Study of Point Defects in Semiconductors using Optical Detection of Magnetic Resonance

利用磁共振光学检测研究半导体中的点缺陷

• 批准号: 9704386
• 负责人: George Watkins
• 金额: $ 28.45万
• 依托单位: Lehigh University
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-11-01 至 2001-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9704386&HistoricalAwards=false
• 关键词: Study; Point; Defects; Semiconductors; using

9704386 Watkins This experimental research project centers on the atomic scale defects present in technologically relevant semiconductors as probed by optical detection of magnetic resonance and by optically detected electron-nuclear double resonance. The defects of interest include intrinsic defects such as vacancies, interstitials and anti-sites, as well as important chemical impurities and simple complexes resulting from interactions between them. The purpose of the research is to understand the electronic and vibronic structure of the ground, metastable, and excited states of such defects, and to determine on a microscopic scale the role they play in the electronic and optical properties of this class of materials. The emphasis in the renewed research is toward the wide bandgap semiconductors, including II-VI compounds, III-V nitrides, diamond, and SiC. The rationale is that relatively little is known about the defects in these materials and there is good reason to anticipate surprises and new important physics in their properties. This is because of competition between the increased recombination energy available from the bandgap on the one hand, and the increased role of many- electron effects due to the greater electronic localization on the other. Theory is pressed in dealing with deep defects, and high quality experimental information will be useful to guide and test new theory. In addition, these materials are of technological interest for their potential as visible and uv light emitting and high temperature electronic devices. Such applications will require an understanding of point defects greatly in excess of what little is now known. A major experimental approach will be to produce intrinsic defects by 2.5MeV electron irradiation for study by the ODMR and ODENDOR techniques. In some cases irradiation in situ at 4.2K in a special ODMR facility will allow study of pristine Frenkel pair defects (vacancy-interstitial close pairs) at low temper ature and as they are slowly warmed. %%% This experimental project focuses on important atomic scale defect structures that occur in crystalline samples of semiconductors. Such defects, which include vacant lattice sites, additional atoms located interstitially, and chemical substitutions (as for example As as an impurity in Si) are well known to have important consequences on the electronic properties of semiconductors. Such point defects as As in Si introduce an extra electron for electrical conduction (these are called donor impurities); others introduce holes, and all point defects have a "scattering" effect on the motion of electrons and holes when an accelerating field is applied, tending to reduce the current for a given voltage. The present project makes use of an advanced optically detected magnetic resonance method for study of various point defects. The work will focus on those "wide bandgap" semiconductors which are now being considered for unique applications for which silicon and gallium arsenide are not suitable. Possible applications of the wide bandgap semiconductors are for visible and ultraviolet light emitting diodes and for high temperature electronic devices. The semiconductors of interest include, for example, SiC and GaN. A special aspect of the experimental work will be deliberate introduction of point defects by electron irradiation. This work involves a postdoctoral fellow who will be excellently trained in the course of this research for a position in industry, government, or academia. ***

9704386 Watkins这个实验研究项目的中心是通过光学检测磁共振和光学检测电子-核双共振来探测技术相关半导体中存在的原子尺度缺陷。所关注的缺陷包括空位、间隙和反位等内在缺陷，以及它们之间相互作用产生的重要化学杂质和简单配合物。本研究的目的是了解这类缺陷的基态、亚稳态和激发态的电子和振动结构，并在微观尺度上确定它们在这类材料的电子和光学性质中所起的作用。新研究的重点是宽禁带半导体，包括II-VI化合物、III-V氮化物、金刚石和SiC。其基本原理是，人们对这些材料的缺陷所知相对较少，因此有充分的理由预测它们的性质会出现惊喜和新的重要物理现象。这一方面是因为从带隙中获得的增加的复合能与由于更大的电子局域化而增加的多电子效应之间的竞争。理论在处理深层缺陷时是有压力的，而高质量的实验信息将有助于指导和检验新的理论。此外，这些材料具有作为可见光和紫外光发射和高温电子器件的潜力，因此具有技术上的兴趣。这样的应用将需要对点缺陷的理解远远超过目前所知的。一个主要的实验方法将是通过2.5MeV的电子辐照产生内在缺陷，以供ODMR和ODENDOR技术研究。在某些情况下，在一个特殊的ODMR设施中，在4.2K的原位辐照将允许在低温和缓慢升温时研究原始的Frenkel对缺陷（空位-间隙闭合对）。这个实验项目的重点是发生在半导体晶体样品中的重要原子尺度缺陷结构。这类缺陷，包括空位点位、位于间隙的附加原子和化学取代（如硅中的杂质as），众所周知对半导体的电子特性有重要影响。像Si中的as这样的点缺陷引入了一个额外的电子来导电（这些被称为供体杂质）；另一些则引入空穴，当施加加速场时，所有的点缺陷都会对电子和空穴的运动产生“散射”效应，倾向于在给定电压下减小电流。本项目利用一种先进的光学探测磁共振方法来研究各种点缺陷。这项工作将集中在那些“宽带隙”半导体上，这些半导体目前正在考虑用于硅和砷化镓不适合的独特应用。宽禁带半导体的可能应用是可见光和紫外线发光二极管和高温电子器件。感兴趣的半导体包括，例如，SiC和GaN。实验工作的一个特殊方面是通过电子辐照有意引入点缺陷。这项工作需要一名博士后，他将在这项研究的过程中获得优秀的培训，并在工业、政府或学术界担任职务。＊＊＊