Temperature-dependent carrier transport behaviors in phosphorus-doped silicon nanocrystals/silicon carbide multilayers

Abstract

Size-controllable silicon nanocrystals/silicon carbide multilayers with various phosphorus-doping ratios are fabricated by plasma enhanced chemical vapor deposition system. The carrier concentration of Si NCs with suitable doping levels can be enhanced by six orders of magnitude than that of the un-doped sample and the room temperature conductivity can reach as high as 111 S/cm. The temperature-dependent carrier transport behaviors of the P-doped samples are systematically studied. It is revealed that the carrier transport behaviors are dominated by three different conduction mechanisms in the various temperature range, i.e. Mott variable-range hopping (within 20–80 K), multiple phonon hopping (within 80–300 K) and thermally activation conduction (above 300 K). Meanwhile, the carrier transport mechanism depends on the doping levels. At high doping levels, the localization length is about seven times of the size of dot diameters which may induce the metal-insulator transition.