Composition dependent properties of p- and n-type polycrystalline group-IV alloy thin films

Group-IV alloy semiconductors have garnered increasing attention as advanced thin-film materials for next-generation electronics. We have demonstrated polycrystalline Ge thin films with the highest recorded crystallinity and carrier mobility using a multistep heating process in solid-phase crystallization. In this study, we apply these recent findings in Ge to Si1-xGex (x: 0-1) and Ge1-ySny (y: 0-0.04) alloys and investigate their crystal and electrical properties. For all compositions, controlling the temperature in each stage increases the grain size to the micrometer order, improving the carrier mobility and reducing the number of defect-induced acceptors. Sb doping further enlarges the grain size (up to 10 mu m) in addition to n-type conduction control, whereas the electron concentration varies with the composition. Both hole and electron mobilities significantly depend on the composition owing to the effects of carrier effective mass, grain size, and carrier concentration: the hole and electron mobilities peak at 350 and 150 cm(2) V(-1)s(-1), respectively. The relationship between the composition and various physical properties revealed in this study will contribute to the better understanding, control, and device application of polycrystalline thin films based on group-IV alloy semiconductors. (C) 2021 Elsevier B.V. All rights reserved.