Manipulating Dislocation Motion by Electric Fields and Illumination

Dislocations in semiconductors are typically less mobile than in metals, which causes the brittleness and insufficient mechanical reliability of semiconductors and their devices. It is well known that dislocation motion is a mechanical behavior which is driven by shear stress and could be influenced by environmental factors, like temperature ¹, electric fields ² and even illumination ³ as reported from decades ago. Therefore, manipulating dislocation motion through external stimuli, such as electric fields and illumination, holds promise for improving semiconductor manufacturing and applications. Despite its significance, dislocation dynamics under external stimuli, such as electric fields and illumination, is still elusive due to the lack of direct evidence of dislocation behavior. In this study, we visualize and analyze the dislocation evolution under electric fields and illumination by combining transmission electron microscopy (TEM), in situ electrical testing system, photo-nanoindentation and density functional theory (DFT) calculations. Under electric fields, we find electric fields drive dislocations motion even in the absence of mechanical loading. Dislocations can move back and forth depending on the direction of the electric field. We identify the non-stoichiometric nature of dislocation cores and determine their charge characteristics ⁴. Under illumination, we elucidate the reduced dislocation mobility through comparing the dislocation evolution to darkness. With DFT calculations, our research suggests that the increased barrier of dislocation glide, resulting from light-induced electrons and holes, account for the photo-plastic effect in semiconductors. This study provides direct experimental evidence of dislocation dynamics under electric fields and illumination, opening opportunities for dislocation engineering in semiconductors. For example, our findings suggest the potential use of electric fields to drive dislocations moving out of semiconductors, an alternative to traditional thermal annealing methods.<br/><br/>References:<br/>1. Hull D, Bacon DJ. <i>Introduction to dislocations</i>, vol. 37. Elsevier, 2011.<br/>2. Osip'yan YA, Petrenko VF, Zaretskii AV, Whitworth RW. Properties of II–VI semiconductors associated with moving dislocations. <i>Adv. Phys.</i> 1986, <b>35</b>(2)<b>:</b> 115-188.<br/>3. Koubaïti S, Couderc JJ, Levade C, Vanderschaeve G. Vickers indentation on the {001} faces of ZnS sphalerite under UV illumination and in darkness. Crack patterns and rosette microstructure. <i>Acta Mater.</i> 1996, <b>44</b>(8)<b>:</b> 3279-3291.<br/>4. Li M, Shen Y, Luo K, An Q, Gao P, Xiao P<i>, et al.</i> Harnessing dislocation motion using an electric field. <i>Nat. Mater.</i> 2023, <b>22</b>(8): 958-963.