Wannier-Stark localization in semiconductor superlattices

在本项目中，我们研究了半导体超晶格中的wanner - stark局域化现象，旨在阐明超薄量子异质结构在高电场作用下的基本光谱和隧道输运特性。在人工设计和制造的超晶格耦合量子阱系统中，由于斯塔克效应对量子化微带态的影响，出现了各种有趣的量子现象。主要采用光电流、光致发光、光致发光激发和电反射等光学方法，明确了影响光生载流子光谱结构和隧道输运特性的关键因素，涉及光吸收、光复合和隧道输运过程。本项目的研究结果如下：(1)不同微带宽度的GaAs/AlAs超晶格的基本带边吸收特性及其与微带色散的关系，(2)异质界面波动与光谱和侧向光致发光特性的关系，(3)Starkladder共振引起的动态透射强度振荡，(4)辐射复合与光致载流子的隧穿和侧向输运特性的关系，(5)与不同子带相关的Stark阶梯局域态之间的量子干涉；(6)激子Stark阶梯跃迁的振子强度及其对小带宽度的依赖；(7)准束缚Stark阶梯局域态的光学性质。

In this project we have investigated Wannier-Stark localization phenomena in semiconductor superlattices, aiming at clucidating the fundamental spectroscopic and tunneling transporl properties of the ultra-thin quantum heterostructures under high electric fields. In the artificially designed and fabricated superlattices as coupled-quantum-wells systems, varlous interesting quantum phenomena have emerged as a result of Stark effects on the quantized miniband states. By employing mainly optical methods such as photocurrent, photoluminescence, photoluminescence excitation and electroreflectance, key factors have been clarified which affect the spectroscopic structures and the tunneling transport properties of photogenerated carriers involving with optical absorption, recombination and tunneling processes. The following results are obtained from studies of this project : (1) fundamental band-edge absorption propeties of GaAs/AlAs superlattices with different miniband widths and their ralationship with the miniband dispersion, (2) correlation between the heterointerface fluctuations and the spectral and lateral photoluminescence properties, (3) dynamic transmission intensity oscillations due to the Starkladder resonances, (4) correlation between the radiative recombinations and tunneling and lateral transport properties of photogenaraied carriers, (5) quantum interference between the Stark ladder localized states associated with different subbands, (6) oscillator strengths of the excitonic Stark ladder transitions and their dependence on the miniband width, (7) optical properties of quasi-bound Stark ladder localized srates.