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.     

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C-V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.     

硅基隧穿二极管

隧穿二极管是一种很有前途的基于带隙工程的异质结构量子器件,其电流电压(I-V)曲线中所呈现的微分负阻特性能够用于开发多种不同的电路功能。在最近的研究中,空穴型双势垒单势阱共振隧穿二极管得到了实现,为Si1-xGex/Si异质结隧穿二极管器件的改进和电路应用打下了良好的基础。     

耦合双量子点中基态电子的隧穿特性

介绍了以Si/SiO2系统构成的量子异或门的工作原理,研究了耦合不对称双量子点所构成的量子比特的电子隧穿特性.研究结果表明,通过栅压可很好地实现控制电子在两个量子点间共振隧穿,其隧穿时间随势垒厚度和量子点尺寸结构参数发生显著的变化.目前模拟的特征变化曲线表明,可获得实验上理想的隧穿时间(工作频率)和相应的栅压(工作电压).     

耦合双量子点中基态电子的隧穿特性

介绍了以Si/SiO2系统构成的量子异或门的工作原理,研究了耦合不对称双量子点所构成的量子比特的电子隧穿特性.研究结果表明,通过栅压可很好地实现控制电子在两个量子点间共振隧穿,其隧穿时间随势垒厚度和量子点尺寸结构参数发生显著的变化.目前模拟的特征变化曲线表明,可获得实验上理想的隧穿时间(工作频率)和相应的栅压(工作电压).     

三稳态共振隧穿器件的研制

在I-V特性曲线上具有双微分负阻的三稳态共振隧穿器件,室温下可以达到较高的电流峰谷比5.2∶1。器件采用两个隧穿二极管背靠背串联的结构,能更大程度提高集成度,可以在多值逻辑或其他有关降低电路复杂性方面获得较为广泛的应用。     

室温下Si/Si1-xGex共振隧穿二极管的数值模拟

采用量子水动力学(QHD)模型模拟了35nm Si/Si1-xGex空穴型共振隧穿二极管(RTD)在室温下的I-V特性.模拟过程中,引入second upwind,Schafetter-Gummel(SG)和二阶中心差分法相结合的离散方法对方程组进行离散,保证了结果的收敛性.还模拟了不同的器件结构,对结果的分析表明器件的势垒厚度和载流子有效质量都会对RTD的负阻效应产生影响.在室温下(T=293K),当x=0.23时,模拟结果的峰谷电流比为1.14,与实验结果相吻合.     

室温下Si/Si1-xGex共振隧穿二极管的数值模拟

采用量子水动力学(QHD)模型模拟了35nm Si/Si1-xGex空穴型共振隧穿二极管(RTD)在室温下的I-V特性.模拟过程中,引入second upwind,Schafetter-Gummel(SG)和二阶中心差分法相结合的离散方法对方程组进行离散,保证了结果的收敛性.还模拟了不同的器件结构,对结果的分析表明器件的势垒厚度和载流子有效质量都会对RTD的负阻效应产生影响.在室温下(T=293K),当x=0.23时,模拟结果的峰谷电流比为1.14,与实验结果相吻合.     

SiO2膜的薄层化对自组织生长Si纳米量子点发光特性的影响

采用低压化学气相沉积方法,依靠纯SiH4气体的热分解反应,在SiO2表面上自组织生长了Si纳米量子点.实验研究了SiO2膜的薄层化对Si纳米量子点光致发光特性的影响.结果表明,当SiO2膜厚度减薄至6nm以下时,Si纳米量子点中的光生载流子会量子隧穿超薄SiO2层,并逃逸到单晶Si衬底中去,从而减少了光生载流子通过SiO2/Si纳米量子点界面区域内发光中心的辐射复合效率,致使光致发光强度明显减弱.测试温度的变化对Si纳米量子点光致发光特性的影响,则源自于光生载流子通过SiO2/Si纳米量子点界面区域附近非发光中心的非辐射复合所产生的贡献.     

SiO2膜的薄层化对自组织生长Si纳米量子点发光特性的影响

采用低压化学气相沉积方法,依靠纯SiH4气体的热分解反应,在SiO2表面上自组织生长了Si纳米量子点.实验研究了SiO2膜的薄层化对Si纳米量子点光致发光特性的影响.结果表明,当SiO2膜厚度减薄至6nm以下时,Si纳米量子点中的光生载流子会量子隧穿超薄SiO2层,并逃逸到单晶Si衬底中去,从而减少了光生载流子通过SiO2/Si纳米量子点界面区域内发光中心的辐射复合效率,致使光致发光强度明显减弱.测试温度的变化对Si纳米量子点光致发光特性的影响,则源自于光生载流子通过SiO2/Si纳米量子点界面区域附近非发光中心的非辐射复合所产生的贡献.     

A double-barrier-emitter triangular-barrier optoelectronic switch

In this study, a triangular-barrier and a double-barrier structure are combined to form a double-barrier-emitter triangular-barrier optoelectronic switch (DTOS). In the structure center of the triangular barrier, a p-type delta-doped quantum well is inserted to enhance the hole confinement. Owing to the resonant tunneling through the double-barrier structure and avalanche multiplication in the reverse-biased junction, N-shaped and S-shaped negative-differential-resistance (NDR) phenomena occur in the current-voltage (I--V) characteristics under normal and reverse operation modes, respectively. The NDR characteristics show variations from dark to illumination conditions. Temperature effects on the NDRs of the DTOS are also obvious. The illumination and temperature influences on the device characteristics are investigated in this paper.     

Investigation of negative differential resistance phenomena inGaSb/AlSb/InAs/GaSb/AlSb/InAs structures

The negative differential resistance (NDR) phenomena were observed in GaSb/AlSb/InAs/-GaSb/AlSb/InAs resonant interband tunnel structures. Electrons have resonantly achieved interband tunneling through the InAs/GaSb broken-gap quantum well. The InAs well width causes significant variations of the peak current density and NDR behaviors. The peak current density varies exponentially with the AlSb barrier thickness. The multiple NDR behavior was observed with appropriate InAs well and AlSb barrier thicknesses, e.g., 30 Å thick AlSb barrier and 240 Å wide InAs well. Only single negative resistance has, otherwise, been seen. The three-band model was used to interpret the effect of the InAs well and AlSb barrier on the current-voltage characteristics of GaSb/AlSb/InAs/GaSb/AlSb/InAs structures     

MIDyM隧道发光二极管的研究

稀土元素Dy引入以玻璃为基底的隧道发光二极管（简称为MIDyMTD）后，其发光强度得到了明显提高，Ⅰ－Ⅴ特性的负阻现象变弱，并出现了较弱的量子共振隧穿现象。量子共振隧穿导致了起发光中介作用的SPP慢模式的增强，最终导致了MIDyMTD发光的增强。另外，以铌酸锂单晶片为基底的MIDYMTD出现了较大的负阻（峰：谷—7：1），并且发射光谱的短波方向出现了戏剧性的增加。     

Controlling Phase-Coherent Electron Transport in III-Nitrides: Toward Room Temperature Negative Differential Resistance in AlGaN/GaN Double Barrier Structures

Resonant tunneling of electrons is important for the manufacture of high-speed electronic oscillators and the electron injection control in quantum cascade lasers. In this work, room temperature negative differential resistance (NDR) in AlGaN/GaN double barrier structure with AlN/GaN digital alloy (DA) barriers is demonstrated. The peak-to-valley current ratio (PVCR) ranges from 1.1 to 1.24 at room temperature and becomes 1.5 to 2.96 at low temperatures, whereas no NDR is observed in double barrier structures with conventional ternary AlGaN barriers. The room temperature NDR together with the high PVCR at low temperature is attributed to the suppression of alloy disorder scattering by introducing AlN/GaN DA barriers. This work presents the successful control of phase-coherent electron transport in III-nitride heterostructures and is expected to benefit the future design of nitride-based resonant tunneling structures and high-speed electronic devices.     

共振隧穿二极管(RTD)的物理模型——共振隧穿器件讲座(3)

介绍了共振隧穿二极管物理模型的量子力学基础,重点讲解共振隧穿两种物理模型,从不同维度隧穿的特点分析共振隧穿和非共振隧穿的区别,为以后讨论分析共振隧穿器件的特性奠定基础。     

Well-defined electrical properties of high-strain resonant interband tunneling structure

The GaAs/InAs high-strain resonant interband tunneling diodes (HSRITDs) have been implemented by metal organic chemical vapor deposition (MOCVD). The current-voltage characteristics of variable quantum well and barrier thickness grown on (1 1 1) GaAs substrates are investigated. Experimental results reveal that the quantum barrier and well layer will influence current-voltage properties such as the peak current density, valley current density, and peak-to-valley current ratio (PVCR). Both peak current and valley current density decrease with increasing layers width. This result also exhibits the variation of PVCR with layers width.     

共振隧穿器件及其集成技术发展趋势和最新进展

介绍了共振隧穿器件及其特点,论述了该类器件及其集成技术的发展趋势和最新进展,特别是SiO 2S/iS/iO 2共振隧穿二极管及其集成电路的研制成功是一个突破性的进展。     

Simulation of quantum transport in monolithic ICs based on In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As RTDs and HEMTs with a quantum hydrodynamic transport model

A new quantum hydrodynamic transport model based on a quantum fluid model is used for numerical calculations of different quantum sized devices. The simulation of monolithic integrated circuits of resonant tunneling structures and high electron mobility transistors (HEMT) based on In/sub 053/Ga/sub 0.47/As-In/sub 052/Al/sub 0.48/As-InP is demonstrated. With the new model, it is possible to describe quantum mechanical transport phenomena like resonant tunneling of carriers through potential barriers and particle accumulation in quantum wells. Different structure variations, especially the resonant tunneling diode area and the gate width of the HEMT structure, show variable modulations in the output characteristics of the monolithic integrated device.