在复合衬底γ-Al2O3/Si(001）上生长GaN

采用分子束外延（MBE）生长方法，使用γ-Al₂O₃材料作为新型过渡层，在Si(001）衬底上获得了没有裂纹的GaN外延层，实验结果表明使用γ-Al₂O₃过渡层有效地缓解了外延层中的应力. 通过生长并测试分析几种不同结构的外延材料，研究了复合衬底γ-Al₂O₃/Si (001）生长GaN情况，得到了六方相GaN单晶材料，实现了GaN c面生长. 预铺薄层Al及高温AlN层可以提高GaN晶体质量，低温AlN缓冲层可以改善GaN表面的粗糙度. 为解决Si(001）衬底上GaN的生长问题提供了有益的探索.     

锗单晶在酸性SiO2抛光液条件下的抛光机理及加工工艺

该文研究了化学机械抛光(CMP)条件下,锗单晶在含HNO₃的SiO₂抛光液中的腐蚀过程。通过改变抛光时间,分析锗单晶表面状态的变化规律。结果表明,在SiO₂抛光液pH值为1~2时,SiO₂抛光液中存在 Si—OH和 Si—O^-形式;锗单晶先与HNO₃反应生成Ge(NO₃)₄,而后Ge⁴⁺的含氧酸盐会剧烈水解生成Ge—OH,Ge—OH 继续反应并以Ge—OH₂⁺形式存在。由于表面电荷的吸引,Si—O^-和Ge—OH₂⁺在锗单晶表面生成Si—O—Ge软化层,从动力学角度加快了腐蚀速率,促进了表面抛光的程度。抛光时间为15~20 min时,机械抛光和侵蚀的法向速度处于平衡状态,CMP抛光后锗单晶表面粗糙度S_a≤0.8 nm,10倍显微镜下无划痕、麻点。     

4英寸高质量InSb晶体生长研究

InSb晶体是制备中波红外探测器的重要材料。为了满足新一代超大规模阵列红外焦平面探测器的发展需求,开展了大尺寸InSb晶体的生长研究,解决了晶体生长的诸多关键技术,成功地生长出了直径为4 in的高质量InSb单晶,并加工出了高质量的4 in InSb抛光晶片。测试表明,直径大于120 mm的晶体长度超过100 mm,晶体位错密度小于100 cm^-2,其电学参数均匀,载流子浓度、载流子迁移率均满足制备高性能大规格红外焦平面探测器的要求。这为新一代超大规模阵列红外焦平面探测器的发展奠定了良好的材料基础。     

铜CMP碱性抛光液中氧化剂的电化学行为研究

化学机械抛光(CMP)工艺是IC工艺中大马士革工序的关键步骤。抛光液的电化学行为研究对抛光质量的控制具有重要意义。采用电化学测试手段,研究碱性抛光液中氧化剂(H₂O₂)对铜表面钝化膜的成膜影响,分析H₂O₂对抛光速率、表面粗糙度的影响机理。通过实验确定,在0.5% SiO₂磨料和3% 表面活性剂的碱性抛光液中,添加0.5%的H₂O₂和3%的FA/OⅡ型螯合剂可获得大于800 nm/min的高抛光速率和表面粗糙度为22.2 nm的较佳平坦效果。     

Co3O4/Fe2O3异质结复合材料的制备及其紫外光光电探测性能

分别采用旋涂法和水热法在FTO衬底上制备Co₃O₄种子层和Co₃O₄薄膜,再在Co₃O₄薄膜上水热生长Fe₂O₃纳米棒,获得了高质量的Co₃O₄/Fe₂O₃异质结复合材料。通过改变Fe₂O₃前驱体溶液浓度来改变异质结复合材料中Fe₂O₃组分的含量。结果表明,Fe₂O₃纳米棒覆盖在呈网状结构的Co₃O₄薄膜上,随着Fe₂O₃前驱体溶液浓度即Fe₂O₃组分含量的增加,Co₃O₄/Fe₂O₃异质结复合材料对紫外光的响应逐渐增强,当Fe₂O₃前驱体溶液浓度为0.015mol/L时,异质结复合材料有着很好的光电稳定性,并表现出较高的响应率(12.5mA/W)和探测率(4.4×10¹⁰Jones)。     

TiO2基染料敏化太阳能电池的表面修饰及性能研究

采用水热法制备TiO₂浆料,用La(NO₃)₃溶 液浸泡TiO₂薄膜获得修饰电极。用X射线光电子能谱(XPS) 和扫描电子显微镜(SEM)对修饰电极的主要成分及形貌进行表征的结果显示,电极薄膜分为 上下两层,表 面包覆层粒径较大,为La₂O₃颗粒;下层颗粒粒径较小,为TiO₂颗粒。电流-电压测 试结果显示,与修饰 前相比,用La(NO₃)₃溶液浸泡30min获得的膜电极性能最优,使 开路电压和短路电流分别提高了6.8%和 18.5%。电化学阻抗谱(EIS)测试结果表明,相同偏压下,TiO₂/La ₂O₃电极界面复合电阻比TiO₂要大,说明 La₂O₃包覆层在一定程度上抑制了界面的电子复合,改善了电池的光电化学性能。     

插层Al2O3对氧化铪基忆阻器的性能优化及多值特性研究

近年来,氧化铪基忆阻器因其优异的阻变性能及与CMOS工艺兼容等特点而被广泛研究。然而,氧化铪基忆阻器仍存在以下问题:1) 器件良率、可靠性、均一性不足；2) Set和Reset 过程中电流突变,导致多值特性较差。为实现氧化铪基忆阻器的性能优化及多值特性,文章在HfO₂表面生长一层1~5 nm Al₂O₃,构造Al₂O₃/HfO₂双介质层忆阻器,并对HfO₂和Al₂O₃的厚度进行优化,最终得到性能显著提升的Al₂O₃/HfO₂双介质层多值忆阻器。该器件呈现出保持性良好的10个不同电阻态(1×10⁴ s@85℃)。由于氧离子在Al₂O₃层的迁移率更低,限制了氧空位细丝生长速率及宽度,且Al₂O₃具有热增强作用,使氧空位分布更均匀,促使氧空位细丝生成/断裂过程由突变转为渐变。该工作为进一步实现氧化铪基忆阻器的性能优化及多值特性提供了参考。     

降低高k介质层微粒污染的工艺研究

随着集成电路制造技术节点进一步缩减,高k介质层金属栅工艺得到广泛应用。该工艺中,减少高k介质层淀积的微粒污染对后续膜层的生长质量至关重要。采用原子层淀积法生长了高k的HfO₂层。针对高k层表面容易引入微粒污染的问题,采取了改变HfO₂淀积过程反应物H₂O、HfCl₄的脉冲时间和冲洗时间的方法。当H₂O的冲洗时间增加量为3 000 ms时,微粒数量、杂质Cl离子含量显著降低。该工艺研究对实际工艺中高k层的可靠性、合格率的提高和生产成本的降低均有重要价值。     

高质量5 in InSb单晶生长

锑化铟(InSb)焦平面探测器是中波红外探测领域应用广泛的一种探测器。作为制备探测器的基础,InSb晶体材料的质量和性能显得尤为重要。近年来InSb晶体材料在向高质量大尺寸方向发展。通过多举措坩埚设计和温场条件设计,采用直拉法生长了直径大于135 mm的InSb单晶。测试结果表明,5 in晶片的位错腐蚀坑密度小于50 cm^-2,双晶衍射峰的半峰宽为8.32 arcsec,晶体具有相当好的完整性。通过优化生长工艺参数,晶体生长过程中具有较为平坦的固液界面,表现出良好的径向电学均匀性。这为制备低成本和超大规模InSb红外探测器阵列奠定了基础。     

采用Taguchi方法优化一种带外延层的PPD工艺参数

结合水热法和阳极氧化法合成了Sb₂S₃/TiO₂纳米管异质结阵列,采用场发射扫描电子显微镜、X射线衍射谱表征了异质结阵列的形貌和晶体结构。暗态下的电流-电压曲线表明Sb₂S₃/TiO₂纳米管异质结阵列具有整流效应。相比于纯的TiO2纳米管阵列,Sb₂S₃/TiO₂纳米管异质结阵列的光电性能有了显著的提升:在AM 1.5标准光强作用下,光电转换效率从0.07%增长到0.40%,表面光电压响应范围从紫外光区拓宽至可见光区。结合表面光电压谱和相位谱,分析了Sb₂S₃/TiO₂纳米管异质结阵列中光生载流子的分离和传输性能。 更多还原     

Elaboration and characterization of a KCl single crystal doped with nanocrystalsof a Sb2O3 semiconductor

Undoped and doped KCl single crystals have been successfully elaborated via the Czochralski（Cz） method.The effects of dopant Sb₂O₃ nanocrystals on structural and optical properties were investigated by a number of techniques,including X-ray diffraction（XRD）,scanning electron microscopy（SEM）,energy dispersive X-ray（EDAX） analysis,UV-visible and photoluminescence（PL） spectrophotometers.An XRD pattern of KCl:Sb₂O₃ reveals that the Sb₂O₃ nanocrystals are in the well-crystalline orthorhombic phase.The broadening of diffraction peaks indicated the presence of a Sb₂O₃ semiconductor in the nanometer size regime.The shift of absorption and PL peaks is observed near 334 nm and 360 nm respectively due to the quantum confinement effect in Sb₂O₃ nanocrystals.Particle sizes calculated from XRD studies agree fairly well with those estimated from optical studies.An SEM image of the surface KCl:Sb₂O₃ single crystal shows large quasi-spherical of Sb₂O₃ crystallites scattered on the surface.The elemental analysis from EDAX demonstrates that the KCl:Sb₂O₃ single crystal is slightly rich in oxygen and a source of excessive quantities of oxygen is discussed.     

A comparison of liquid and gas phase surface preparation of III-V compound semiconductors for atomic layer deposition

Native oxide removal and surface termination of InAs(1 0 0) and InSb(1 0 0) using liquid and gas phase HF chemistries were studied using X-ray photoelectron spectroscopy. Aqueous HF etching removed the native oxides on InAs and produced elemental As, which reoxidized when exposed to air. On InSb the native oxides were not completely removed due to F-termination, which passivated the surface. Gas phase HF etching of InSb native oxide completely removed Sb₂O₅ producing a stoichiometric semiconductor surface terminated by F atoms on primarily In surface sites. On InAs gas phase HF completely removed As₂O₃ producing two surface stoichiometries. For the majority of HF to water molar ratios studied, a stoichiometric bulk metal and an As-rich overlayer were produced. For a lean HF composition, an As-rich bulk metal and In-rich overlayer were produced. Deposition of Al₂O₃ by atomic layer deposition (ALD) at 170 °C directly onto F-terminated InSb produced a chemically sharp Al₂O₃/InSb interface. ALD of Al₂O₃ on an In-rich overlayer on InAs resulted in an interfacial layer containing As-oxide.     

Growth and crystal quality of inp crystals by the liquid encapsulated czochralski technique

The growth of InP single crystals by the liquid encapsulated Czochralski (LEC) technique has been studied from the standpoint of improving crystal quality. Twin-free crystals have been grown reproducibly in the <lll>P direction under the following conditions; (1) using starting material which does not contain fine InP particles, (2) controlling the cone shape of the crystals such that the angle with the growth axis is less than 19.68°, (3) arranging the.hot zone to produce a temperature at the top surface of the B₂O₃ encapsulant layer below 550°C. It has been confirmed that electrical properties of nominally undoped crystals are dominated by the impurity, Si, and the concentration of Si in an LEC crystal corresponds to that of the starting material. The dislocation densities of undoped LEC InP crystals depend on thermal stresses during the growth process. This knowledge has led to the growth of dislocation-free crystals.     

Features of the exciton spectra of CdS(O) single crystals

The exciton cathodoluminescence spectra of CdS(O) single crystals are investigated depending on the depth (0.3?C125 ??m). It is found that the CdS(O) solid solution is stable in the bulk, where the crystal lattice provides the compensation of strains due to the isoelectronic impurity O_S. Near the surface (to 0.5 ??m), the CdS(O) solid solution can lose oxygen when forming CdO or SO₂. The stimulated radiation wavelength of the CdS(O) crystals depends on the O_S concentration in the bulk, which corresponds to the data of analyses.     

大直径高质量锑化铟单晶的生长研究

锑化铟单晶是制备3μm～5μm红外探测器的重要材料.为了适应红外焦平面探测器大规模化发展的趋势,我们开展了高质量3in锑化铟单晶的生长研究.本文解决了大直径锑化铟单晶生长的关键技术,讨论了3in锑化铟单晶生长过程中的多晶原料提纯问题,以及单晶电性能参数控制、位错密度控制和直径控制问题,并采用Czochraski法成功地在国内首次生长出直径为3in的锑化铟单晶.其中,直径大于3in的单晶长度超过100mm,单晶的位错密度小于100cm-2.试验结果表明:相对于其他半导体单晶生长位错密度沿晶棒增大的分布规律,我们得到的锑化铟单晶位错密度沿晶棒从头至尾递减,单晶尾部位错密度可小于50cm-2;同时单晶的电子迁移率、载流子浓度均满足制备高性能大规格红外焦平面探测器的要求.     

InSb quantum dot LEDs grown by molecular beam epitaxy for mid-infrared applications

We report the molecular beam epitaxial growth of InSb quantum dots (QD) inserted as sub-monolayers in an InAs matrix which exhibit intense mid-infrared photoluminescence up to room temperature. The InSb QD sheets were formed by briefly exposing the surface to an antimony flux (Sb₂) exploiting an As-Sb anion exchange reaction. Light emitting diodes were fabricated using 10 InSb QD sheets and were found to exhibit bright electroluminescence with a single peak at 3.8 μm at room temperature.     

基于PMN-PT单晶的双通道热释电红外气体探测器

锰离子掺杂铌镁酸铅-钛酸铅(Mn:Pb(Mg1/3Nb2/3)O3-PbTiO3,Mn:PMN-PT)弛豫铁电单晶在近、中红外波段具有较高的光透过率.通过在其表面上沉积具有宽光谱平坦吸收特性的红外吸收层,制备了热释电红外响应元.对该材料吸收红外辐射后产生的温度差以及热释电电流随频率的变化进行了模拟.讨论了电压模式热释电...     

100 mm直径低位错密度InSb单晶生长研究

InSb是一种重要的中波红外探测器材料。为了满足更大规模、更高质量红外焦平面探测器的发展要求,对100 mm直径低位错密度InSb单晶的生长进行了研究。通过改良生长方法、优化籽晶、改进缩颈工艺、优化热场,最终获得位错密度小于等于100 cm-2、直径大于等于100 mm的大尺寸低位错密度InSb晶体。晶体沿晶棒从头到尾部的位错密度分布均匀,可用率高,能够满足大规模高质量红外焦平面探测器的使用需求。