Development of in-situ Sb-Doped Ge1−xSnx Epitaxial Layers for Source/Drain Stressor of Strained Ge Transistors

We have investigated the crystalline and electrical characteristics of heavily doped n-type Ge
_1-x
Sn
_x
epitaxial layers with various Sb concentrations up to 10
²⁰
cm
^-3
. In this study, we focus the thermal stability of Sb doped Ge
_0.94
Sn
_0.06
and Ge epitaxial layers and clarify the relationship between the crystalline and electrical characteristics. At the as-grown condition, the substitutional Sb concentration was achieved at higher than 2.6×10
²⁰
cm
^-3
. After the post-deposition annealing, Sb-doped Ge
_1-x
Sn
_x
maintained their superior crystallinity up to 400 °C, while the sheet resistance increases with Sb segregation. We also found that Sb atoms doped in the Ge
_0.94
Sn
_0.06
layer show a higher thermal robustness at 300 °C than those in the Ge layer.