CO2激光化学气相沉积a-Si:H薄膜

用输出功率为50W的CW CO2激光照射纯硅烷(SiH4)气体得到了a-Si:H薄膜。沉积速率达到200/min。用电子衍射方法测定了所沉积的薄膜是非晶态的。测量了薄膜的光电导率和暗电导率,其比值达104量级。用紫外可见光谱分析了薄膜的光学性质,计算出光能隙为1.44～2.0eV。得到了沉积速率、光电导率、暗电导率、光学能隙随基片温度变化的关系曲线。阐述了CO2激光化学气相沉积a-Si:H薄膜的机理。     

HfO2薄膜的亲疏水性对石墨烯沉积的影响

研究了在不同表面润湿性的HfO₂薄膜上沉积石墨烯的质量,判断了不同表面能大小碳原子的沉积方向。采用电子束工艺制备不同生长时间的HfO₂薄膜,经过静态接触角测量可知,所有HfO₂薄膜均为疏水性,且随着薄膜厚度的增加,表面疏水性加强。再通过等离子体化学气相沉积工艺在HfO₂样品表面制备石墨烯薄膜。通过拉曼测试得出,表面中性润湿性基底对于碳沉积密度贡献不大;表面微疏水性基底对于碳原子总沉积量增益不大,但是对于形成sp²轨道的碳碳双键则增强明显,原因主要是由于碳原子在表面横向迁移的作用增强,从而形成大面积石墨烯薄膜。     

化学气相沉积法可控制备石墨烯薄膜和单晶畴北大核心

采用化学气相沉积（CVD）法,以铜箔为衬底,以甲烷为碳源,制备了石墨烯薄膜和单晶畴,并利用扫描电子显微镜、光学显微镜、喇曼光谱仪、紫外-可见透过光谱仪等手段对石墨烯进行了系统表征。结果表明,质量分数为10%的稀硝酸对铜箔表面进行腐蚀处理20 s可以有效去除铜箔表面析出的杂质颗粒,从而提高石墨烯的质量。在此基础上,研究了氢气和甲烷体积流量比对石墨烯生长的影响,当氢气和甲烷体积流量比从0∶1变化到5∶1时,石墨烯薄膜从单层生长变化到多层生长。此外,氢气和甲烷体积流量比也会显著影响晶畴的形状,随着氢气和甲烷体积流量比的增加,石墨烯晶畴从无规则形状逐渐变化到六边形。     

射频溅射SiO2在制造Si/SiGeHBT中的应用

The principle and technique of RF sputtering SiO₂ were intr oduced and the SiGe/Si HBT using the SiO₂ films were characterized.     

激光化学气相沉积法制备TiO2薄膜

利用激光化学气相沉积(LCVD)方法,以钛金属有机化合物为前驱体,以O2为反应气体,在激光功率PL为0～200 w、基板预热温度为400～700℃的条件下,制备出了金红石型TiO2薄膜和金红石型与锐钛矿型混合TiO2薄膜.研究表明,激光功率和基板预热温度对所沉积的TiO2薄膜的物相组成、截面组织,表面形貌和薄膜生长速度均有着显著的影响.     

电沉积法制备PANI/MnO_2/石墨烯复合材料及其电化学性能研究

采用简便的脉冲电沉积方法一步合成了呈现层-层分布的三维立体结构的PANI/MnO_2/石墨烯三元复合材料,利用XRD和FT-IR等研究了复合物的结构和组成,SEM和TEM表征了复合物的形貌。同时,通过恒流充放电和循环伏安测试研究了该复合物的电化学性能。结果表明,0.5 A·g~(–1)电流密度下的比容量可达1 120 F·g~(–1),且1 000次循环的稳定性高达99%。出色的超电容性能主要源于石墨烯作为基体,其上均匀分布棒状结构的PANI,MnO_2纳米粒子均匀分布于PANI纳米棒上,形成了一种分级的特殊结构。     

化学气相沉积法制备BN

根据国内外现有的文献资料，介绍了化学气相沉积ＢＮ的具体制备方法、试验设备及主要原理。     

激光化学气相沉积法制备铜膜的性能与形态分析

本文对以二（乙酰丙酮根）合铜（Ⅱ）和二（三甲基乙酰三氟代丙酮根）合铜（Ⅱ）为母体的化合物，用１０．６μｍ和２８０ｎｍ激光气相沉积法生成铜膜的形态及性能采用探针轮廓仪，扫描电子显微镜和四探针法进行了分析，观察到紫外激光生成铜膜中具有环状周期性图案的现象。     

化学气相沉积可控制备超薄二维MoS_2纳米片

采用化学气相沉积(CVD)技术,以硫粉和MoO_3为反应剂、氩气为载气,在SiO_2/Si衬底上制备超薄二维MoS_2纳米片。采用扫描电子显微镜(SEM)、原子力显微镜(AFM)、透射电子显微镜(TEM)、喇曼光谱和光致发光光谱测试分析技术,研究硫粉送入距离对超薄MoS_2纳米片的形貌、结构和光学性质的影响规律。结果表明:硫粉送入距离为17～25 cm时,距离MoO_31 cm的SiO_2/Si衬底上形成平行于衬底生长的二维MoS_2纳米片;硫粉送入距离为25～29 cm时,MoO_3正上方的SiO_2/Si衬底上形成竖直排列的二维MoS_2纳米片。通过调控硫粉送入距离和衬底的位置可以控制MoS_2的形成过程,实现水平排列和垂直排列二维MoS_2纳米片的可控生长。     

化学气相沉积TiO2薄膜的XPS研究

通过XPS分析了TiO2薄膜的结构。薄膜是通过化学气相沉积的方法生长，有机源遇热发生分解，沉积在硅衬底上形成TiO2薄膜。XPS分析表明：所得TiO2薄膜含有Ti,C,O,Al,Si元素。各元素的电子结合能与理论值并无太大的偏移，说明通过化学气相沉积法制备的TiO2薄膜，纯度高，质量好，晶型为锐钛矿。     

Laser-induced self-organization of nano-wires on SiO2/Si interface

Original observation of new graded band gap structures formed on the surface of elementary Si semiconductor at studying the optical properties of Si nano-hills formed at the SiO₂/Si interface by pulsed Nd:YAG laser irradiation is reported. The self-organized nano-hills on Si surface are characterized by a strong photoluminescence in the visible range of spectrum with a shoulder extended to the long-wave part of the spectrum. The feature is explained by the quantum confinement effect in nano-hills-nano-wires of gradually changing diameter.     

铜衬底上热丝CVD法低温生长石墨烯薄膜的研究

以乙炔作为碳源,抛光铜片作为衬底,采用热丝CVD法低温生长了石墨烯。通过拉曼散射光谱和紫外-可见分光光度计分析了样品的性能。结果表明,灯丝温度的提高有助于乙炔分解为对石墨烯晶粒形核生长比较有利的含碳活性基团。衬底温度的升高增强了铜衬底对石墨烯生长的催化作用。通过调整气体流量中乙炔的比例,可以有效降低石墨烯薄膜的层数。最终在乙炔浓度为2%,衬底温度为450℃的低衬底温度条件下制得了的单层石墨烯纳米晶薄膜。     

Electroluminescence from Au/Si/SiO2/p-Si structure

Si/SiO₂ films have been grown using the two-target alternation magnetron sputtering technique. The thickness of the SiO₂ layer in all the films was 8 nm and that of the Si layer in five types of the films ranged from 4 to 20 nm in steps of 4 nm. Visible electroluminescence (EL) has been observed from the Au/Si/SiO₂/p-Si structures at a forward bias of 5 V or larger. A broad band with one peak 650–660 nm appears in all the EL spectra of the structures. The effects of the thickness of the Si layer in the Si/SiO₂ films and of input electrical power on the EL spectra are studied systematically.     

SOI planar photonic crystal fabrication: Etching through SiO2/Si/SiO2 layer systems using fluorocarbon plasmas

Dry plasma etching of sub-micron structures in a SiO₂/Si/SiO₂ layer system using Cr as a mask was performed in a fluorocarbon plasma. It was determined that the best anisotropy could be achieved in the most electropositive plasma. A gas composition yielding the desired SOI planar photonic crystal structures was optimized from the available process gases, Ar, He, O₂, SF₆, CF₄, c-C₄F₈, CHF₃, using DC bias data sets. Application of the c-C₄F₈/(noble gas) chemistry allowed fabrication of the desired SOI planar photonic crystal. The average etching rates for the pores and ridge waveguide regions were about 71 and 97 nm/min, respectively, while the average SiO₂/Si/SiO₂ to Cr etching selectivity for the ridge waveguide region was about 33:1 in case of the c-C₄F₈/90%Ar plasma with optimized parameters.     

Characterization of ultra-thin SiO2 by capacitance-voltage and charge pumping measurements

In this paper, we present results on electrical measurements of ultra thin SiO₂ layers (from 3.5 nm down to 1.7 nm), used as gate dielectric in metal-oxide-semiconductors (MOS) devices. Capacitance-voltage (C-V) measurements and simulations on MOS capacitors have been used for extracting the electrical oxide thickness. The SiO₂/Si interface and oxide quality have been analyzed by charge pumping (CP) measurements. The mean interface traps density is measured by 2-level CP, and the energy distribution within the semiconductor bandgap of these traps are investigated by 3-level charge pumping measurements. A comparison of the energy distribution of the SiO₂/Si interface traps is made using classical and quantum simulations to extract the surface potential as a function of the gate signal. When the gate oxide thickness <3.5 nm, we prove that it is mandatory to take into account the quantum effects to obtain a more accurate energy distribution of the SiO₂/Si interface traps. We also explain the increase of the apparent interface traps density measured by 2-levels CP with the increase of the oxide thickness, for transistors made from the same technological process.     

基于PECVD的SiO2薄膜制备研究进展

二氧化硅(SiO₂)薄膜因其卓越的光学性能,在半导体器件、集成电路、光学涂层等领域具有巨大的应用潜力。然而,SiO₂薄膜制备过程中面临表面粗糙度、杂质控制和致密性等问题。为解决这些问题,研究者们通过工艺改进和表面修饰等手段来提高SiO₂薄膜的性能。在众多SiO₂薄膜制备技术中,等离子体增强化学气相沉积(Plasma-Enhanced Chemical Vapor Deposition, PECVD)技术由于沉积SiO₂薄膜所需温度低、原位生长等优势,成为制备SiO₂薄膜最常用的方法。综述了用PECVD技术制备SiO₂薄膜的发展历程,并探讨了关键工艺参数和后处理工艺对薄膜质量的影响。对PECVD技术的深入研究,有助于实现对SiO₂薄膜生长的更精准控制,进一步拓展其广泛的应用前景。     

Low-temperature deposition of SiO2 films using plasma-enhanced oxygen with reduction of oxygen-originated damage

Plasma-enhanced chemical vapor deposition of SiO₂ with well-suppressed subcutaneous oxidation is demonstrated to be a promising technology for eliminating defect generation and fabricating thin gate SiO₂ films by means of a totally low-temperature process. An anomalous increase in electron density was observed in Si substrates irradiated by plasma-activated oxygen during the formation of gate SiO₂ films using an ultrahigh-vacuum system. The origin of this phenomenon was related to the donors generated by a high-energy species of oxygen radicals. For a deposition process, ionized oxygen may be effective but the radicals may cause plasma-enhanced oxidation with defect generation.     

ReSe2薄膜的盐助生长及其光电特性研究

二硒化铼(ReSe2)因具有较好的红外光响应和各向异性特性而成为近年来的研究热点.采用盐辅助化学气相沉积技术,在SiO2/Si衬底上成功合成了大面积的单层ReSe2薄膜,其尺寸达到80μm.采用拉曼光谱(Raman)、光致发光光谱(PL)、原子力显微镜(AFM)和X射线光电子能谱(XPS)等手段对制备的ReSe2薄膜样品进行了形貌、光谱、厚度和元素成分的表征,结果表明所制备的ReSe2薄膜晶体质量高.基于单层ReSe2薄膜构筑了场效应晶体管,系统研究了其光电特性,结果显示器件的响应时间达毫秒级.     

Photoluminescent properties of ZnO thin films grown on SiO2/Si(100) by metal-organic chemical vapor deposition

We report on the photoluminescent (PL) properties of ZnO thin films grown on SiO₂/Si(100) substrates using low pressure metal-organic chemical vapor deposition. The growth temperature of the films was as low as 400°C. From the PL spectra of the films at 10–300 K, strong PL peaks due to free and bound excitons were observed. The origin of the near bandedge emission peaks was investigated measuring temperature-dependent PL spectra. In addition, the Zn O films demonstrated a stimulated emission peak at room temperature. Upon illumination with an excitation density of 1 MW/cm², a strong, sharp peak was observed at 3.181 eV.