Germanium–Tin $\hbox{n}^{+}\hbox{/p}$ Junction Formed Using Phosphorus Ion Implant and 400 $^{\circ} \hbox{C}$ Rapid Thermal Anneal

AGe
_0.976
Sn
_0.024
n
⁺
/p diode was formed using phosphorus ion (P
⁺
) implant and rapid thermal annealing at 400°C. Activation of P in Ge typically requires high temperatures (e.g., 700°C), and it was found that this is not needed in the presence of a small amount of Sn. A high forward bias current of 320 A/cm
²
at -1 V is achieved for the Ge
_0.976
Sn
_0.024
n
⁺
/p diode. This is four times higher than that of the Ge n
⁺
/p control diode, which received the same P
⁺
implant but activated at 700°C. The n
⁺
-GeSn region has a high active dopant concentration of 2.1 × 10
¹⁹
× cm
^-3
, much higher than that in the Ge control. The increased active dopant concentration in GeSn reduces the width of the tunneling barrier between the Al contact and the n
⁺
-GeSn and increases the forward bias diode current. Enhancement of P activation in Ge
_0.976
Sn
_0.024
could possibly be as a result of passivation of vacancies in the Ge lattice due to Sn atoms.