Fabrication and Physics of Low-Disorder Electron and Hole Systems

这项研究涉及材料科学和物理学的研究 高质量GaAs/AlxGa 1-x异质结薄- 膜结构，使用分子束外延技术， 新的电子相互作用物理学预计将在这样的理想中出现 电子系统 极低无序度，稀二维（2D） GaAs/AlGaAs界面的电子和空穴系统 非常小的朗道水平填充的区域， 量子液体和系统的固体状态之间的预期 将被研究。 几种新颖的带有附加项的准二维系统 自由度也将被研究。 其中包括系统 其包含两层或多层紧密靠近的电子， 层间库仑相互作用很强， 宽抛物面威尔斯阱中的电子系统。 的附加度 这些结构中的自由预计将导致新的集体 例如最近观察到的分数量子霍尔态 在偶数1/2分母处填充双层电子 系统 这些系统将通过低温探测 磁输运测量 %%% 这项先进材料研究计划的影响是双重的。 首先，优化分子束外延生长技术， 产生非常高质量的选择性掺杂界面， 具有最少缺陷的异质结构薄膜 可用于其它先进半导体的制造 结构和设备。 其次，这些低无序结构将 使半导体物理学中的一个新的制度， 物理现象是由电子-电子 交互.

This research involves a study of the materials science and physics of the growth of very high-quality GaAs/AlxGa1-x heterojunction thin- film structures using the molecular beam epitaxy technique, and the new electron interaction physics expected to manifest in such ideal electron systems. Very low-disorder, dilute two-dimensional (2D) electron and hole systems at the GaAs/AlGaAs interface in the regime of very small Landau level fillings where transitions between quantum liquid and solid states of the system are expected will be studied. Several novel quasi-2d systems with an additional degree of freedom will also be studied. These include systems which contain two or more layers of electrons in close proximity so that interlayer Coulomb interactions are strong, and thick-layer electron systems in wide parabolic wells. The additional degree of freedom in these structures is expected to lead to new collective sates such as the recently observed fractional quantum Hall state at the even 1/2 denominator filling in a double-layer electron system. These systems will be probed via low-temperature magnetotransport measurements. %%% The impact of this advanced materials research program is two-fold. First, optimization of molecular beam epitaxy growth techniques to produce very high-quality, selectively-doped interfaces and heterostructure thin-films with the least amount of imperfections can be useful for the fabrication of other advanced semiconductor structures and devices. Second, these low-disorder structures will make accessible a new regime in semiconductor physics where new physical phenomena are expected to arise from the electron-electron interactions.