Synthesis of Single Electron Devices and Investigation of Their Circuits and Systems

我们研究了各种单电子（SE）和量子点（QD）器件及其电路和系统，以探索实现更好性能和前所未有功能的方法，总结如下。(1)新型嵌入InAs量子点的（GaAs/AlGaAs）场效应管。通过在每个点上捕获一个电子或空穴，证明了它们的记忆和光探测器功能。(2)利用导电AFM尖端选择性氧化GaSb/InAs体系，形成具有清晰特性的SE晶体管（SET）。(3)开发了一种新的硅兼容制造方法，将硅SOI-MOS通道挤压成量子点接触几何形状。该器件即使在300K时也具有清晰的SET特性，并用于形成二进制判定电流开关元件。(4)在主速率方程或扩展SPICE框架的基础上，改进了SE晶体管和存储器的建模和仿真方法。评估了大型SET系统的误码率，明确了对归一化比特能量（Eb/kT）和剩余电荷的要求。为了避免SET系统固有的不稳定性，提出了匹配滤波逻辑电路。(5)提出了二元决策图、多数逻辑、多电子态多值逻辑等新的SET结构，并明确了它们的特点。(6)此外，还研究了SE和QD系统对中红外（MIR）和太赫兹波的响应。利用量子点中被困电子的光离作用，成功地开发了新的MIR探测器。对三势垒结构的光子辅助隧穿过程进行了分析，结果表明其响应速度是双势垒结构的一万倍。

We investigated a variety of single-electron (SE) and quantum dot (QD) devices and their circuits and systems to explore ways to achieve better performances and unprecedented functions, as summarized below.(l) (GaAs/AlGaAs) FETs with embedded InAs QDs were newly developed. Their memory and photodetector functions were demonstrated by trapping a single electron or hole in each dot. (2) GaSb/InAs systems were selectively oxidized by a conductive AFM tip to form a SE transistor (SET) with clearcut characteristics. (3) Novel LSI-compatible fabrication method was developed to squeeze a Si SOI-MOS channel into a quantum point contact geometry. The device exhibited clear SET characteristics even at 300K and was used to form a binary-decision current switch element. (4) Improved methods to model and simulate SE transistors and memories were developed on the basis of the master rate equation or an extended SPICE framework. Bit error rates of large scale SET systems were assessed and requirements on the normalized bit energy (Eb/kT) and residual charges were clarified. Matched filter logic circuits were proposed to avoid the inherent instability of SET systems. (5) New SET architectures, such as binary decision diagrams, majority logic, and multi-valued logic using multi-electron states, were proposed and their features clarified. (6) Moreover, the response of SE and QD systems to midinfrared (MIR) and THz waves were investigated. New MIR detectors using the photoionization of trapped electrons in QDs were successfully developed. Photon assisted tunneling processes were analysed for triple- barrier SET geometries and were shown to have responsivity ten thousand times as large as that for double barrier geometries.