Low Specific Contact Resistivity to n-Ge and Well-Behaved Ge ${\rm n}^{+}/{\rm p}$ Diode Achieved by Multiple Implantation and Multiple Annealing Technique

Abstract

In this letter, the specific contact resistivity of metal on n-doped germanium is significantly reduced to <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$3.8\times 10^{-7}~\Omega\cdot {\rm cm}^{2}$</tex></formula> by <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm P}^{+}$</tex></formula> multiple implantation and multiple annealing (MIMA) technique. The dramatic reduction of specific contact resistivity is attributed to the enhanced activation of n-type dopants, and a high electrical activation over <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$1\times 10^{20}~{\rm cm}^{-3}$</tex></formula> is demonstrated by the spreading resistance profiling analysis. In addition, the fabricated germanium <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">${\rm n}^{+}/{\rm p}$</tex></formula> diode by <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm P}^{+}$</tex></formula> MIMA technique exhibits an <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$I_{\rm ON}/I_{\rm OFF}$</tex></formula> ratio over <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$10^{5}$</tex></formula> with low ideality factor of 1.11. The low specific contact resistivity of metal on n-doped germanium and well-behaved germanium <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\rm n}^{+}/{\rm p}$</tex></formula> diode are beneficial for the performance improvement of Ge nMOSFETs.