NMR Studies of Defects in Semiconductors

这项研究涉及到应用核磁共振(核磁共振)来研究半导体材料中特定类别的缺陷。将与关心在加工和器件制造过程中引入到半导体中的氢的影响的工业合作伙伴合作，开展与掺杂剂络合的氢的研究。该计划将专注于三个具体目标：将使用双共振技术选择性地探测络合物，以确定与砷化镓和硅半导体中的掺杂剂络合的氢的位置和动力学。将利用原位高温核磁共振技术对砷化镓及其相关材料中热产生的顺磁缺陷进行鉴定和表征。将研究II-VI材料中铟杂质占据的位置和空位-杂质复合体的表征，包括结果与利用微扰角相关技术同时进行的这些缺陷的研究的相关性。电子设备中使用的半导体材料的性能受杂质和晶体缺陷的影响。这些效应可以是建设性的，就像“掺杂”的情况一样，在这种情况下，可以使用特定的杂质来获得所需的电特性。另一方面，在材料加工过程中使用的有机材料附带地将氢引入半导体可能是非常有害的。氢可以“钝化”或中和掺杂杂质，使它们在电学上不起作用。半导体材料中不受欢迎和特征不佳的缺陷会导致较低的成品率和器件故障。对众所周知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。核磁共振将被用来表征原子尺度上的缺陷在各种具有技术重要性的材料中的位置和运动特性，包括硅、砷化镓和碲化镉。这项技术具有很高的选择性，能够探测晶体半导体中特定位置的个别化学物种。最近核磁共振技术的进步和高场超导磁体的使用使研究某些浓度低至百万分之几十的缺陷物种成为可能。

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.