Record low specific contact resistivity (1.2×10−9 Ω-cm2) for P-type semiconductors: Incorporation of Sn into Ge and in-Situ Ga doping
Record-low specific contact resistivity ρ<inf>c</inf> down to 1.2×10<sup>−9</sup> Ω-cm<sup>2</sup> is achieved for Ti/p<sup>+</sup>-Ge<inf>0.95</inf>Sn<inf>0.05</inf> contact by incorporating Sn into Ge and insitu Ga doping with active doping concentration of 1.6×10<sup>20</sup> cm<sup>−3</sup>. As compared with Ni(GeSn)/p<sup>+</sup>-Ge<inf>0.95</inf>Sn<inf>0.05</inf> contact, Ti/p<sup>+</sup>-Ge<inf>0.95</inf>Sn<inf>0.05</inf> contact exhibits lower ρ<inf>c</inf> and is more thermally stable. In addition, theoretical calculation shows that for a given doping concentration, incorporating Sn into Ge lowers the p<inf>c</inf> as compared with metal/p-Ge contacts.