排序方式: 共有19条查询结果,搜索用时 546 毫秒
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面向国家"战略性先进电子材料"的发展目标,以国家重大战略需求,如全球气候观测、农林普查、国土资源探测、环境监测、深空探测和天文观测等领域的技术发展中面临的光探测器瓶颈问题为突破口,瞄准半导体材料及其光探测器正在朝全光谱覆盖、大面阵、高灵敏等方向快速发展的国际态势,开展低维半导体异质结构材料与光电器件研究,发展该体系材料人工设计精细调控的关键技术,推动多波段多种类型的光电探测器技术进步,促进我国经济、社会、国家安全及科学技术的发展. 相似文献
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A full-scale, self-consistent, non-linear, large-signal model of double-drift hetero-structure IMPATT diode with general doping profile is derived. This newly developed model, for the first time, has been used to analyze the large-signal characteristics of hexagonal SiC-based double-drift IMPATT diode. Considering the fabrication feasibility, the authors have studied the large-signal characteristics of Si/SiC-based hetero-structure devices. Under small-voltage modulation (~ 2%, i.e. small-signal conditions) results are in good agreement with calculations done using a linearised small-signal model. The large-signal values of the diode's negative conductance (5 × 106S/m2), susceptance (10.4 × 107 S/m2}), average breakdown voltage (207.6 V), and power generating efficiency (15%, RF power: 25.0 W at 94 GHz) are obtained as a function of oscillation amplitude (50% of DC breakdown voltage) for a fixed average current density. The large-signal calculations exhibit power and efficiency saturation for large-signal (> 50%) voltage modulation and thereafter decrease gradually with further increasing voltage-modulation. This generalized large-signal formulation is applicable for all types of IMPATT structures with distributed and narrow avalanche zones. The simulator is made more realistic by incorporating the space-charge effects, realistic field and temperature dependent material parameters in Si and SiC. The electric field snap-shots and the large-signal impedance and admittance of the diode with current excitation are expressed in closed loop form. This study will act as a guide for researchers to fabricate a high-power Si/SiC-based IMPATT for possible application in high-power MM-wave communication systems. 相似文献
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The authors have reported their recent progress in the research field of ZnO materials as well as the corresponding global advance. Recent results regarding(1) the development of high-quality epitaxy techniques,(2) the defect physics and the Te/N co-doping mechanism for p-type conduction, and(3) the design, realization, and properties of the ZnMgO/ZnO hetero-structures have been shown and discussed. A complete technology of the growth of high-quality ZnO epi-films and nano-crystals has been developed. The co-doping of N plus an iso-valent element to oxygen has been found to be the most hopeful path to overcome the notorious p-type hurdle. High mobility electrons have been observed in low-dimensional structures utilizing the polarization of ZnMgO and ZnO. Very different properties as well as new physics of the electrons in 2DEG and 3DES have been found as compared to the electrons in the bulk. 相似文献
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研究了ZnO薄膜中应力对发光的影响.实验样品为ZnO体单晶、在Si基片上直接生长的ZnO薄膜以及通过SiC过渡层在Si基片上生长的ZnO薄膜.测量了这三种样品的X射线衍射图形、喇曼光谱和光致发光光谱.由X射线衍射图形可以看出,由于SiC过渡层缓解了ZnO与Si之间的晶格失配,使得通过SiC过渡层在Si上生长的ZnO薄膜的结晶质量好于直接在Si上生长的ZnO薄膜的质量.进一步通过喇曼谱测量发现,与ZnO体单晶相比,直接在Si上生长的ZnO薄膜的E2(high)峰红移1.9cm-1,根据喇曼谱峰位移与应力的关系可以推出薄膜中存在0.4GPa的张应力;而通过SiC过渡层在Si上生长的ZnO薄膜的E2(high)峰红移0.9cm-1,对应着0.2GPa的张应力.对照X射线衍射图形的结果可以看出,薄膜中张应力的大小与薄膜的结晶质量密切相关,表明张应力来源于外延层和基片间的晶格失配,晶格失配越大,外延层中产生的张应力越大.有无SiC过渡层的两种薄膜样品的PL光谱中都存在紫外和绿光两种谱带,随样品热处理时氧气分压增加,两种样品都出现绿光增强的相似的变化规律,但有SiC过渡层的样品的变化幅度较小.这一结果说明,绿色发光中心与薄膜的质量,也就是与薄膜中存在的张应力大小有关.在以往研究中得出的非故意掺杂ZnO薄膜的绿色发光中心来源于氧反位缺陷(Ozn),文中研究的结果正好可以解释氧反位缺陷形成的原因.由于薄膜中存在张应力,使得样品的能量升高,其结果必然会产生缺陷来释放张应力,以便降低系统能量.而氧离子半径大于锌离子半径,氧替位锌有利于释放张应力,也就是说,在存在张应力的情况下,Ozn的形成能降低.这一结果进一步证明Si上生长的ZnO薄膜中的绿色发光中心与氧反位缺陷有关. 相似文献
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采用射频磁控溅射法制备了NbN,AlN单层膜及不同调制周期的AlN/NbN纳米结构多层膜,采用X射线衍射仪、小角度X射线反射仪和高分辨透射电子显微镜等对薄膜进行了表征.结果表明:单层膜AlN为六方结构,NbN为面心立方结构;AlN/NbN多层膜中AlN为六方结构,NbN为面心立方结构,界面处呈共格状态,其共格关系为c-NbN(111)面平行于h-AlN(0002)面,晶格错配度为013%.热力学计算表明:AlN/NbN多层膜中不论AlN层与NbN层的厚度如何,AlN层均不会形成亚稳的立方AlN,而是形成
关键词:
AlN/NbN纳米结构多层膜
共格外延生长
异结构 相似文献