Y型量子线中电子弹道输运性质

对有限长 Y型量子线中的电子弹道输运性质进行了量子力学计算 .该有限长的量子结构分与两半无限长的量子通道相连 ,当施加一偏压时 ,量子通道分别可作为电子的发射极和收集极 .采用了转移矩阵方法和截断近似技术 .计算结果表明 ,当结构对于 x轴对称时 ,在入射电子的能量小于量子结构的第一个横向本征模时 ,电导存在着两个峰 ;当结构对于 x轴不对称时 ,电导则存在着三个峰 .进一步分析表明 ,这些峰来自于电子共振隧穿量子结构中的量子束缚态 .该结构对于经典粒子来说是非束缚体系 .当结构对于 x轴对称时 ,较高能级是双重简并的 ,而当结构对于 x轴不对称     

量子阱中电子隧穿逃逸时间的研究

用波包方法计算了电子从量子阱中的隧穿逃逸时间随外加偏压的变化，与实验结果符合良好，通常半经典近似模型与实验结果偏离较大，通过对两者的比较给出了改进的半经典模型，大大简化了隧穿逃逸时间的计算。     

模式耦合对量子线电子输运性质的影响

利用一般传输矩阵方法 (Transfer matrix method)和耦合模传输矩阵方法 (Coupledmode transfer matrix method) ,分别计算了几种处于弹道区的非均匀边界形状量子线的电导 ,研究量子线通道相邻分段区域电子传输模式之间的耦合对电导的影响。结果表明 ,这种耦合对空腔结构量子线电子输运性质有重要影响 ,是研究非均匀边界形状量子线电导必须考虑的关键因素。     

多量子阱系统结构变化对电子共振隧穿的影响

文中通过求解薛定谔方程得到由Ｎ个矩形势垒构成的量子系统的变换矩阵和电子透射系数的精确解，研究了多量子阱系统结构变化对电子共振隧穿的影响。     

小偏压下阱中阱结构的量子隧穿特性及其实现

共振隧穿是电子的隧穿概率在某一个能量值附近以尖锐的峰值形式出现的隧穿,是目前为止最有希望应用到实际电路和系统的量子器件之一,其特点是器件的响应速度非常快。本文用传递矩阵的方法分别计算了在外加偏压下,对称双势垒、三势垒应变量子阱结构的透射系数与入射电子能量和隧穿电流与偏置电压的关系,模拟了应变多量子阱结构的隧穿系数和I-V特性曲线。计算得到隧穿电流峰值位置与实验测试值符合得很好,对于设计共振隧穿二极管并为进一步实验提供理论指导具有重要的意义。     

纳米硅二极管的电输运特性

用ＰＥＣＶＤ法在Ｓｉ衬底上沉积了纳米硅（ｎｃ－Ｓｉ：Ｈ）薄膜，其室温暗电导可达１０＾３－１０＾－１Ω＾－１ｃｍ＾－１，高于本征单晶硅的电导，将其制成遂道二极管，其Ｉ－Ｖ曲线在７７Ｋ呈现出量子台阶，对这一新颖物理现象进行了定性解释。     

双量子阱结构中电子共振隧穿的相干模型

提出了一种新的计算双量子阱结构中电子共振隧穿时间的相干模型,理论计算与报道的实验结果基本一致.进一步的讨论表明,在有电子散射的情况下,随着势垒厚度的增加,对比度存在极大值,而与类Fabry-Perot模型的单调增加趋势明显不同.     

抛物形量子阱的共振隧穿

文中通过求解薛定谔方程得到抛物型形量子阱的变换矩阵与透射系数。利用这一结果计算透射系数可以达到任意高的精度，最后，讨论了结构变化对抛物型量子阱的共振隧穿的影响。     

量子效应器件正在崛起

本文介绍了量子效应器件的定义、分类、特点、工作原理、特性、制造方法和应用。还介绍了国内研制量子效应器件的动态和成果。     

自组装Si量子点阵中室温共振隧穿及微分负阻特性

报道了自组装Si量子点(Si-QDs)阵列在室温下的共振隧穿及其微分负阻特性.在等离子增强化学气相沉淀系统中,采用layer-by-layer的淀积技术和原位等离子体氧化方法制备了Al/SiO2/Si-QDs/SiO2/Substrate双势垒结构.通过原子力显微镜和透射电子显微镜检测,证实所获得的Si-QDs阵列中Si量子点平均尺寸为6nm,并具有较好的尺寸均匀性(小于10%).在对样品的室温I-V和C-V特性的测量中,直接观测到由于Si量子点中分立能级而引起的共振隧穿和充电效应:I-V特性表现出显著的"微分负阻特性(NDR)";而CV特性中也同样观测到位置相对应、结构相似的峰结构,从而证实了I-V和C-V特性中的峰结构都同样来源于电子与Si量子点阵列中分离能级之间的共振隧穿和充电过程.进一步研究发现,Si量子点阵列中共振隧穿和NDR特性所特有"扫描方向"和"速率"依赖性及其机制,与量子阱的情况有所不同.通过所建立的主方程数值模型,成功地解释并重复了Si量子点阵中共振隧穿所特有的输运特性.     

Importance of Backscattering Effects in Ballistic Quantum Transport in Mesoscopic Ring Structures

We have found that in the ballistic electron transport in a ring structure, the junction-backscattering contribution is critical for all the major features of the Aharonov-Bohm-type interference patterns. In particular, by considering the backscattering effect, we present new and clear interpretation about the physical origin of the secondary minima in the electrostatic Aharonov-Bohm effect and that of the h/2e oscillations when both the electric and magnetic potentials are present. We have devised a convenient scheme of expanding the conductance by the junction backscattering amplitude, which enables us to determine most important electron paths among infinitely many paths and to gain insight about their contributions to the interference patterns. Based on the scheme, we have identified various interesting interference phenomena in the ballistic ring structure and found that the backscattering effect plays a critical role in all of them.     

Ballistic Transport in InP-Based HEMTs

Ballistic transport has been of interest in semiconductor devices for quite some time, and its effect has been used to predict quite-different device performance. Here, we investigate the role of ballistic transport in a short-channel InGaAs/InAlAs HEMT through full-band cellular Monte Carlo simulations. We can examine the contrast in behavior between when scattering mechanisms are present and when they are turned off. When the scattering processes are completely removed, the output characteristics show a distinct change in behavior over all drain voltages. This result is in qualitative agreement with prior arguments, suggesting that triodelike behavior should be expected due to enhanced drain-induced barrier lowering. However, we find that explicit band-structure effects are observable in the output characteristics of the ballistic transistor. We also find that this distinctive behavior gradually disappears as scattering is turned on, particularly in the drain end of the device. We also develop a method of determining the probability that electrons pass through the gate region in a ballistic manner in the presence of realistic scattering. Even when the gate is only 10 nm long, we find that this probability is only on the order of 50% in these devices. We also examine the ballistic ratio in our device as a function of gate length.      

Entanglement-Assisted Capacity of Quantum Multiple-Access Channels

We find a regularized formula for the entanglement-assisted (EA) capacity region for quantum multiple-access channels (QMAC). We illustrate the capacity region calculation with the example of the collective phase-flip channel which admits a single-letter characterization. On the way, we provide a first-principles proof of the EA coding theorem based on a packing argument. We observe that the Holevo-Schumacher-Westmoreland theorem may be obtained from a modification of our EA protocol. We remark on the existence of a family hierarchy of protocols for multiparty scenarios with a single receiver, in analogy to the two-party case. In this way, we relate several previous results regarding QMACs.     

2D MXene Nanofilms with Tunable Gas Transport Channels

2D materials' membranes with well‐defined nanochannels are promising for precise molecular separation. Herein, the design and engineering of atomically thin 2D MXene flacks into nanofilms with a thickness of 20 nm for gas separation are reported. Well‐stacked pristine MXene nanofilms are proven to show outstanding molecular sieving property for H₂ preferential transport. Chemical tuning of the MXene nanochannels is also rationally designed for selective permeating CO₂. Borate and polyethylenimine (PEI) molecules are well interlocked into MXene layers, realizing the delicate regulation of stacking behaviors and interlayer spacing of MXene nanosheets. The MXene nanofilms with either H₂‐ or CO₂‐selective transport channels exhibit excellent gas separation performance beyond the limits for state‐of‐the‐art membranes. The mechanisms within these nanoconfined MXene layers are discussed, revealing the transformation from “diffusion‐controlled” to “solution‐controlled” channels after chemical tuning. This work of precisely tailoring the 2D nanostructure may inspire the exploring of nanofluidics in 2D confined space with applications in many other fields like catalysis and energy conversion processes.     

Quantum Transport Simulation of Experimentally Fabricated Nano-FinFET

We have utilized the contact-block-reduction (CBR) method, which we extended to allow a charge self-consistent scheme, to simulate experimentally fabricated 10-nm-FinFET device. The self-consistent CBR simulator has been modified to simulate devices with channels along arbitrary crystallographic orientation. A series of fully quantum-mechanical transport simulations has been performed. First, the fin extension length and doping profile have been calibrated to match the experimental data. The process control window for the threshold voltage as a function of fin extension has been extracted for the considered device. Then, a set of transfer characteristics and gate leakage currents have been calculated for different drain voltages. The simulation results have been found to be in good agreement with the experimental data in the subthreshold regime. The device turn-off and turn-on behavior has been examined for different fin widths: 12 (experimental), 10, 8, and 6 nm. Finally, the subthreshold slope degradation at high temperatures has been studied     

考虑源漏隧穿的DG MOSFET弹道输运及其模拟

在经典弹道输运模型中引入源漏隧穿 (S/ D tunneling) ,采用 WKB方法计算载流子源漏隧穿几率 ,对薄硅层(硅层厚度为 1nm) DG(dual gate) MOSFETs的器件特性进行了模拟 .模拟结果表明当沟道长度为 10 nm时 ,源漏隧穿电流在关态电流中占 2 5 % ,在开态电流中占 5 % .随着沟道长度进一步减小 ,源漏隧穿比例进一步增大 .因此 ,模拟必须包括源漏隧穿 .     

考虑源漏隧穿的DG MOSFET弹道输运及其模拟

在经典弹道输运模型中引入源漏隧穿(S/D tunneling),采用WKB方法计算载流子源漏隧穿几率,对薄硅层(硅层厚度为1nm)DG(dual gate)MOSFETs的器件特性进行了模拟.模拟结果表明当沟道长度为10nm时,源漏隧穿电流在关态电流中占25%,在开态电流中占5%.随着沟道长度进一步减小,源漏隧穿比例进一步增大.因此,模拟必须包括源漏隧穿.