Heterogeneous semiconductors: epitaxy and electronic properties

本文主要研究了非均相磁性半导体（MSC）的气相外延（VPE），如含有MnP纳米簇的GaP和基于III-V化合物的量子异质结构（QHS）。我们的主要兴趣是了解(i)固有结构与我们生长的材料的光学、磁性和输运性质之间的关系，以及（ii）这种结构如何受生长过程的支配。最近已经确定，含有磁性材料纳米团簇的非均相MSC脱膜的磁性取决于纳米团簇包裹体的大小、晶体结构和取向，并且已经建立了从我们生长的样品中提取这些信息的方案。然而，当从气相生长时，如何控制这些夹杂物的掺入却鲜为人知。因此，我们的目标之一是通过精心设计的生长实验和详细的材料表征来建立控制结构的基本机制。这也适用于我们正在进行的应变QHS研究，包括应变层超晶格和相干量子点层堆栈，我们将在其上加入用于红外光检测的新型稀释氮化物，以及用于热电研究的纳米内含物薄膜。我们将在我们的实验室中生长这些非均相半导体，为此我们有两个专用的金属有机VPE反应器，我们可以在那里生长磷化物，砷化物，锑化物和稀氮化物。我们将自己或通过多年来发展和维护的完善的合作者网络来充分描述脱毛者的特征。特别是，许多这些异质半导体中的载流子寿命很少受到关注，但它们将被用于各种设备的应用中。提出的大部分工作都是与先进材料和器件相关的基础性工作，并有望帮助建立进一步发展应用所需的基本理解，例如设计用于能量转换和节能、光子探测和光隔离的创新设备。

In this proposal we focus on the vapor phase epitaxy (VPE) of heterogeneous magnetic semiconductors (MSC), such as GaP containig nanoclusters of MnP, and of quantum heterostructures (QHS) based on III-V compounds. Our main interests are to understand (i) the relationship between the inherent structure and the optical, magnetic and transport properties of the materials we grow, and (ii) how this structure is governed by the growth processes. It has recently been determined that the magnetic properties of heterogeneous MSC epilayers containing nanoclusters of magnetic materials depend on the size, crystallographic structure and orientation of the nanocluster inclusions, and protocols have been established to extract this information from the samples we grow. Yet, little is known on how to control the incorporation of these inclusions when growing from the vapor phase. Thus, one of our objectives is to establish the basic mechanisms controlling the structure by carefully designed growth experiments followed by detailed material characterization. This also applies to our ongoing study of strained QHS, including strained-layer supperlattices and stacks of layers of coherent quantum dots to which we will incorporate new dilute nitride for applications in IR photo detection, and films with nanometric inclusions for thermoelectric studies. We will grow these heterogeneous semiconductors in our laboratory, and for this purpose we have two dedicated metal organic VPE reactors where we can grow phosphides, arsenides, antimonides and dilute nitrides. We will fully characterize the epilayers ourselves or through a well established network of collaborators developed and maintained through many years. In particular, the carriers' lifetimes in many of these heterogeneous semiconductors have received little attention, yet they will be needed for applications in a variety of devices. Most of the work proposed is of a fundamental nature related to advanced materials, and devices, and it is expected to help establish the basic understanding needed for further advances in applications, such as the design of innovative devices for energy conversion and energy conservation, photon detection and optical isolation.