磁受限半导体异质结构中δ-掺杂与量子调控研究

Utilizing the theoretical analysis together with the numerical calculation, the δ-doping and its influence on three kinds of significant quantum effects (the wave-vector filtering effect, the giant magnetoresistance effect and the electron-spin filtering effect) are investigated in three classes of typical magnetically restricted semiconductor heterostructures (the magnetic-barrier nanostructure, the hybrid magnetic-electric-barrier nanostructure and the magnetic -barrier nanostructure with the spin-orbit coupling, which have been actualized or can be actualized in experiments), to explore the new way to realize the quantum manipulating in the semiconductor nanostructure. This project intends to calculate the transmission coefficient for electrons tunneling through the realistic magnetically restricted semiconductor heterostructure, by numerically solving the Schr?dinger equation, with the help of the improved transfer-matrix method (ITMM). By means of the well-known Landaur-Büttiker theory (LBT),the electronic conductance at zero temperature can then be calculated by numerically integrating the transmission coefficient. And then, the magnetoresistance (MR) ratio and the degree of the electron-spin polarization can be given accordingly.Thus,the generalized rule of the influences of the δ-doping on quantum effects in magnetically restricted semiconductor heterostructures can be revealed. The basical principle to structurally realize the quantum manipulating in magnetically restricted semicondutor heterostructures by utilizing the δ-doping technique can be elucidated. It can be expected that, an effective quantum manipulating method to the semiconductor nanostructure can be achieved by the actualization of this project, and a type of nanoelectronic devices also can be obtained, which will provide some theoretical instructions in designing, exploiting and applying new-pattern and controllable semiconductor electronic devices.

采用理论分析和数值计算相结合的方法，研究实验上已实现的或可以实现的三种典型磁受限半导体异质结构（磁垒纳米结构、复合磁电垒纳米结构、含自旋-轨道耦合磁垒纳米结构）中的δ-掺杂，及其对磁受限半导体异质结构中三种重要量子效应（波矢过滤效应、巨磁阻效应、自旋过滤效应）的影响，探索半导体纳米结构量子调控的新途径。本项目拟采用改进了的转移矩阵法（ITMM 方法）数值求解电子的薛定谔方程，计算电子的透射系数，利用Landaur-Büttiker超微结构电导理论（LBT方法）由透射系数计算电导，进而给出磁阻(MR)比率和电子的自旋极化度，从而揭示δ-掺杂对磁受限半导体异质结构中量子效应影响的一般规律，阐明利用δ-掺杂技术、从结构上实现磁受限半导体异质结构量子调控的原理，期望获得一种半导体纳米结构量子调控的有效方法与一类纳米电子器件，为新型可控半导体电子器件的设计、开发与应用提供理论指导。

由于低维度、小尺寸与量子受限，半导体纳米结构拥有丰富的量子效应，可被用于开发新型纳米电子器件。针对半导体纳米结构中量子效应及其调控的基本科学问题，本项目以一类重要的半导体纳米结构为研究对象，采用理论分析与数值计算相结合的方法研究磁受限半导体异质结构（MCSH）中的δ-掺杂，揭示其对MCSH结构中波矢过滤、巨磁阻和自旋过滤效应影响的规律，探索半导体纳米结构量子调控的新途径，设计新型纳米电子器件。. 建立δ-掺杂MCSH结构中电子输运的理论、方法与计算程序，可为同行提供借鉴与参考。分析和计算实验上已实现的或可以被实现的磁垒型和复合磁电垒型等MCSH结构中巨磁阻效应，发现即使引入δ-掺杂MCSH结构中仍存在相当的巨磁阻效应，而且磁阻比率与δ-掺杂密切相关，为磁信息存储开发结构可控的巨磁阻器件。研究δ-掺杂对磁垒型与复合磁电垒型磁受限GaAs/AlxGa1-xAs异质结构中波矢过滤效应的影响，发现调节δ-掺杂的权重和/或位置可实现MCSH结构中波矢过滤效率的控制，获得结构上可调的电子动量过滤器件。考虑构建在InAs/AlxIn1-xAs半导体异质结上的磁垒、复合磁电垒纳米结构中的自旋-轨道耦合效应（SOC，包括Rashba型和Dresselhaus型），发现MCSH结构中电子自旋过滤效应可通过改变界面限制电场或应力工程进行调控，提出SOC可调的电子自旋过滤器与空间自旋分裂器件。. 本项目取得的研究成果有助于理解半导体纳米结构中的量子效应及其调控的科学内涵，以及利用δ-掺杂从结构上实现半导体纳米结构中量子调控的物理机制。指导相关的实验研究工作，为纳米电子学应用设计、开发可控的波矢过滤、巨磁阻、自旋过滤与空间自旋分裂等电子器件。