用ECR氮等离子对纳米TiO2薄膜光谱响应改性的研究

采用ECR氮等离子对纳米TiO2薄膜表面进行氮注入处理来改善纳米TiO2催化剂的光谱响应范围。处理后表面颜色变成微黄色，说明氮离子已注入到TiO2薄膜里；AFM观察处理前后的薄膜，发现表面形貌没有很大改变；紫外—可见光谱分析结果表明，TiO2薄膜催化剂的光谱响应红移了12—18nm；通过不同功率、不同处理时间研究显示，在微波功率为400W、处理60min改性效果最理想。     

高压强下GaN的结构相变及电子结构的第一性原理研究

基于密度泛函理论的平面波赝势方法,选择广义梯度近似(GGA)下的PBE算法-关联泛函对GaN晶体结构、能带结构以及电子态密度随压强的变化进行了研究,并计算出GaN材料的相变点压强值。研究结果表明:随着压强增加,常见的纤锌矿与闪锌矿GaN会发生结构相变成岩盐矿结构,并且其能带结构均由直接带隙转变成间接带隙。其中,通过焓相等原理得到纤锌矿到岩盐矿结构的相变压强为44.4GPa,而闪锌矿到岩盐矿结构的相变压强为43.6GPa。此外,随着压强增大,GaN纤锌矿、闪锌矿和岩盐矿的价带态密度均向低能方向偏移,而导带态密度向高能方向偏移,从而导致GaN共价性增强及带隙随压强增大而展宽。     

等离子体辅助有机金属(CH_3)_3Ga化学气相沉积GaN薄膜

采用ECR等离子体辅助技术,融合化学气相沉积法,在450℃的相对低温条下于Si(100)衬底上生长出GaN薄膜.对样品进行了XRD、FT-IR和AFM表征,并在制备过程中采集到反应室中N_2-(CH_3)_3Ga等离子体的发射光谱.结果表明,所制备的多晶体GaN薄膜是由N_2-(CH_3)_3Ga等离子体中的活性成分通过复杂的反应生成的,其生长过程符合岛状生长机制.     

A Study of Diamond-Like Carbon Thin Films Prepared by Microwave Plasma Chemical Vapour Deposition

In order to deposit good films, we need to study the uniformity of plasma density and the plasma density under different gas pressures and powers. The plasma density was diagnosed by a Langmuir probe. The optical emission spectroscopy （OES） of CH4 and H2 discharge was obtained with raster spectroscopy, with characteristic peaks of H and CH achieved. Diamond-like carbon films were achieved based on the study of plasma density and OES and characterized by atomic force microscope （AFM）, X-ray diffraction instrument （XRD）, Raman spectroscope and profiler.     

低温等离子体气相沉积氮化镓薄膜的光谱特性研究

采用低温等离子体增强化学气相沉积工艺,以氮气N2和三甲基镓(TMG)为反应气源,在蓝宝石衬底-αAl2O3的(0001)面上低温生长了GaN薄膜。薄膜光致发光光谱(PL)出现两个发光带,一个是中心位置位于364nm的锐而强的带边峰。另一个是中心波长在550nm(2.2eV),范围在480~700nm的强而宽的黄光发光带。傅立叶红外光谱(FTIR)观察到GaN的A1(LO)的下沿峰和E1(TO)峰,说明这是六方结构的GaN薄膜。     

Spatial Distribution of ECR Plasma Density in ECR-PECVD Reaction Chamber

The spatial distribution of Electron Cyclotron Resonance （ECR） plasma in the ECRPlasma Enhanced Metalorganic Chemical Vapour Deposition （ECR-PECVD） reaction chamber is diagnosed by a Langmuir probe. The uniformity is also investigated. The results show that the ECR plasma in the upper region of the reaction chamber under the influence of magnetic field has poor radial and axial uniformity. However, the plasma in the downstream region of the reaction chamber has fine radial uniformity. This excellent uniform plasma in the downstream has extensive application in plasma process.     

Ion Density Distribution in an Inductively Coupled Plasma Chamber

The ion density distribution in the reaction chamber was diagnosed by a Langmuir probe. The rules of the ion density distribution were obtained under the pressures of 9 Pa, 13 Pa, 27 Pa and 53 Pa in the reaction chamber, different radio-frequency powers and different positions. The result indicates that the ion density decreases as the pressure increases, and increases as the power decreases. The ion density of axial position z =0 achieves 5.8×1010 on the center of coil under the power of 200 w and pressure of 9 Pa in the reaction chamber.     

Optical Emission Spectroscopy of Electron Cyclotron Resonance-Plasma Enchanced Metalorganic Chemical Vapor Deposition Process for Deposition of GaN Film

An investigation was made into the nitrogen-trimethylgallium mixed electron cyclotron resonance （ECR） plasma by optical emission spectroscopy （OES）. The ECR plasma enhanced metalorganic chemical vapour deposition technology was adopted to grow GaN film on an α-Al2O3 substrate. X-ray diffraction （XRD） analyses showed that the peak of GaN （0002） was at 20 = 34.48°, being sharper and more intense with the increase in the Ne： trimethylgallium（TMG） flow ratio. The results demonstrate that the electron cyclotron resonance-plasma enchanced met- alorganic chemical vapor deposition （ECR-MOPECVD） technology is evidently advantageous for the deposition of GaN film at a low growth temperature.     

感应耦合等离子体干法刻蚀锑化铟薄膜研究

应用感应耦合等离子体技术首次实现了对锑化铟薄膜的干法刻蚀。朗缪尔探针诊断结果表明 :射频电源功率为 2 0 0 W时 ,在刻蚀样品附近的等离子体离子密度最大达 6.71 70× 1 0 1 0 cm- 3。以 CCl F2 为刻蚀气体 ,进气流量 2 m L/min,RF功率 2 0 0 W,等离子体反应刻蚀运行气压 7.98Pa时 ,对 In Sb-In薄膜进行了感应耦合等离子体干法刻蚀 ,获得刻蚀图形 ,宽深比为 5     

气压对离子源增强磁控溅射制备氮化铝薄膜的影响

目的 制备性能优异的氮化铝薄膜.方法 采用射频感应耦合离子源辅助直流磁控溅射的方法 制备氮化铝薄膜,在不同的气压下,在Si(100)基片和普通玻璃上生长了不同晶面取向的氮化铝薄膜.使用X射线衍射仪(XRD)、场发射扫描电镜(FESEM)、原子力显微镜(AFM)分析氮化铝薄膜的结构、晶面取向、表面形貌及薄膜表面粗糙度,使用紫外可见分光光度计测定薄膜的透过率,并计算薄膜的禁带宽度.研究气压的大小对磁控溅射制备氮化铝薄膜微观结构的影响.结果 在各气压下,薄膜生长以(100)面取向为主.在0.7Pa前,(100)面的衍射峰强度逐渐增强,0.7 Pa之后减弱.(002)面衍射峰强度在0.6Pa之前较大,0.6Pa之后变小.各气压下薄膜表面均方根粗糙度均小于3nm,且随着气压的增大先增大后减小,0.7 Pa时最大达到2.678nm.各气压下所制备薄膜的透过率均大于60%,0.7Pa时薄膜的禁带宽度为5.4eV.结论 较高气压有利于(100)晶面的生长,较低气压有利于(002)晶面的生长;(100)面衍射峰强度在0.7 Pa时达到最大;随气压的增大,薄膜表面粗糙度先增大后减小;所制备的薄膜为直接带隙半导体薄膜.