Impact of Ge Content and Recess Depth on the Leakage Current in Strained $\hbox{Si}_{1-x}\hbox{Ge}_{x}/\hbox{Si}$ Heterojunctions

A study of the impact of the Ge content and the recess depth on the leakage current of strained
$\hbox{Si}_{1-x}\hbox{Ge}_{x}/\hbox{Si}$

$\hbox{p}^{+}\hbox{n}$
heterojunctions is presented. A rise in the current, when the Ge content increases and/or the recess depth decreases, is experimentally observed. An analysis of the physical variables involved in the leakage current at low electric fields is carried out. The Shockley–Read–Hall lifetime is identified as the variable that affects the leakage current the most. Changes in the lifetimes are correlated to changes in the Ge content and the recess depth (
$\hbox{Si}_{1-x}\hbox{Ge}_{x}$
thickness) by means of modifications of the stress levels. An expression that directly relates the values of the lifetimes with the germanium content is proposed.