共查询到19条相似文献,搜索用时 46 毫秒
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在很宽的温度范围(500—20K)研究了本征和不同掺磷浓度的纳米硅薄膜的电输运现象.发现 原先的异质结量子点隧穿(HQD)模型能很好地解释薄膜在高温下(500—200K)的电导曲线,但 明显偏离低温下的实验值.低温电导(100—20K)具有单一的激活能W,并与kBT值 大小相当(W~1—3kBT),呈现出Hopping电导的特征.对HQD模型做了修正,认为 纳米硅同时存在两种输运机制:热激发辅助的电子隧穿和费米能级附近定域态之间的Hoppin g电导.高温时(T
关键词:
纳米硅薄膜
低温电导
电输运 相似文献
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现代科学技术的发展、自动化程度的提高、计算机应用的普及,需要越来越多的高速大规模、超大规模集成电路.金属/氧化物/半导体场效应晶体管(MOSFET) 由于其工艺简单、产额高、功耗低、抗干扰能力强、输入阻抗高、易于大规模集成,在大规模集成电路领域内很受人们青睐.尤其是互补型金属/氧化物/半导体场效应晶体管(CMOS)电路,可在单电流下工作,且工作电压范围广、噪声容限大、集成度高.几乎有取代双极型晶体管集成电路的趋势.然而,CMOS电路的速度因受ρ沟MOS中空穴迁移率的限制,不如双极型器件的快,使它的应用受到一定的限制.如能提高它的工作速度,则可使MOS电路具有更强的生命力. 相似文献
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利用散射矩阵方法,比较了被一维凸形量子点、凹形量子点调制的量子线中膨胀模的声子输运和热导性质. 研究结果表明: 声子的输运概率与热导受制于量子点几何结构,具有凸形量子点结构的量子线中声子输运概率与热导KCV大于具有凹形量子点结构的量子线中声子输运概率与热导KCC. 两者热导之比KCV/KCC依赖于一维量子点的具体结构,且随着温度及主量子线与量子点横截面的边长差ΔSL的增加而增加. 两种具有不同散射结构的一维量子线中热输运性质的区别在于凸形量子点结构中膨胀模数量总是大于凹形量子点结构中膨胀模数量的缘故.
关键词:
声学声子输运
热导
量子结构 相似文献
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文章讨论了纳米器件发展方向和近期的研究成果,指出是子效应和纳米结构是将来的纳米器件的两大基础,以碳纳米管和各种电极组成的纳米结构为代表,论述了不同的量子效应及其在纳米器件中的可能应用。 相似文献
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纳米硅薄膜的量子特征及其应用前景 总被引:3,自引:0,他引:3
文章通过对纳米硅薄膜结构组分的研究,从实验和理论上共同探讨了其低维量子特征,并由此提出其电输运机制及其可见发光机理。最后,综合纳米硅薄膜的各种新颖物性,展望了其在纳米电子学和MEMS(微机电系统)领域内的应用前景。 相似文献
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A. Gunther M. Khoury S. Mili
i D. Vasileska T. Thornton S. M. Goodnick 《Superlattices and Microstructures》2000,27(5-6)
We report on the transport properties of novel Si quantum dot structures with controllable electron number through both top and side gates. Quantum dots were fabricated by a split-gate technique within a standard MOSFET process. Four-terminal dc electrical measurements were performed at 4.2 K in a liquid helium cryostat. Strong oscillations in the conductance through the dot are observed as a function of both the top gate bias and of the plunger bias. An overall monotonic and quasi-periodic movement of the peak conductance is observed which is believed to be associated with the bare level structure of the electronic states in the dot coupled with the Coulomb charging energy. Crossing behavior is observed as well, suggestive of either many-body effects or symmetry breaking of the dot states by the applied bias. 相似文献
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Coulomb blockade and hopping transport behaviors of donor-induced quantum dots in junctionless transistors 下载免费PDF全文
The ionized dopants, working as quantum dots in silicon nanowires, exhibit potential advantages for the development of atomic-scale transistors. We investigate single electron tunneling through a phosphorus dopant induced quantum dots array in heavily n-doped junctionless nanowire transistors. Several subpeaks splittings in current oscillations are clearly observed due to the coupling of the quantum dots at the temperature of 6 K. The transport behaviors change from resonance tunneling to hoping conduction with increased temperature. The charging energy of the phosphorus donors is approximately 12.8 meV. This work helps clear the basic mechanism of electron transport through donor-induced quantum dots and electron transport properties in the heavily doped nanowire through dopant engineering. 相似文献
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The ground state binding energy and the average interparticle distances for a hydrogenic impurity in double quantum dots with Gaussian confinement potential are studied by the variational method. The probability density of the electron is calculated, too. The dependence of the binding energy on the impurity position is investigated for GaAs quantum dots. The result shows that the binding energy has a minimum as a function of the distance between the two quantum dots when the impurity is located at the center of one quantum dot or at the center of the edge of one quantum dot. When the impurity is located at the center of the two dots, the binding energy decreases monotonically. 相似文献
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M. El Assaid M’hamed El Aydi M. El Feddi Françis Dujardin 《Central European Journal of Physics》2008,6(1):97-104
The problem of a shallow donor impurity located at the centre of a symmetrical paraboloidal quantum dot (SPQD) is solved exactly. The Schrödinger equation is separated in the paraboloidal coordinate system. Three different cases are discussed for the radial-like equations. For a bound donor, the energy is negative and the solutions are described by Whittaker functions. For a non-bound donor, the energy is positive and the solutions become coulomb wave functions. In the last case, the energy is equal to zero and the solutions reduce to Bessel functions. Using the boundary conditions at the dot surfaces, the variations of the donor kinetic and potential energies versus the size of the dot are obtained. The problem of a shallow donor impurity in a Hemiparaboloidal Quantum dot (HPQD) is also studied. It is shown that the wave functions of a HPQD are specific linear combinations of those of a SPQD. 相似文献
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We study the thermoelectric effect in a small quantum dot with a magnetic impurity in the Coulomb blockade regime.The electrical conductance,thermal conductance,thermopower,and the thermoelectrical figure of merit(FOM)are calculated by using Green’s function method.It is found that the peaks in the electrical conductance are split by the exchange coupling between the electron entering into the dot and the magnetic impurity inside the dot,accompanied by the decrease in the height of peaks.As a result,the resonances in the thermoelectric quantities,such as the thermal conductance,thermopower,and the FOM,are all split,opening some effective new working regions.Despite of the significant reduction in the height of the electrical conductance peaks induced by the exchange coupling,the values of the FOM and the thermopower can be as large as those in the case of zero exchange coupling.We also find that the thermoelectric efficiency,characterized by the magnitude of the FOM,can be enhanced by adjusting the left–right asymmetry of the electrode–dot coupling or by optimizing the system’s temperature. 相似文献
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We present effective mass, single-particle calculations of the electronic structure of n- and p-type silicon quantum dots. The structures investigated approximate silicon quantum dots fabricated on 〈 001〉-oriented SIMOX wafers. The effects of possible built-in strain are investigated in the framework of deformation potential induced splitting of the six degenerate conduction band valleys and the splitting of the degeneracy at the top of the bulk valence band. We present the energy levels and their degeneracies as functions of the dimensions of simple tetragonal model quantum dots. Our results are relevant for silicon quantum dots that are sufficiently small such as to lead to a predominance of the confinement energy over the Coulomb energy. 相似文献
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The emission of silicon quantum dots is weak when their surface is passivated well. Oxygen or nitrogen on the surface of silicon quantum dots can break the passivation to form localized electronic states in the band gap to generate active centers where stronger emission occurs. From this point of view, we can build up radiative matter for emission. Emissions of various wavelengths can be obtained by controlling the surface bonds of silicon quantum dots. Our experimental results demonstrate that annealing is important in the treatment of the activation, and stimulated emissions at about 600 and 700 nm take place on active silicon quantum dots. 相似文献
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以等离子增强化学气相沉积法制备的石墨烯作为导电沟道材料,将其与无机CsPbI_3钙钛矿量子点结合,设计并制备了石墨烯-钙钛矿量子点场效应晶体管光电探测器.研究和分析了石墨烯作为场效应晶体管的电学特性及其与钙钛矿量子点结合作为光电探测器的光电特性.结果表明,石墨烯在场效应晶体管中表现出良好的电学性质,其与钙钛矿量子点的结合对波长为400 nm的光辐射具有明显的光响应,在光强为12μW时器件光生电流最大为64μA,响应率达6.4 A·W~(-1),对应的光电导增益和探测率分别为3.7×10~4,6×10~7Jones(1 Jones=1 cm·Hz~(1/2)·W~(-1)). 相似文献
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The binding energy of a hydrogenic impurity in self-assembled double quantum dots is calculated via the finite-difference method. The variation in binding energy with donor position, structure parameters and external magnetic field is studied in detail. The results found are: (i) the binding energy has a complex behaviour due to coupling between the two dots; (ii) the binding energy is much larger when the donor is placed in the centre of one dot than in other positions; and (iii) the external magnetic field has different effects on the binding energy for different quantum-dot sizes or lateral confinements. 相似文献