Steeds J W, Sullivan W, Wotherspoon A, Hayes J M
Department of Physics, University of Bristol, Bristol BS8 1TL, UK.
J Phys Condens Matter. 2009 Sep 9;21(36):364219. doi: 10.1088/0953-8984/21/36/364219. Epub 2009 Aug 19.
A series of electron irradiations has been performed on diamond and 4H SiC single crystal specimens. A wide range of different doses and dose rates was investigated. In addition, a more limited investigation of localized hydrogen and helium implantation of 4H SiC has been made. The electron energies were sufficient to cause atomic displacements creating vacancies and self-interstitials in the irradiated samples. After electron-irradiation or implantation the samples were studied by low temperature (∼7 K) photoluminescence microscopy. It was found that some of the defect centres migrated over large distances outside of the irradiated regions and that this distance increased with increase of the dose. Two possible explanations for this remarkable behaviour are discussed. One is based on the absorption by the defects of light created by recombination of electrons and holes in the irradiated or implanted region. The other deals with the consequences of recombination-enhanced migration at point defects that traps carriers as they are driven out of the irradiated region by electric fields created during the irradiation or implantation process. Interstitial atoms are deduced as migrating further than vacancies in this process.
对金刚石和4H碳化硅单晶样品进行了一系列电子辐照。研究了广泛的不同剂量和剂量率。此外，还对4H碳化硅的局部氢和氦注入进行了更有限的研究。电子能量足以引起原子位移，在辐照样品中产生空位和自间隙原子。电子辐照或注入后，通过低温（约7K）光致发光显微镜对样品进行研究。发现一些缺陷中心在辐照区域外迁移了很长距离，并且这个距离随着剂量的增加而增加。讨论了这种显著行为的两种可能解释。一种基于缺陷对辐照或注入区域中电子与空穴复合产生的光的吸收。另一种涉及在辐照或注入过程中产生的电场将载流子驱出辐照区域时，点缺陷处复合增强迁移的后果。在此过程中，推断间隙原子比空位迁移得更远。
