溅射气压对氧化镓薄膜光学特性的影响

采用射频磁控溅射法在石英衬底上制备了氧化镓(Ga2O3)薄膜.利用X射线衍射仪和紫外-可见-红外分光光度计分别对Ga2O3薄膜的晶体结构和光学带隙进行了表征,并在室温下测量了 Ga2O3薄膜的光致发光(PL)谱.结果表明:制备的Ga2O3薄膜呈非晶态.吸收边随着溅射气压的增加先蓝移后红移,光学带隙值范围为5.06～5.37 eV,溅射气压为1 Pa时,制备的Ga2O3薄膜具有最大的光学带隙.在325 nm激光激发下,400 nm附近和525 nm附近处出现与缺陷能级相关的发光峰.     

溅射参数对Ge_2Sb_2Te_5薄膜光学常数的影响

研究了溅射参数对 Ge2 Sb2 Te5 薄膜的光学常数随波长变化关系的影响 ,结果表明 :(1)当溅射功率一定时 ,随溅射氩气气压的增加 Ge2 Sb2 Te5 薄膜的折射率先增大后减小 ,而消光系数先减小后增大 .(2 )当溅射氩气气压一定时 ,对于非晶态薄膜样品 ,在 5 0 0 nm波长以下 ,折射率随溅射功率的增加先增加后减小 ,消光系数则逐渐减小 ;在 5 0 0 nm以上 ,折射率随溅射功率的增加逐渐减少 ,消光系数先减小后增加 .对于晶态薄膜样品 ,在整个波长范围折射率随溅射功率的增加先减小后增加 ,消光系数则逐渐减少 .(3)薄膜样品的光学常数都随波长的变化而变化 ,在长波     

溅射参数对Ge2Sb2Te5薄膜光学常数的影响

研究了溅射参数对Ge2Sb2Te5薄膜的光学常数随波长变化关系的影响,结果表明：(1)当溅射功率一定时,随溅射氩气气压的增加Ge2Sb2Te5薄膜的折射率先增大后减小,而消光系数先减小后增大.(2)当溅射氩气气压一定时,对于非晶态薄膜样品,在500nm波长以下,折射率随溅射功率的增加先增加后减小,消光系数则逐渐减小;在500nm以上,折射率随溅射功率的增加逐渐减少,消光系数先减小后增加.对于晶态薄膜样品,在整个波长范围折射率随溅射功率的增加先减小后增加,消光系数则逐渐减少.(3)薄膜样品的光学常数都随波长的变化而变化,在长波长范围变化较大,短波长范围变化较小.探讨了影响Ge2Sb2Te5薄膜光学常数的机理.     

衬底温度对氧化钛薄膜的光学常数影响

采用沈阳CK-3高真空磁控溅射薄膜沉积设备在K9玻璃衬底上分别制备了衬底温度为150℃、200℃和250℃的氧化钛薄膜。XRD分析显示这三种温度制备的薄膜由于制备温度不高均没有明显衍射峰,为非晶薄膜。薄膜的光学常数由德国SENTECH SE 850型光谱型椭偏仪对薄膜测试得到,测试波长为300 nm～800 nm,采用Cauchy模型对测试结果进行拟合。结果发现随着制备衬底温度的增大,薄膜的折射率n和消光系数k都随着增大。在衬底温度从150℃增大到250℃时,薄膜的光学带隙从3.46 eV减小到3.02 eV。     

溅射参数为Ge2Sb2Te5薄膜光学常数的影响

研究了溅射参数对Ge2Sb2Te5薄膜的光学常数随波长变化关系的影响。结果表明：（1）当浅射功率一定时,随溅射氩气气压的增加Ge2Sb2Te5薄膜的折射率先增大后减小,而消光系数先减小后增大。（2）当溅射氩气压一定时,对于非晶态薄膜样品,在500nm波长以下,折射率随溅射功率的增加先增加后减小,消光系数则逐渐减小;在500nm以上,折射率随溅射功率的增加逐渐减少,消光系数先减小后增加。 对于晶态薄膜样品,在整个波长范围折射率随溅射功率的增加先减小后增加,消光系数则逐渐减少。（3）薄膜样品的光学常数都随波长的变化而变化,在长波长范围变化较大,短波长范围变化较小,探讨了影响Ge2Sb2Te5薄膜光学常数的机理。     

掺铝对ZnO薄膜光学常数的影响

采用溶胶-凝胶法在(0001)蓝宝石衬底上制备了ZnO:Al薄膜,利用Kramers-Kronig色散关系对ZnO∶Al薄膜在300～600 nm波长区域的光学常数进行计算,研究了掺杂浓度对薄膜光学常数的影响.计算结果显示,在可见光区,薄膜的光学常数受铝掺杂浓度的影响很小,折射率、消光系数、复介电常数实部和虚部的数值基本恒定,分别约为1.6,0.08,0.27和2.5.在紫外区,薄膜光学常数受掺杂浓度的影响明显,随掺杂浓度提高,光学常数数值均减小,并且都在激子吸收峰(370 nm)处出现一极大值.     

溅射法制备a-GaN薄膜的光学性质

利用直流磁控溅射方法制备了非晶氮化镓（a-GaN）薄膜.X射线衍射分析以及傅里叶变换红外吸收谱表明薄膜是非晶结构.通过紫外-可见光谱测量得到，样品随着衬底温度的升高而变厚，光学带隙随着衬底温度的升高而变小，Ar对薄膜的光学带隙和表面粗糙程度有很大的影响.     

溅射法制备a-GaN薄膜的光学性质

利用直流磁控溅射方法制备了非晶氮化镓(a-GaN)薄膜.X射线衍射分析以及傅里叶变换红外吸收谱表明薄膜是非晶结构.通过紫外-可见光谱测量得到,样品随着衬底温度的升高而变厚,光学带隙随着衬底温度的升高而变小,Ar对薄膜的光学带隙和表面粗糙程度有很大的影响.     

溅射法制备a-GaN薄膜的光学性质

利用直流磁控溅射方法制备了非晶氮化镓(a-GaN)薄膜.X射线衍射分析以及傅里叶变换红外吸收谱表明薄膜是非晶结构.通过紫外-可见光谱测量得到,样品随着衬底温度的升高而变厚,光学带隙随着衬底温度的升高而变小,Ar对薄膜的光学带隙和表面粗糙程度有很大的影响.     

Influence of sputtering pressure on optical constants of a-GaAs1-xNx thin films*

Amorphous GaAs_1-xN_x(a-GaAs_1-xN_x) thin films have been deposited at room temperature by a reactive magnetron sputtering technique on glass substrates with different sputtering pressures.The thickness,nitrogen content,carrier concentration and transmittance of the as-deposited films were determined experimentally.The influence of sputtering pressure on the optical band gap,refractive index and dispersion parameters（E_o,E_d） has been investigated.An analysis of the absorption coefficient revealed a direct optical transition characterizing the asdeposited films.The refractive index dispersions of the as-deposited a-GaAs_1-xN_x films fitted well to the Cauchy dispersion relation and the Wemple model.     

利用拉曼谱鉴别锗硅合金微结构变化

随着硅浓度的增大,计算的拉曼谱结果表明,Ge-Si模式和Si-Si模式向高波数移动,而Ge-Ge模式向低波数移动,这种拉曼谱的变化强烈的依赖于合金微结构的变化。它的模式频率的线性变化依赖于Ge/Si的力学常熟的变化。这种现象可以用来鉴别合金中Si含量的浓度。可以通过拉曼散射表征这种复杂的微结构变化。     

Hybrid functional calculations on the band gap bowing parameters of InxGa1-xN

The electronic band structures and band gap bowing parameters of In_xGa_1-xN are studied by the firstprinciples method based on the density functional theory. Calculations by employing both the Heyd-ScuseriaErnzerh of hybrid functional（HSE06） and the Perdew-Burke-Ernzerhof（PBE） one are performed. We found that the theoretical band gap bowing parameter is dependent significantly on the calculation method, especially on the exchange-correlation functional employed in the DFT calculations. The band gap of In_xGa_1-xN alloy decreases considerably when the In constituent x increases. It is the interactions of s–s and p–p orbitals between anions and cations that play significant roles in formatting the band gaps bowing. In general, the HSE06 hybrid functional could provide a good alternative to the PBE functional in calculating the band gap bowing parameters.     

Sn掺杂对(In0.95-xSnxFe0.05)2O3薄膜的结构、电学及磁特性的影响

我们利用脉冲激光沉积的方法制备了一系列(In0.95-xSnxFe0.05)2O3 (x=0~0.09)薄膜,并在其中发现了室温铁磁性。X射线衍射结果表明锡与铁离子已掺入氧化铟晶格。随着锡的掺入,样品内的载流子浓度得到了很大的提高,但相应的铁磁性却几乎没有变化。我们认为氧空位相关的束缚磁极化子模型能够跟好的解释我们的铁掺杂氧化铟薄膜中的铁磁耦合的机制,而载流子传导的RKKY相互作用则不适用于这一系统。     

Large signal and noise properties of heterojunction AlxGa1-xAs/GaAs DDRIMPATTs

Simulation studies are carried out on the large signal and noise properties of heterojunction (HT) Al_xGa_1-xAs/GaAs double drift region (DDR) IMPATT devices at V-band (60 GHz). The dependence of Al mole fraction on the aforementioned properties of the device has been investigated. A full simulation software package has been indigenously developed for this purpose. The large signal simulation is based on a non-sinusoidal voltage excitation model. Three mole fractions of Al and two complementary HT DDR structures for each mole fraction i.e., six DDR structures are considered in this study. The purpose is to discover the most suitable structure and corresponding mole fraction at which high power, high efficiency and low noise are obtained from the device. The noise spectral density and noise measure of all six HT DDR structures are obtained from a noise model and simulation method. Similar studies are carried out on homojunction (HM) DDR GaAs IMPATTs at 60 GHz to compare their RF properties with those of HT DDR devices. The results show that the HT DDR device based on N-Al_xGa_1-xAs/p-GaAs with 30% mole fraction of Al is the best one so far as large signal power output, DC to RF conversion efficiency and noise level are concerned.     

InP-based InxGa1-xAs metamorphic buffers with different mismatch grading rates

Linearly graded In_xGa_1-xAs metamorphic buffers with different mismatch grading rates were grown on InP substrate by gas source molecular beam epitaxy.Room temperature photoluminescence spectra show that the sample with lower mismatch grading rate in the buffer has stronger photoluminescence signal,indicating the improved optical property.Atomic force microscope images show that the lower mismatch grading rate in the buffer leads to a slightly rougher surface.The relaxation procedure with two steps in the buffer layers has been observed by X-ray diffraction reciprocal space mapping.The measurements of X-ray diffraction also reveal that the lower mismatch grading rate in the buffer is beneficial for the lattice relaxation and release of residual strain.To further increase the relaxation degree,a lower mismatch grading rate and composition "overshoot" are suggested.     

采用杂化函数方法研究BxGa1-xN合金中的能带弯曲和交叉

采用Perdewe-Burkee–Ernzerhof的广义梯度近似（GGA-PBE）及Heyd-Scuseria-Ernzerhof屏蔽杂化函数方法(HSE06)对比研究了闪锌矿结构BxGa1-xN合金的电子结构性质。HSE06计算方法给出更接近实验结果的基态性质。采用两种计算方法得到的直接带隙的能带弯曲系数b? 都很大且依赖于成分；由两种方法得到的由直接带隙向间接带隙转变的合金成分非常相近。当向GaN中掺入小于55.7%的硼时，可以得到带隙值比GaN大的直接带隙BxGa1-xN 合金。     

微波法制备高活性H1-xSr2Nb3-xMoxO10 (x = 0, 0.05, 0.1, 0.15 and 0.2) 光催化剂

通过微波辅助法制备出高活性H1-xSr2Nb3-xMoxO10光催化材料,制备过程和时间均被大大缩短。采用X射线粉末衍射（XRD）、扫描电镜（SEM）、紫外-可见吸收吸收光谱（UV-Vis DRS）等表征其材料性能。考察了催化材料在40W汞灯辐照下催化降解甲基橙的催化性能。实验结果表明,MoO3的掺入量为15%（摩尔分数）时,材料的光催化性能最优。     

Chemical compositions and optical properties of HfOxNy thin films at different substrate temperatures

High-k HfO_xN_y thin films have been grown by radio frequency (rf) reactive sputtering of metal Hf target in N₂/Ar/O₂ ambient at different substrate temperatures. The chemical compositions of the films have been investigated as a function of substrate temperature by X-ray photoelectron spectroscopy (XPS). XPS measurements showed that nitrogen concentration increases with an increase in substrate temperature. Room-temperature spectroscopic ellipsometry (SE) with photon energy 0.75–6.5 eV was used to investigate the optical properties of the films. SE results demonstrated that refractive index n increases with an increase in substrate temperature. Based on TL parameters which were obtained from the best fit results used in a simulation of the measured spectra, meanwhile, we conclude that the energy band gap (E_g) decreases with an increase in substrate temperature.     

直流磁控溅射法制备非晶态氧化钒薄膜光学特性研究

研究了直流反应磁控溅射工艺中衬底温度对氧化钒(V2O5)薄膜性能的影响,利用X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、X射线衍射(XRD)和紫外-可见光分光光度计(UV1700)分别对薄膜进行了表征.实验结果表明,除了组分和晶态,薄膜的形貌和光学性能受衬底温度的影响很大.随着衬底温度的升高,膜表面变得粗糙,膜厚减小.光学特性测试表明,当衬底温度从160℃升高到320 ℃,光学带隙从2.39 eV下降到2.18 eV.