The ${\sim } 3\,{\times } 10^{20}$ cm $^{-3}$ Electron Concentration and Low Specific Contact Resistivity of Phosphorus-Doped Ge on Si by In-Situ Chemical Vapor Deposition Doping and Laser Annealing

The phosphorus incorporation by chemical vapor deposition and activation by laser annealing reaches the electron concentration of
$\sim 3\times 10^{20}$
cm
$^{-3}$
. The pulsed laser not only activates the phosphorus but also produces the biaxial tensile strain of 0.35%. With the nickel germanide contact, the specific contact resistivity reaches as low as
$1.5\times 10^{-8}~\Omega $
-cm
²
by greatly reducing the tunneling distance. Due to 4% misfit between Ge and Si, there are still misfit dislocations near the Ge/Si interface. The misfit dislocations at the Ge/Si interface lead to the ideality factor of 1.6 for the Ge/Si hetero-junction diode with ON/OFF ratio of
$\sim 1\times 10^{5}$
.