Nuclear Magnetic Resonance Studies of Impurities in Semiconductors

9623299沃伦杂质物种核磁共振将用于研究晶体半导体中杂质的局域原子和电子结构。我们以前对Si(P)和Si(B)中施主和受主能带在100-500K范围内的变温研究将扩展到液氦温度。第三类杂质Ga和In In II-VI材料将在低温下存在持续光导的情况下，用常规的杂质核核磁共振进行研究。我们将尝试观察氧化锌及相关的II-VI材料的光学核偏振。光激发对杂质的局域原子结构的影响将作为对这些材料的“DX模型”的检验而被研究。%的杂质原子在具有重要技术意义的半导体晶体中发挥着关键作用，因为它们引入了材料导电所需的带电载流子。尽管它们很重要，但许多重要杂质的原子尺度环境仍然知之甚少。核磁共振提供了一种高度局域的、化学特异性的探针，将在本研究中用于研究材料中选定杂质的结构和电子环境，如CdTe和Si。为了理解为什么这些杂质与常规行为相反，这些杂质不会引入载流子，镉镉及相关材料中的Ga和In等原子的状态将受到特别的关注。在硅中，核磁共振将被用来阐明P或B杂质之间的相互作用如何影响载流子迁移率，从而影响硅基器件的性能。***

9623299 Warren Impurity-species nuclear magnetic resonance (NMR) will be used to investigate the local atomic and electronic structure of impurities in crystalline semiconductors. Our previous variable-temperature studies of the donor and acceptor bands in Si(P) and Si(B) in the range 100 - 500 K will be extended to liquid helium temperatures. The group III impurities Ga and In in II-VI materials will be studied by conventional impurity-nucleus NMR in the presence of persistent photoconductivity at low temperatures. An attempt will be made to observe optical nuclear polarization in ZnO and related II-VI materials. The effect of optical excitation on the local atomic structure of impurities such as Ga in CdTe will be examined as a test of the "DX model" of these materials. %%% Impurity atoms play a critical role in technologically important semiconducting crystals since they introduce the charged carriers necessary for the materials to conduct electricity. Despite their importance, the atomic-scale environments of many important impurities are still poorly understood. Nuclear magnetic resonance (NMR) provides a highly local, chemically-specific probe which will be used in this research to investigate the structural and electronic environments of selected impurities in materials such as CdTe and Si. The state of atoms such as Ga and In in CdTe and related materials will receive particular attention in an attempt to understand why these impurities, contrary to conventional behavior, do not introduce carriers. In Si, NMR will be used to clarify the way in which interactions between P or B impurities influence the carrier mobility and hence, the performance of silicon-based devices. ***