Opposite Effects of Doping on the Pop-In Phenomenon in InAs and Ge

The pop-in phenomenon, characterized by a sudden increase of displacement during the indentation of samples, usually signifies the incipient plastic deformation. Several reasons can cause the pop-in event, such as dislocation nucleation, phase transitions and cracking ¹. Previous studies have shown that electronic doping can influence the pop-in phenomenon in semiconductors ^{2, 3}, however, underlying mechanisms remain controversial. Here, we investigate doping effects on pop-in phenomenon in InAs and Ge by combining nanoindentation and DFT calculations. We find pop-in events disappear in doped InAs, resulting from the decreased energy barrier of dislocation nucleation. In Ge, pop-in events only occur in doped samples. According to literature, phase transition accounts for the pop-in event in Ge, indicating the increased phase transition barrier by doping. The pop-out event during unloading of Ge provides additional evidence of the phase transition. Our findings elucidate the mechanism of opposite effects of doping on pop-in phenomenon of InAs and Ge, connecting electronic structures to mechanical properties of semiconductors.<br/><br/>References:<br/>1. Ohmura T, Wakeda M. Pop-In Phenomenon as a Fundamental Plasticity Probed by Nanoindentation Technique. <i>Materials (Basel)</i> 2021, <b>14</b>(8).<br/>2. Nowak R, Chrobak D, Nagao S, Vodnick D, Berg M, Tukiainen A<i>, et al.</i> An electric current spike linked to nanoscale plasticity. <i>Nat Nanotechnol</i> 2009, <b>4</b>(5)<b>:</b> 287-291.<br/>3. Chrobak D, Ziolkowski G, Chrobak A. On Incipient Plasticity of InP Crystal: A Molecular Dynamics Study. <i>Materials (Basel)</i> 2021, <b>14</b>(15).