氧分压对磁控溅射β-Ga2O3薄膜结构及光学特性的影响

通过磁控溅射沉积以及高温热退火处理,在5.08 cm(2 inch)c-plane蓝宝石异质衬底上制备出单晶β-Ga2O3薄膜,研究了溅射气氛中氧分压对β-Ga2O3薄膜的晶体结构以及光学特性的影响.通过调控氧分压,获得了具有{-2 01}晶面族X射线衍射峰的β-Ga2O3薄膜,其最大晶粒尺寸达到138 nm,在300～800 nm波段透射率大于80％,最大光学带隙达5.12 eV.最优的薄膜表面粗糙度达0.401 nm,800 nm波长处折射率为1.94.实验结果表明,降低氧分压有利于溅射粒子动能增大、数量增多,从而提升β-Ga2O3薄膜结晶质量、增加薄膜透射率和光学带隙;适当提高氧分压则有利于改善薄膜表面平整度,并提高致密度.     

Cu(In,Ga)Se2薄膜的制备及其表征

CuIn1-xGaxSe2(CIGS)为直接带隙半导体,其带隙宽度随In/Ga比而变化,且对可见光具有很高的吸收系数,是最有希望用于制作新一代高效、低成本薄膜太阳能电池的材料.采用直流溅射和后硒化工艺制备了系列CIGS薄膜,研究了溅射功率和衬底对CIGS薄膜的微结构和光学性质的影响.发现钼玻璃上溅射功率为50W,在55...     

纳米Al夹层Ga_2O_3深紫外透明导电膜的研究

用磁控溅射法在室温条件下制备了Al膜、Ga2O3膜及Ga2O3/Al/Ga2O3三层膜,对其光学和电学性能进行了表征。单层Al膜厚度大于7nm时,光学透射率在近紫外光区域大于可见光区域;Ga2O3膜在深紫外光区域(<300nm)透明,光学带隙4.96eV;Ga2O3/Al/Ga2O3三层膜透射率截止波长在245nm左右,随着顶层Ga2O3厚度增加,电导率减小,紫外光透射率峰位、吸收边、截止波长红移,透射率峰值先稍微增加,然后逐渐降低。顶层Ga2O3厚度为34nm时,Ga2O3/Al/Ga2O3三层膜在275nm处的透射率达70%,电导率为3346S.cm–1。     

高RF功率制备的ZnO:Li薄膜性能研究

实验采用射频(RF)磁控溅射法在高射频功率(550 W)下制备了Zn0.9Li0.1O薄膜,探讨了薄膜的光学性能,并与低溅射功率制备的薄膜性能进行了比较。结果表明,高功率下溅射的薄膜晶粒均匀细小,表面平整致密,在可见光波长范围内,透过率达80%。该薄膜的光学带隙约3.29 eV,明显低于低功率溅射的薄膜(3.44 eV)。其室温光致发光(PL)谱结果显示,最强峰是由Li杂质能级引起的399 nm峰,热处理后,370 nm的带间发光峰增强,而低功率制备的薄膜其PL谱与纯ZnO材料的特征谱相似。     

低真空下射频磁控溅射法制备ITO薄膜

在低真空(2.3×10-3 Pa)下采用射频磁控溅射法制备了ITO薄膜.溅射温度200 ℃,溅射气氛为氩气和氧气的混合气,溅射靶材为90 %氧化铟、10 %氧化锡的陶瓷靶.用场发射扫描电子显微镜和X衍射仪研究了薄膜的显微结构, 用X射线光电子能谱表征了薄膜的成分.ITO薄膜在可见光范围内有较高的透射率(80 %～95 %).在低工作气压(1 Pa)下,氧气流量比率[O2/(O2+Ar)]越小,薄膜的透射率越高、导电性越好.在高工作气压(2 Pa)下,制备得到低质量、低透射率的无定形薄膜.     

不同溅射功率制备的Zn0.97Co0.03O薄膜的结构和光学性质研究

采用磁控溅射法在不同射频功率下制备了Zn_(0. 97)Co_(0. 03)O薄膜。利用X射线衍射(XRD)、拉曼光谱(Raman)、紫外-可见光谱和室温光致发光谱对薄膜进行了表征。XRD和Raman结果表明,Zn_(0. 97)Co_(0. 03)O薄膜为六方纤锌矿结构,沿(002)晶面择优取向。随着溅射功率的增大,薄膜的(002)晶面择优取向增强,晶化程度提高,晶粒尺寸增大。不同溅射功率制备的Zn_(0. 97)Co_(0. 03)O薄膜均具有较高的可见光透过率。随溅射功率增加,光学带隙减小,光吸收边红移。光致发光谱表明不同溅射功率制备的Zn_(0. 97)Co_(0. 03)O薄膜均具有较强的带边紫外发光峰。随着溅射功率的增加,该发光峰的峰位发生红移,且峰强度增强。以上研究结果表明,溅射功率对Zn_(0. 97)Co_(0. 03)O薄膜的生长速率、结晶质量及光学性能有明显影响,但不会影响薄膜的成分。     

竹叶状GaN纳米带的制备

为了制备GAN纳米带,用射频磁控溅射法在Si(111)衬底上先溅射ZnO中间层,接着溅射Ga2O3,然后ZnO/Ga2O3膜在开管炉中1000℃下常压通氨气进行氨化。在氨气气氛中ZnO在高温下挥发,借助于ZnO挥发的帮助,Ga2O3与NH3反应自组装生成GaN纳米带。XRD分析结果表明GaN纳米带为六方纤锌矿结构,利用SEM观测GaN纳米带具有竹叶状形貌,PL谱测量发现了位于370nm处和460nm处的室温光致发光峰。     

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。     

（英）弛豫铁电0.74Pb(Mg1/3Nb2/3)O3-0.26PbTiO3薄膜的微结构和光学性能

采用磁控溅射法,选用LaNi O3作为缓冲层,在硅基片上制备出了0.74Pb(Mg1/3Nb2/3)O3-0.26PbTiO3弛豫铁电薄膜.研究了沉积温度对薄膜的微结构和光学性能的影响.其中,沉积温度为500oC时制备的薄膜,不仅具有纯的钙钛矿结构,高度(110)择优取向、致密、无裂纹的形貌、而且具有最大的剩余极化,大小为17.2μC/cm2.使用柯西模型进行拟合反射谱,分析得到薄膜的折射率和消光系数.在波长为633 nm时,500oC沉积的薄膜的折射率大小为2.41.另外,薄膜的光学带隙在2.97～3.22 eV范围内.并初步讨论了这些薄膜的光学性能的差异.     

磁控溅射中工艺参数对ZnO:Al薄膜性能的影响

利用射频磁控溅射法采用氧化锌铝(98%ZnO+2%Al2O3)为靶材在普通载玻片上制备了ZAO(ZnO∶Al)薄膜,研究了溅射功率及溅射气压对薄膜晶体结构、电学和光学性能的影响。利用X射线衍射仪、场扫描电镜对薄膜的结构及表面形貌进行了分析,利用分光光度计和电阻测试仪分别测试了薄膜的光电学性能。结果表明:溅射功率为120W、衬底温度为300℃、工作气压为0.5Pa时制得的薄膜具有良好的光电学性能(可见光平均透过率为88.21%、电阻率为8.28×10-4Ω.cm)。     

氮气流量对磁控溅射C掺杂TiO2薄膜光学性能的影响

采用磁控溅射法制备了C掺杂TiO₂薄膜,并研究了氮气引入溅射过程对薄膜光学性能的影响。利用X射线衍射仪、拉曼光谱仪、X射线光电子能谱仪、分光光度计和原子力显微镜分析了不同氮气流量下薄膜的微结构、元素价态、透光性能和表面形貌。结果表明,沉积的薄膜主要是非晶结构,拉曼光谱中存在少量锐钛矿相,且随着氮气流量增大,锐钛矿特征峰强度减弱,意味着晶粒出现细化。当氮气流量增大为4cm³/min时,C掺杂TiO₂薄膜内氮元素含量为3.54%,其光学带隙从3.29eV变化至3.55eV,可见光区的光学透过率明显提高。可见改变氮气流量可实现对C掺杂TiO₂薄膜光学带隙和光吸收率的有效调控。     

Characterization and ellipsometric investigation of high-quality ZnO and ZnO(Ga2O3) thin alloys by reactive electron-beam co-evaporation technique

High-quality ZnO(Ga₂O₃) thin films have been co-evaporated by reactive electron-beam evaporation in an oxygen environment. The effect of Ga₂O₃ on the structural and optical properties has been investigated. X-ray diffraction (XRD) measurements have shown that the ZnO(Ga₂O₃) alloys are c-axis-oriented. The alloy containing 28% of Ga₂O₃ showed the best crystallinity. Photoluminescence on ZnO(28%Ga₂O₃) reveals an enhancement of the ultraviolet near band edge emission at 380 nm while the intensity of the deep-level emissions weakens. A reduction of the oxygen vacancies as well as the reduction of the zinc interstitials with gallium may explain this effect. Thus, the possibility of transitions of electron in the conduction band to a deep acceptor level due to zinc interstitials may decrease. Finally, ellipsometric measurements show that the optimum weight concentration of gallium oxide in the alloys is 28%, thus correlating with the XRD and photoluminescence measurements.     

掺氮氧化铪的光学特性研究

掺氮氧化铪是半导体工业非常重要的材料。在本论文中,我们利用Hf[N(C₂H₅)(CH₃)]₄ 和 H₂O₂作为原子层淀积的前驱体,制备了二氧化铪材料。然后,我们使用快速热退火的办法,在不同温度下,对二氧化铪进行了氮掺杂工艺。我们对掺氮二氧化铪的组分,跟硅界面的稳定性以及薄膜材料的光学特性随退火温度的变化进行了细致的研究。研究发现,随着退火温度的提高,二氧化铪薄膜材料的氮组分从1.41% 上升至 7.45%,相应的,薄膜材料的禁带宽度从5.82 eV 降低为 4.94 eV。     

High-k HfO2-Ta2O5 mixed layers: Electrical characteristics and mechanisms of conductivity

Electrical properties of mixed HfO₂-Ta₂O₅ films (10;15 nm) deposited by rf sputtering on Si have been studied from the view point of their applications as high-k layers, by standard capacitance-voltage and temperature dependent current-voltage characteristics. The effect of HfO₂ addition to the Ta₂O₅ is thickness dependent and the thicker layers exhibit advantages over the pure Ta₂O₅ (higher dielectric constant, enhanced charge storage density and improved interface quality). The process of HfO₂ and Ta₂O₅ mixing introduces negative oxide charge, tends to creates shallow bulk traps and modifies the dominant conduction mechanisms in the stack capacitors as compared to the Ta₂O₅-based one (a contribution of tunneling processes through traps located below the conduction band of mixed layers to the leakage current in the HfO₂-Ta₂O₅ stacks is observed). The traps involved in both Poole-Frenkel and tunneling processes are identified.     

Improvement on low-temperature deposited HfO2 film and interfacial layer by high-pressure oxygen treatment

In this study, high-pressure oxygen (O₂ and O₂ + UV light) technologies were employed to effectively improve the properties of low-temperature-deposited metal oxide dielectric films and interfacial layer. In this work, 13 nm HfO₂ thin films were deposited by sputtering method at room temperature. Then, the oxygen treatments with a high-pressure of 1500 psi at 150 °C were performed to replace the conventional high temperature annealing. According to the XPS analyses, integration area of the absorption peaks of O-Hf and O-Hf-Si bonding energies apparently raise and the quantity of oxygen in deposited thin films also increases from XPS measurement. In addition, the leakage current density of standard HfO₂ film after O₂ and O₂ + UV light treatments can be improved from 3.12 × 10⁻⁶ A/cm² to 6.27 × 10⁻⁷ and 1.3 × 10⁻⁸ A/cm² at |Vg| = 3 V. The proposed low-temperature and high pressure O₂ or O₂ + UV light treatment for improving high-k dielectric films is applicable for the future flexible electronics.     

NH3-Ar气氛下制备的Zn3N2薄膜的结构和光学性能

在NH3-Ar气氛下,用RF磁控溅射金属Zn靶在玻璃衬底上室温制备了Zn3N2薄膜,研究了NH3分压对Zn3N2薄膜的结构和光学特性的影响。XRD分析表明Zn3N2薄膜出现多晶结构,具有(321)择优取向。当NH3分压从5%变化到25%时,Zn3N2薄膜的间接光学带隙从2.33eV升高到2.70eV。室温下Zn3N2薄膜在437nm和459nm波长出现了发光峰,并对发光机理进行了分析。     

溅射压力对制备a-GaAs1-xNx 薄膜光学常数的影响

采用反应磁控溅射法在室温条件下制备了a-GaAs_1-xN_x 薄膜。实验测定了薄膜厚度、氮含量、载流子浓度和光学透过率及并研究了其随溅射压的变化。系统研究了溅射压对所制备薄膜的光学带隙、折射率和色散参数的影响。所制备的薄膜为直接带隙材料,利用Cauchy和Wemple模型能够很好地拟合所制备薄膜的折射率色散曲线。     

新型相变材料Al1.3Sb3Te使用CF4/Ar等离子体干法刻蚀

对使用CF4/Ar 混合气体刻蚀Al1.3Sb3Te的特性进行了研究。实验控制的参数是：气体流入刻蚀腔的速率,CF4/Ar 比例,O2的加入量,腔内压强以及加在底电极上的入射射频功率。总的气体流量是50sccm ,研究刻蚀速率与CF4/Ar的比例,O2加入量,腔内压强和入射射频功率的关系。最后刻蚀参数被优化。 使用优化的刻蚀参数CF4的浓度4%,功率300W,压强800mTorr,刻蚀速率达到70.8nm/min,刻蚀表面平整     

Influence of N2 and O2 annealing treatment on the optical bandgap of polycrystalline Ga2O3:Cu films

Cu-doped Ga₂O₃ thin films were deposited by electron beam evaporation with subsequent annealing at 1000 °C in N₂ and O₂ for 1 h. The influence of the annealing atmosphere on the crystal structure, surface morphology and optical properties of Ga₂O₃:Cu films was investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), and transmittance and photoluminescence (PL) spectroscopy. The optical bandgap deduced from the absorption spectrum was greater for the O₂ annealed than for N₂ annealed samples. In both cases the bandgap was wider than for bulk β-Ga₂O₃. The grain size and surface roughness were sensitive to the annealing atmosphere. Results confirmed that the annealed samples were polycrystalline β-Ga₂O₃ with some amorphous phase. We hypothesize that annealing in oxygen led to recrystallization of the Ga₂O₃:Cu film. Annealing treatment improved the crystal quality of Ga₂O₃:Cu films and the PL intensity of the samples increased.     

用溶胶-凝胶法制备的Cu2Bi2Cr2O8薄膜 及其光学和铁磁性能研究

以硝酸铜Cu(NO₃)₂·3H₂O、硝酸铬Cr(NO₃)₃·9H₂O、硝酸铋Bi(NO₃)₃·3H₂O和乙二醇为原料,利用溶胶-凝胶工艺在石英衬底上制备了纳米Cu₂Bi₂Cr₂O₈薄膜。通过X射线衍射(X-Ray Diffraction, XRD)和拉曼测试对样品进行了表征。结果表明,Cu₂Bi₂Cr₂O₈薄膜具有良好的光学特性,其禁带宽度为1.49 eV;在磁性测试方面,Cu₂Bi₂Cr₂O₈薄膜呈现出了良好的铁磁性。