NMR Studies of Defects in Semiconductors

本研究涉及应用核磁共振（NMR）来研究半导体材料中特定类别的缺陷。氢与掺杂剂络合的研究将与工业伙伴合作进行，这些合作伙伴关注在加工和设备制造过程中引入半导体的氢的影响。该计划将集中在三个具体目标：氢与砷化镓和硅半导体中的掺杂物络合的位置和动力学将使用双共振技术来选择性地探测络合物。在砷化镓和相关材料中热生成的顺磁缺陷的识别和表征将使用原位高温核磁共振技术进行。将研究II-VI材料中铟杂质占据的位置和空位杂质配合物的表征，包括使用摄动角相关技术对这些缺陷进行同步研究的结果的相关性。用于电子器件的半导体材料的性能主要受杂质和晶体缺陷的影响。这些影响可以是建设性的，就像在“掺杂”的情况下，特定的杂质可以用来获得所需的电性能。另一方面，在材料加工过程中使用的有机材料中偶然引入的氢可能是高度有害的。氢可以“钝化”或中和掺杂杂质，使其失去电活性。半导体材料中不希望的和特征不佳的缺陷导致低产量和器件故障。充分了解的缺陷的开发具有开发具有改进特性的先进半导体材料的潜力。核磁共振（NMR）将被用于表征各种重要技术材料（包括硅、砷化镓和碲化镉）在原子尺度上缺陷的位置和运动特性。该技术具有高度选择性，能够探测晶体半导体中特定位置的单个化学物质。最近核磁共振技术的改进和高场超导磁体的使用使得在低至百万分之几十的浓度下研究某些缺陷物种成为可能。

This research involves the application of nuclear magnetic resonance (NMR) to the study of specific classes of defects in semiconducting materials. Studies of hydrogen complexed with dopants will be carried out in collaboration with industrial partners concerned about the effects of hydrogen introduced into semiconductors during processing and device fabrication. The program will focus on three specific goals: The location and dynamics of hydrogen complexed with dopants in gallium arsenide and silicon semiconductors will be determined using double resonance techniques to selectively probe the complex. The identification and characterization of thermally generated paramagnetic defects in gallium arsenide and related materials will be undertaken using in situ high temperature NMR techniques. The sites occupied by indium impurities and characterization of vacancy-impurity complexes in II-VI materials, including correlation of the results with concurrent studies of these defects using perturbed angular correlation techniques, will be studied. %%% The performance of semiconducting materials used in electronic devices is dominated by the effects of impurities and crystalline defects. These effects can be constructive, as in the case of "doping," where specific impurities can be used to obtain desired electrical properties. On the other hand, the incidental introduction of hydrogen into semiconductors from organic materials used during material processing can be highly deleterious. Hydrogen can "passivate," or neutralize dopant impurities, rendering them electrically inactive. Undesired and poorly characterized defects in semiconducting materials lead to poor yields and device failures. Exploitation of well-understood defects holds the potential for development of advanced semiconducting materials with improved characteristics. Nuclear magnetic resonance (NMR) will be used to characterize the location and motional properties of defects on the atomic scale in various materials of technological importance including silicon, gallium arsenide, and cadmium telluride. This technique is highly selective and is capable of probing individual chemical species in specific locations in a crystalline semiconductor. Recent improvements in NMR techniques and the use of high field superconducting magnets make it possible to investigate certain defect species at concentrations as low as a few tens of parts per million.