shifts to the middle of the gap. At the annealing of disordered regions in the interval 200 to 250 °C the level at E_v +0.27 eV appears and Fermi level occupies its boundary position at E_v +0.39 eV. This indicates that divacancies become the predominant defects which can be formed as secondary defects at the destruction of the disordered regions.     

一种测定某些离子导体的导电基本参数的新方法

利用低频交变电场在某些离子导体中能引起偏振态改变的光衍射特性,发展了一种测量这些离子导体的导电基本参数的新方法,并且用它测定了α-LiIO₃单晶的基本离子导电参数,测得其载流子的迁移率激活能E_μ=0.36eV;夫仑克耳缺陷的形成能为E_M=0.59eV;300K时正、负载流子的数密度均为1.6×10¹⁷cm^-3,相对浓度均为1.07×10^-5;当所加电场反平行于晶体的自发极化强 关键词：     

The ground-state rotational constants of silane

From thirty-nine combination difference equations we have determined three significant ground-vibronic state constants of silane: β ⁰/hc=2·85941 cm^-1, γ ⁰/hc=-3·82×10^-5 cm^-1 and ε ⁰/hc=-7·97×10^-7 cm^-1 or in Hecht's notation B ₀=2·85941 cm^-1, D _s=3·82×10^-5 cm^-1 and D _t=2·436×10^-6 cm^-1.     

Fabrication and characterization of 4H—SiC bipolar junction transistor with double base epilayer

In this paper we report on a novel structure of a 4H-SiC bipolar junction transistor with a double base epilayer that is continuously grown.The measured dc common-emitter current gain is 16.8 at IC = 28.6 mA(J C = 183.4 A/cm2),and it increases with the collector current density increasing.The specific on-state resistance(Rsp-on) is32.3mΩ·cm 2 and the open-base breakdown voltage reaches 410 V.The emitter N-type specific contact resistance and N + emitter layer sheet resistance are 1.7×10-3 Ω·cm2 and 150 /,respectively.