p型GaN上Pd/NiO/Al/Ni反射电极欧姆接触的热稳定性研究

研究了p型GaN上Pd/NiO/Al/Ni反射电极欧姆接触的比接触电阻率、热稳定性,以及光学反射率。与传统Pd/Al/Ni电极相比,Pd/NiO/Al/Ni电极的欧姆接触在氮气环境中经300℃下热处理10min后,仍保持低比接触电阻率(小于5×10-4Ω·cm2)和高反射率(大于80%@365nm)。研究获得的优化Pd/NiO层厚度为1nm/2nm,此时的Pd/NiO/Al/Ni反射电极既能形成良好的欧姆接触,拥有低比接触电阻率,又能减少对紫外光的吸收,保持高反射率。研究表明适当的NiO层厚度能够有效地防止热处理过程中上层Al金属向p-GaN表面层的渗入,对于制备高质量的Al基反射电极至关重要。     

自组装NiO/还原氧化石墨烯复合材料及其超级电容性能研究

通过水热法制备得到α-Ni(OH)₂,在甲酰胺溶剂中,通过机械振荡结合超声对其进行剥离,得到厚度约为1.1 nm的Ni(OH)₂纳米片,与氧化石墨烯(GO)悬浮液混合后,静电自组装得到Ni(OH)₂/GO,经高温热处理获得NiO/还原氧化石墨烯(rGO)复合材料。同时研究了NiO/rGO的结构、形貌及其用作超级电容器电极材料的电化学性能。形貌表征显示NiO/rGO呈层-层形貌,N₂吸-脱附实验表明复合材料存在介孔结构。在KOH电解液中,1 A/g电流密度下NiO/rGO的比容量为1564 F/g,远高于初始Ni(OH)₂和单纯的NiO;组装的NiO/rGO//石墨烯水凝胶(GH)非对称超级电容器(ASC)器件,充放电电位窗口为0～1.6 V,10 A/g电流密度下经1000次充放电循环的比容量保持率达84.2%。     

冷冻煅烧法制备NiO/Ni复合材料及电容性能研究

首次采用冷冻煅烧法制备NiO/Ni纳米复合材料,重点考察不同冷冻温度对该复合材料的结构形貌及电容性能的影响。结果表明:随着冷冻温度的降低,结晶过冷度增大,材料的粒径不断减小并且趋于均匀化,比表面积单调增大。当冷冻温度为-20℃时,材料平均粒径为20~50 nm,比表面积达到337.6 m^2/g。同时,纳米Ni单质的引入也增强了材料的导电性能,当电流密度为1 A/g时,其比电容达到820 F/g,所制得NiO/Ni纳米复合材料具有优异的电化学性能。该方法大大降低了材料制备的能耗,为NiO/Ni纳米复合材料的制备方法提供新的思路。     

Ni层厚度对p-GaN/Ni/Au欧姆接触特性的影响

对p-GaN/Ni/Au欧姆接触特性与Ni金属层厚度之间的相关性进行了对比实验研究,利用XRD衍射结果与表面金相显微分析手段对Ni/Au双层金属电极在合金退火过程中的行为特性进行了细致探讨。分析结果表明:在Ni/Au电极结构中,由双层互扩散机制与NiO氧化反应机理决定,Ni层与Au层之间的厚度比率对p型GaN欧姆接触特性的优劣有重要影响,在Ni、Au层厚度相当时可获得最佳的p型欧姆接触。     

Si/Co/GaAs体系中界面反应的竞争机制

本文采用AES、XRD和TEM等技术对Si/Co/GaAs三层结构的界面反应作了较详细的研究。结果表明:Si/Co与Co/GaAs两界面的反应具有一定的相似性,即当退火温度低于300℃时,两界面都保持完整;当退火温度高于400℃时,两界面都发生了化学反应,并形成相应的化合相。由于两界面的初始反应条件相近,因而界面反应存在着竞争机制,通过进一步的实验,结果表明;Si/Co界面的反应速度要比Co/GaAs的快,从而为在GaAs衬底上形成CoSi_2/GaAs金半接触提供了有利条件。     

实验参数对激光气相法制备Fe/C、Fe/N超细粒子性能的影响

采用激光气相法，研究了实验参数对实验过程及Fe／C、Fe／N超细粒子性能的影响，并用EDTA化学分析法、透射电镜、电子衍射及振动样品磁强计等手段对超细粒子的化学成份、粒径、形貌、结构及磁性等性能进行了分析。     

NiO/SiC异质结的光电特性（英文）

NiO是一种天然p型直接带隙半导体材料,首次采用磁控溅射的方法在n型4H-SiC(0001)衬底上淀积NiO薄膜,制作p-NiO/n-4H-SiC异质结。研究了氧气和氩气体积流量对NiO薄膜特性的影响,并研究了NiO/SiC异质结的光电特性。结果表明:所制备的NiO薄膜为多晶结构,当氧气和氩气体积流量均为30 cm~3/min时,NiO薄膜出现[200]晶向的择优生长,呈现p型导电,薄膜平整致密,粒径约为15 nm。采用Ni作为金属电极,J-V测试结果表明异质结具有较好的整流特性,开启电压约为1.4 V,在13.5 mW的紫外灯照射下,异质结出现了光响应,开路电压Voc约为30 mV,光电流密度Jph为0.89 mA/cm~2。     

金属氧化物改性炭电极及EDLC性能研究

将市售活性炭用Ni(NO3)2及Co(NO3)2溶液浸渍后进行高温热解处理。采用BET、循环伏安、恒流充放电等测试手段,研究改性活性炭电极构成的双电层电容器(EDLC)性能。结果表明,由Ni(NO3)2及Co(NO3)2热解产生的NiO、CoO有显著的准电容效应,与活性炭原有的双电层电容构成了复合电容,因而改性炭的电容量有明显提高,质量比电容分别高达246.1,198.8 F/g,比原样炭的130.1 F/g分别提高了89.2%、52.8%。     

激光熔覆镍基纳米WC/Co复合涂层的断裂韧性Kc的研究

对45钢表面激光熔覆Ni基纳米WC/Co复合涂层的断裂韧性Kc进行了研究。结果表明:激光熔覆Ni基纳米复合涂层的Kc≥18.0MN.m-3/2,而喷焊Ni基WC/Co复合涂层的Kc平均值为8.1 MN.m-3/2(最低值为4.4 MN.m-3/2)。分析认为:在本研究条件下,激光熔覆Ni基纳米WC/Co复合涂层中形成的呈三维网络结构分布的碳化物相及呈弥散分布的超细碳化物相的综合增强作用是该涂层断裂韧性Kc比常规喷焊同样材料(非纳米)涂层的Kc明显提高的主要原因。     

热处理气氛及掺钴对NiO电极赝电容器性能的影响

在讨论赝电容形成机理的基础上,应用电化学阴极沉积法在Ni基片上制得Ni(OH)2膜,经热处理得到NiO膜。研究发现,Ni(OH)2在空气中热处理所得NiO在KOH水溶液中能形成赝电容,但在N2气氛中热处理所得的NiO在KOH水溶液中未能形成赝电容;钴掺入NiO使比电容量显著增大。     

Application of polyimide to bending-mode microactuators with Ni/Fe and Fe/Pt magnet

Out-of-plane polyimide (PI) electromagnetic microactuators with different geometries are designed, fabricated and tested. Fabrication of the electromagnetic microactuators consists of 10 μm thick Ni/Fe (80/20) permalloy deposition on PI diaphragm by electroplating process, electroplating of copper planar coil with 10 μm thick, bulk micromachining, and excimer laser selective ablation. They are fabricated by a novel concept to avoid the etching selectivity and residual stress problems during wafer etching. A simulation model is created by ANSYS software to analyze the microactuators. The external magnetic field intensity (H_ext) generated by the planar coil is simulated by this software. Besides, to provide bi-directional and large deflection angles of the microactuators, hard magnet Fe/Pt is deposited at low temperature of 300 °C by sputtering onto the PI diaphragm to produce a perpendicular magnetic anisotropic field. This magnetic field can enhance the interaction with H_ext to induce attractive and repulsive bi-directional force to provide a larger displacement. The results of the magnetic microactuators with and without hard magnetic are compared and discussed, respectively. The preliminary result reveals that the electromagnetic microactuators with hard magnet exhibit a greater deflection angle than that without one.     

激光热解法制备铁系超微粉

以10.6灿mCW CO_2激光连续流动体系制备超微Fe粉和Fe/C粉,考察了过程参数对粉体性质的影响。     

Growth of Textured Au–Fe/Fe Hybrid Nanocrystals on Oxidized Silicon Surface

Semiconductors - We present in this report the route to produce highly-textured Au3Fe(111)/Fe(110) hybrid nanocrystals on an amorphous surface of SiO2/Si by molecular beam epitaxy. By controlling...     

C/FePt/Fe纳米薄膜的微结构和磁特性

利用超高真空磁控溅射方法制备了一系列不同C层厚度的C/FePt/Fe纳米薄膜,然后进行原位高温退火。应用X射线衍射仪(XRD)分析了样品的晶体结构,利用扫描探针显微镜(SPM)观测了表面形貌和磁畴结构,通过振动样品磁强计(VSM)测量了磁性。结果表明,薄膜的微结构和磁特性随C覆盖层厚度的变化有着非常显著的变化。C的加入使样品表面更加光滑,使10 nm厚的C覆盖层样品获得了0.3 nm的粗糙度和3.8 nm的颗粒尺寸。C覆盖层减弱了磁性颗粒间的磁偶极作用,同时减弱了磁性颗粒间的交换耦合作用,提高了L10织构的有序化程度,进而增大了样品的矫顽力,矫顽力达到了987 kA/m。     

Epitaxially regrown GaAs/AlGaAs laser mesas with semi-insulating GaInP:Fe and GaAs:Fe

Selective regrowth of semi-insulating iron-doped Ga_0.51In_0.49P (SI-GaInP:Fe) and SI-GaAs:Fe around GaAs/AlGaAs mesas by hydride vapor phase epitaxy (HVPE) has been achieved. A HCl based in-situ cleaning procedure has been used to remove aluminum oxide from the etched walls of the mesas. Regrowth conducted without proper cleaning results in an irregular interface with voids. Regrowth morphology aspects are also presented. Our cleaning and regrowth methods have been used for fabricating GaAs/AlGaAs buried heterostructure in-plane lasers and vertical-cavity surface-emitting lasers.     

Nanoscintillator-Mediated X-Ray-Triggered Boosting Transformation of Fe3+ into Fe2+ for Enhancing Tumor Ferroptosis/Immunotherapy

Ferroptosis therapy induced by iron-catalyzed Fenton reaction has offered enormous opportunities for tumor therapy. Unfortunately, high catalytic activity ferrous (Fe²⁺)-based therapeutic agent has remained challenging due to the instability of Fe²⁺. Herein, an X-ray-activated Fe²⁺ supply platform, termed “PFCN”, containing the core of CaWO₄ nanoscintillator to emit ultraviolet (UV) light and Fe₃O₄ decorated on the surface to deliver excessive Fe²⁺ is proposed. Under X-ray excitation, the UV light emitted by CaWO₄ can catalyze ferric (Fe³⁺) to generate Fe²⁺, which further cascades the Fenton reaction to induce highly toxic hydroxyl radicals generation. More importantly, immunogenic cell death-associated immunotherapy is simultaneously triggered during this process. Experiments conducted in vitro and in vivo revealed that X-ray-triggered PFCN shows superior tumor therapeutic efficacy, contributing i) enhanced radiotherapy; ii) X-ray-activated ferroptosis therapy; and iii) ferroptosis/radiotherapy-induced immunotherapy. Besides, PFCN can be utilized as an MR/CT dual-mode imaging contrast agent for tumor diagnosis and treatment monitoring. The study provides a novel example of an X-ray-activated ferrous-regeneration platform for imaging-guided augmenting tumor ferroptosis/immunotherapy     

Giant and Nonvolatile Control of Exchange Bias in Fe3GeTe2/Irradiated Fe3GeTe2/MgO Heterostructure Through Ultralow Voltage

The discovery of van der Waals magnets has provided a new platform for the electrical control of magnetism. Recent experiments have demonstrated that the magnetic properties of van der Waals magnets can be tuned by various gate modulations, although most of them are volatile and require gate voltages no lower than several volts. Here, the realization of nonvolatile control of exchange bias and coercive fields in Fe₃GeTe₂/MgO heterostructures, and the gate voltage is as low as tens of mV which is two orders of magnitude smaller than those in previous experiments is presented. The discovery of an ionic-irradiated phase formed in Fe₃GeTe₂ by MgO sputtering revealed that an exchange bias effect can be obtained in this heterostructure and tuned from ≈700 to 0 Oe through voltages ranging from 5 to 20 mV. Owing to the high stability of oxidized Fe₃GeTe₂, the voltage-driven oxygen incorporated into Fe₃GeTe₂ from the irradiated phase induces a nonvolatile magnetism modulation that can be retained after turning off the gate voltage. These findings demonstrate a methodology to modulate the magnetism of van der Waals magnets, opening new opportunities to fabricate all-solid, long-retention, and low-dissipation nano-electronic devices using van der Waals materials.     

Fe:ZnS/ZnSe中红外固体激光器研究进展

高性能中红外激光在军事对抗、生物安全、环境科学等领域有重要的应用价值。Fe:ZnS/ZnSe具有长输出波长、宽吸收带和发射带的特点,是实现高性能、宽调谐3μm~5μm激光输出的最有效激光介质。介绍了Fe:ZnS/ZnSe的光谱和热动力学特性,评述了Fe:ZnS/ZnSe在低温和常温下激光输出性能方面的最新进展,分析了Fe:ZnS/ZnSe激光器在功率、能量提升以及室温运转方面面临的科学挑战。     

GHz bandstop microstrip filter using patterned Ni/sub 78/Fe/sub 22/ ferromagnetic film

A series of microstrips with patterned Ni/sub 78/Fe/sub 22/ ferromagnetic cores have been investigated for RF applications. The devices have been integrated onto a silicon substrate by using a fully IC-compatible process. The Ni/sub 78/Fe/sub 22/ films were deposited by electroplating onto Si at room temperature and were structured into rectangular prisms with large aspect ratios, i.e., 10:1 and 40:1. Measurements have been performed using a network analyzer. Voltage attenuation of 19 dB/cm has been obtained at 3.9 GHz on a 2-mm-long strip line. The propagating wavelength is reduced by 60% compared to a control device without ferromagnetic core.