氮化铝一维纳米结构制备方法和物性研究的最新进展

全面总结了近年来氮化铝一维纳米结构的各种制备方法及物理性能等研究的最新进展,并提出了有待进一步深入研究的一些发展方向。     

蓝宝石衬底上原子级光滑AlN外延层的MOCVD生长

在蓝宝石衬底表面无氮化、低Ⅴ/Ⅲ比的情况下,采用1200℃的衬底温度、5kPa反应室气压,用MOCVD方法在蓝宝石衬底上生长出了表面原子级光滑的AlN外延层.原子力显微镜测试表明其平均粗糙度为0.44nm,X射线衍射(0002)回摆曲线FWHM为166".实验结果和分析表明,极性和气相反应是影响AlN表面形貌的主要原因.以原子级光滑的AlN为模板生长出了高质量的高Al组分的n型AlGaN,证实了AlN模板具有较好的质量.     

Comparative studies of normally-off Al0.26Ga0.74N/AlN/GaN/Si high electron mobility transistors with different gate structures

Systematic designs to achieve normally-off operation and improved device performance for Al_0.26Ga_0.74N/AlN/GaN high electron mobility transistors (HEMTs) grown on a Si substrate are investigated in this work. The step-by-step approach includes: (1) devising a thin AlGaN/AlN composite barrier, (2) introducing fluoride ions within the active region by using CF₄ plasma treatment, (3) growing the Al₂O₃ oxide passivation layers within gate-drain/source regions by using a cost-effective ozone water oxidization technique, and (4) integrating a metal-oxide-semiconductor gate (MOS-gate) design with high-k Al₂O₃ gate dielectric. Devices with four different evolutionary gate structures have been compared and studied. Variations of threshold voltage (V_th), Hooge coefficients (α_H), maximum drain-source current density (I_{DS, max}), maximum extrinsic transconductance (g_{m, max}), gate-voltage swing (GVS) linearity, two-terminal gate-drain breakdown/turn-on voltages (BV_GD/V_on), on/off current ratio (I_on/I_off), and high-temperature characteristics up to 450 K are also investigated.     

Fabrication of micro heaters on polycrystalline 3C-SiC suspended membranes for gas sensors and their characteristics

This paper describes the design, fabrication, and characteristics of micro heaters mad on AlN (0.1 μm)/3C-SiC (1 μm) suspended membranes using surface micromachining technology. 3C-SiC and AlN thin films, which have a large energy band gap and very low lattice mismatch, were used for high-temperature environments. A Pt thin film was used as micro heaters and temperature sensor materials. The resistance of the temperature detector (RTD) and the power consumption of the micro heater were measured and calculated. The heater is designed for an operating temperature up to about 800 °C and can be operated at about 500 °C with a power of 312 mW. The thermal coefficient of the resistance (TCR) of fabricated Pt RTD’s is 3174.64 ppm/°C. The thermal distribution measured by IR thermovision is uniform across the membrane surface.     

AlN插入层与AlGaN/GaN HEMT电流崩塌效应的关系

比较有无AlN插入层AlGaN/GaN HEMTs在直流偏置应力条件下的电流崩塌程度,研究AlN插入层对电流崩塌的影响.从测试结果看,无AlN插入层的AlGaN/GaN HEMTs有更显著的电流崩塌程度,表明AlN插入层对电流崩塌效应有显著的抑制作用.模拟的AlGaN/GaN能带结构表明,AlN插入层能显著提高AlGaN导带底能级,增加异质结的带隙差.带隙差的增加有利于减小电子遂穿几率,加强沟道二维电子气的量子限制,从而抑制电流崩塌效应.     

氮化铝陶瓷生产关键技术研究现状

氮化铝(AlN)陶瓷具有热导率高、热膨胀系数低、电阻率高等特性以及良好的力学性能,被认为是新一代高性能陶瓷基片和封装的首选材料。总结氮化铝陶瓷生产化的控制因素,分别从粉体的制备、防水化能力、成型过程、低温烧结以及应用等几个方面加以论述,并提出氮化铝陶瓷今后批量化生产过程中工艺技术的发展方向。     

AlN基板与金属化层界面的分析电镜研究

利用各种分析电镜观察了掺杂助烧剂和未掺杂助烧剂的ＡｌＮ陶瓷的微观结构特征，鉴别了ＡｌＮ中的第二相，研究了ＡｌＮ基板上薄膜（Ａｕ－Ｐｔ－Ｔｉ）和厚膜（Ｍｏ－Ｍｎ）金属化界面的结构。     

Tailored wafer holder for a reliable deposition of sputtered aluminium nitride thin films at low temperatures

Active actuated resonant micro-electro-mechanical-systems (MEMS) are used for sensing purpose like topography analysis and viscosity sensors. Those applications require straight beams and they rely on controlled film stress of the involved thin films, e.g. the active piezoelectric aluminium nitride (AlN) layer. The AlN consists of aluminium and nitrogen and is deposited with a reactive sputter process. The deposition process heats up the substrate and therefore the wafer bow of the substrate causes a variation of the thermal connection between wafer and sample holder. This goes along with undefined film stress of the AlN layer. In order to minimize the derivation of film stress, the reduction of substrate temperature and the enhancement of thermal connection between substrate and substrate holder is targeted. Therefore a novel clamped substrate holder is designed. High thermal connection to the ambient equipment, equal heat distribution and clamping of wafer stabilize the deposited AlN layer. By examining the layer stress and applying an acid structuring method, an improvement of deposited film is observed. A long term study with AlN deposition with thicknesses of 0.5 µm, 1.0 µm and 2.0 µm on silicon wafers was made to confirm the enhancement.     

Low energy electron excited nanoscale luminescence spectroscopy of erbium doped AIN

We have investigated the optical activity of Er³⁺ ions in AlN via depth-resolved, (5 nm to 250 nm), low energy electron-excited nanoscale (LEEN) luminescence spectroscopy and compared it with the luminescence of an Er-free AlN film. For the Er-free film, there was no emission in the IR from the AlN at any depth, and at higher energies we measured only a broad, weak feature between 1.7–3.25 eV along with an O defect related feature at 3.8 eV, which is significantly enhanced toward the surface. We found strong emission in the AlN:Er films from the first excited → ground state transition of Er³⁺ at 0.80 eV along with many other excited state transitions, although the features are broad compared to those of GaN:Er. The AlN:Er luminescence saturates near a concentration of 10²¹ cm⁻³, at which point we also observe enhanced O defect related luminescence uniformly distributed throughout the film. This finding suggests a role for O in activating the Er at low Er concentrations, while inhibiting the Er activity at high O concentrations.     

纳秒准分子激光合成制备TiN／AlN多层复合膜研究

采用纳秒准分子激光在单晶硅试样表面制备了调制周期为50nm、调制比为2的TiN／AlN多层复合膜,并研究了N2分压对多层膜微结构和硬度的影响。结果表明,在低N2分压下薄膜表面颗粒相对较小,颗粒之间的空隙也不明显;随着N2分压的升高,薄膜表面颗粒明显粗化,且直径变大高度增高,颗粒之间孔隙变大。X射线衍射（XRD）研究表明...