Ar气氛下退火处理对6H-SiC晶片表面结构的影响

本文对物理气相传输法生长的三片2英寸掺氮6H-SiC晶片,分别在不同温度下进行退火处理.采用原子力显微镜(AFM)对SiC晶片表面结构进行表征,研究了不同温度和偏角度对SiC晶片表面结构的影响.发现Ar气氛下高温退火处理可以在晶片表面形成规则的台阶条纹,说明Ar气氛下的高温退火处理对SiC晶片表面有一定的刻蚀作用.     

提拉法Ti:LiAlO2晶体的生长、缺陷及N2退火研究

本文采用提拉法成功地生长了钛掺杂浓度为0.1%原子分数的LiAlO2单晶体,借助光学显微镜,结合化学腐蚀法,对Ti:LiAlO2晶体(100)面空气退火前后的缺陷特征进行了研究,用AFM观测了(100)面晶片在不同温度下流动N2气氛退火过的表面形貌。结果表明:Ti:LiAlO2晶体(100)面的位错腐蚀坑是底面为平行四边形的锥形坑,位错密度约为5.0×104cm-2,900℃空气退火后晶片表面的位错腐蚀坑变大;N2退火能显著影响晶片的表面形貌,当退火温度为900℃时,晶片的均方根粗糙度(RMS)达到最低值。     

影响化学机械抛光4H导电SiC晶片表面质量的关键参数研究

选用二氧化硅抛光液抛光4H导电SiC晶片表面,探究影响SiC晶片表面质量的关键参数,获得更高的去除效率和表面质量.实验结果表明,SiC表面的氧化是氢氧根离子和双氧水共同作用的结果.保持压力不变并增加氢氧根离子或双氧水的含量,SiC表面去除速率先增加后保持不变.在更大的压力下增加氢氧根离子的含量,SiC表面的抛光去除速率进一步增加.通过优化的抛光参数,SiC表面的抛光去除速率达到142 nm/h.进一步研究结果表明,保持化学机械抛光过程中氧化作用与机械作用相匹配,是获得高抛光效率和良好的表面质量的关键.表面缺陷检测仪(Candela)和原子力显微镜(AFM)的测试结果表明,SiC抛光片表面无划痕,粗糙度达到0.06 nm.外延后总缺陷密度小于1个/cm2,粗糙度达到0.16 nm.     

阳离子表面活性剂对A向蓝宝石晶片化学机械抛光效率的影响

为了探究阳离子表面活性剂对A向(1120)蓝宝石晶片化学机械抛光效率的影响,采用失重法计算蓝宝石的材料去除率(MRR)、原子力显微镜观察抛光后蓝宝石晶片表面粗糙度(Ra).结果表明:纯二氧化硅磨粒抛光液中,蓝宝石晶片的MRR在pH8时最优(MRR=1984/h),此时Ra为0.867 nm;添加一定浓度的阳离子表面活性剂可以提高蓝宝石晶片的抛光效率,其MRR在pH =9时达到最大(MRR=2366 nm/h),此时Ra =0.810 nm.通过粒径和Zeta电位分析,阳离子表面活性剂改变了二氧化硅磨粒表面的Zeta电位值,进而改变了磨粒与磨粒及磨粒与蓝宝石晶片的作用力,且在碱性条件下可以获得较高的MRR.     

用PECVD在低温衬底上制备类金刚石碳膜

本文报道用 RF PECVD在低温衬底上制备了类金刚石碳(DLC)膜.研究了氢稀释、气体压力和 RF 功率对薄膜性质的影响. 用光透射率、红外吸收谱和小角度X射线衍射谱分析了DLC膜的结构和光学性质.结果表明,这样制备的DLC膜是无定形态的,包含了大量的C-H键,具有良好的透明性.厚度为230nm的DLC膜在480nm后的可见光区和近红外区的透过率大于83;,所导出的Tauc光学带隙在2.7eV和3.7eV之间.本文还探讨了应用这种DLC膜作为二次电子发射材料的可能性.     

β-BBO薄膜的液相外延生长

采用液相外延法在掺Sr2+的α-BBO(001)衬底上进行了生长β-BBO薄膜的实验,生长出表面光滑、无色透明的薄膜.应用X射线粉末衍射(XRD)、分光光谱仪和原子力显微镜(AFM)对外延膜进行了分析测试.结果表明,所制备的β-BBO薄膜择优取向为(001)面,在1μm×1μm的面积内,外延膜的表面粗糙度为2.279nm,其紫外吸收边同β-BBO单晶一样也为190nm,但外延膜的透过率略有下降.采用调Q脉冲Nd: YAG激光器观察了β-BBO外延膜的倍频效应.     

高温超导薄膜衬底材料LaAlO3单晶的超光滑表面抛光研究

本文以化学机械抛光为手段,以原子力显微镜(AFM)为工具,对高温超导薄膜衬底材料LaAlO3单晶的超光滑表面抛光进行研究.既观察到了由传统光学表面向超光滑表面过渡的过程,又观察到了超光滑表面加工的结果-表面的本征化.显示了超光滑表面抛光对外延衬底表面的重要性.     

HgInTe晶片表面化学抛光研究

对HgInTe(MIT)晶片表面化学抛光工艺进行了研究,采用不同浓度的Br2-C3H7ON以及Br2-MeOH作为抛光液对MIT晶片进行化学抛光后发现,5;Br2-C3H7ON抛光液的抛光速度平稳且易于控制,抛光3min后可以有效去除表面划痕,获得光亮表面,表面形貌达到最佳效果.AFM分析结果表明,5;Br2-C3H7ON抛光后的晶片表面粗糙度降低67;,平整度显著增加.相比之下,5;Br2-MeOH抛光液抛光速度过快,抛光后的表面形貌较差.     

表面处理对蓝宝石衬底的影响

蓝宝石衬底是目前最为普遍的一种衬底材料,是生长GaN、ZnO材料最常用的衬底.本文用光学显微镜、原子力显微镜(AFM)和高分辨X射线双晶洐射对蓝宝石衬底进行了分析测试,系统研究了经过机械抛光、化学机械抛光、化学腐蚀等表面处理对蓝宝石衬底表面性能的影响.结果表明经过化学机械抛光随后再经腐蚀后的蓝宝石衬底的表面性能最好.     

CMTD晶体的分解过程原子力显微镜实时观测研究

用原子力显微镜实时观测了有机晶体CMTD(CdHg(SCN)4(H6C2OS)2)的表面分解过程,这一分解过程是以表面形貌变化来表征的,并且能反映分解过程中的一些固态反应的物理一化学变化机制.X射线能谱分析(EDAX)表明,相对于新鲜的CMTD晶体,在分解物中Hg低而S高;X射线衍射(XRD)表明分解物为非晶态;红外吸收光谱(IR)表明在CMTD晶体结构中的(H6C2OS)结构基元被分解为H2O和酸;量热分析(DSC)表明CMTD晶体在室温空气中确实有化学反应发生.本文用原子力显微镜实时记录了这一分解过程的形貌变化,发现这种非晶态的分解物的产生过程为:成核一核生长一核分散等.这是首次用原子力显微镜实时观测到这种分解过程.     

高质量非晶金刚石薄膜的制备研究

利用自行研制的磁过滤等离子体技术(FCAP),并创造性地对衬底施加低频率周期性负偏压,在室温下的单晶硅表面上制备了高质量的非晶金刚石薄膜。用扫描电子显微镜(SEM),原子力显微镜(AFM),红外吸收光谱(IR),纳米硬度计和摩擦试验仪对制备的非晶金刚石薄膜进行了结构和性能表征。实验结果表明:制备的非晶金刚石薄膜表面十分光滑,表面粗糙度仅为0.1nm;薄膜中sp3键成份高达70.7%,对应薄膜硬度达到74.8GPa,接近金刚石的硬度;薄膜摩擦系数在0.12~0.16之间。文中也讨论了偏压类型对沉积薄膜结构的影响。     

Systematic study of various stages during the growth process of diamond-like carbon film by atomic force microscopy

The diamond like carbon (DLC) films have been grown by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) in methane-argon plasma. In PECVD, the plasma sheath potential drop arising due to argon plasma was utilized to grow the DLC film on silicon (100) substrate at low temperature without using any external negative bias voltage. The growth process of the DLC film has been studied completely starting from nucleation to continuous film by atomic force microscopy. It was seen that the DLC film nucleates around surface defects on the substrate and that the film growth occurs by both adatom deposition and coalescence between nucleated islands. Raman spectrum confirms that the DLC film nucleates excessively in sp² hybridized state and that during the growth process the fraction of sp³ CH_x (x = 1 − 3) increases which leads to the amorphous nature of the film. Long range uniformity of the film was identified using scanning electron microscope.     

Microstructure of interfacial HgTe/CdTe superlattice layers for growth of HgCdTe on CdZnTe (2 1 1)B substrates

Transmission electron microscopy has been used to characterize the microstructure of HgTe/CdTe superlattices (SLs) grown by molecular beam epitaxy on CdZnTe(2 1 1) B substrates. The purpose of these intermediate layers was to improve the quality of subsequent HgCdTe (MCT) epilayers intended for infrared detectors. The observations confirmed that the SLs smoothed out the surface roughness of the substrate, and showed that threading dislocations were prevented from reaching the MCT epilayers. High-quality growth of MCT on CdZnTe using the HgTe/CdTe interfacial layers has been demonstrated.     

Electron beam induced surface modification of amorphous Sb2Se3 thin film

The change in the surface morphology of amorphous Sb₂Se₃ thin films during the electron beam irradiation has been studied mainly by atomic force microscopy (AFM). Electron beam at accelerating voltages 30 kV is focused onto the surface of the specimens of 100-μm thickness, and then the surface morphology of each specimen has been observed by AFM in air. The modification of the film surface includes lateral and vertical resizing which is typically in the micrometer and sub-micrometer range. Protrusions above the surface as high as 90 nm are observed at 180 pA electron beam current, whilst trenches as deep as 97 nm are observed at 800 pA electron beam current (total thickness of thin film is 100 nm). The dependence of patterns characteristics on irradiation parameters such as exposure time and beam current has also been studied. Physical mechanisms for trench and mound formation are proposed.     

ZnO压电薄膜的制备与性能表征

采用射频磁控溅射法在硅(100)衬底上制备高质量的ZnO压电薄膜.利用X射线衍射仪(XRD)、原子力显微镜(AFM)、压电响应力显微镜(PFM)等仪器研究了薄膜成分,表面形貌和压电性质.结果表明:实验制备的ZnO薄膜具有很好的压电性质,c轴取向和表面粗糙度对薄膜压电特性有很大影响,高度c轴取向生长和表面粗糙度较小的ZnO薄膜表现出更好的压电性质.     

两步法溅射中缓冲层厚度对Ge薄膜质量的影响

采用低温缓冲层技术制备Ge薄膜,利用AFM和Raman光谱研究缓冲层厚度对低温Ge缓冲层残余应变弛豫的影响.实验结果显示:随着缓冲层厚度的增加,残余应变弛豫度增大.在30 nm厚的低温Ge缓冲层上生长800nm厚的Ge外延层.Ge薄膜具有良好的结晶性,表面粗糙度RMS为2.06 nm.     

蓝宝石衬底上磁控溅射法室温制备外延ZnO薄膜

在室温条件下,采用磁控溅射方法在蓝宝石(0001)衬底上制备了外延的ZnO薄膜.采用原子力显微镜(AFM)、X射线衍射仪(XRD)、可见-紫外分光光度计系统研究了ZnO薄膜微观结构和光学特性.AFM测量结果表明ZnO薄膜具有较为均匀的ZnO晶粒,表面平整,具有较小的均方根粗糙度(0.9 nm);X射线衍射结果表明制备的ZnO薄膜为具有六角纤锌矿结构的外延薄膜;光学透射谱显示样品在可见光范围内具有较高的透过性,并在370 nm附近出现一个较陡的吸收边,表明在室温下制备出了具有较高质量的ZnO薄膜.     

昆明物理研究所分子束外延碲镉汞薄膜技术进展

碲镉汞(MCT)自从问世以来一直是高端红外(IR)探测器领域的首选材料,分子束外延碲镉汞技术具有低成本异质外延、材料能带精准调控、原位成结等优势,是第三代红外焦平面陈列(FPA)器件研制的重要手段。本文报道了昆明物理研究所分子束外延(MBE)MCT薄膜技术进展,包括材料结构、晶体质量、表面缺陷、材料均匀性、掺杂浓度等参数优化控制的研究结果。异质衬底、碲锌镉衬底上MCT薄膜尺寸分别为4英寸(10.16 cm)及2.5 cm×2.5 cm,材料EPD值分别在1×10⁶ cm^-2附近及(3~30)×10⁴ cm^-2范围,表面宏观缺陷密度分别在30 cm^-2附近及100~300 cm^-2范围,薄膜质量与国内外先进水平相当。采用分子束外延MCT薄膜实现了2 048×2 048中波红外(MWIR)、2 048×2 048短波甚高分辨率红外(SWIR)焦平面、640×512中短双色红外(S-MWIR)、320×256中中双色红外(M-MWIR)FPA探测器的研制和验证。     

Determination of the electrical properties of 2.5 nm thick silicon-based dielectric films: thermally grown SiOx

Ultra-thin (<5 nm thick) thermal oxide and oxynitride films with different compositions are candidates for complementary metal/oxide/semiconductor technology in ultra-large-scale integration (ULSI) applications. The latter are expected to offer the best compromise between nitrides and oxides. The aim of this work is to measure the electrical properties of a leaky 2.5 nm thick thermally grown oxide film using the high frequency capacitance–voltage (HF C(V)) measurements. The cleanliness and the surface roughness of the Si(1 0 0) surface were measured prior to in situ oxidation by means of, respectively, Auger electron spectroscopy (AES) and atomic force microscopy (AFM). The physical–chemical properties of the thermal oxide film were measured by AES (film thickness, composition), Fourier transform infrared spectroscopy (FTIR) (composition, vibration modes), cross-sectional transmission electron microscopy (TEM) (film thickness, homogeneity) and electron energy loss spectroscopy (EELS) (gap width determination). The results are compared to those obtained for the native oxide film and a chemical oxide film. The latter was first grown on the silicon substrate to prevent contamination and surface disorder after flash heating in vacuum prior to oxide growth. The substrate Si(1 0 0) surface cleaned in ultra-high vacuum (UHV) was then oxidized in a 10⁻³ mbar oxygen (O₂) gas pressure at 900°C to get the 2.5 nm thick oxide film. The grafting of a self-assembled insulating monolayer (SAM) of organic molecules on the grown oxide film permits us to obtain analysable capacitance as a function of voltage data. Indeed, this monolayer made up of octadecyltrichlorosilane molecules leads to a reduction of the leakage current through the aluminium/self-assembled monolayer/oxide/silicon heterostructure. The resulting current as a function of voltage data were compared to those of a standard 2.5 nm thick oxide film. The method proposed here to extract the electrical parameters of the thermal oxide film is demonstrated to be valid. We show mainly that the reduction of the leakage current through the aluminium/self-assembled monolayer/thermal oxide/silicon heterostructure is seven orders of magnitude bigger than in the case of the native oxide film.     

缓冲层ZnPc对有机电致发光器件特性的影响

本文研究了酞菁锌(ZnPc)薄膜的表面形貌及ZnPc薄膜作为缓冲层对有机电致发光器件(OLEDs)光电特性的影响.对比两组样品的AFM图像,ZnPc薄膜相比于ITO薄膜,其表面的岛面积较大,薄膜表面更连续平整,基本上覆盖了ITO膜表面针孔,减少了表面的缺陷.另外,ZnPc薄膜的岛分布均匀有序.使用ZnPc作为缓冲层的器件性能明显好于未使用ZnPc修饰的器件,在7.42V的驱动电压下的最大发光亮度达到1.428kcd/m2,在4.3V电压驱动下时,最大光功率效率为1.411m/W;而未使用缓冲层的器件在8V的驱动电压下达到最大发光亮度达到1.212kcd/m2,在5.5V电压驱动下时,最大光功率效率为0.931m/W.