> 10²⁰ cm^-3 n-doping in Ge by Sb/P co-implants: n⁺/p Diodes with improved rectification

One of the greatest challenges for fabricating a Ge channel n-MOSFET is to achieve high n-type dopant activation within the source and drain regions. Currently, p+ doping greater than 1020cm-3 can be routinely achieved which is close to the theoretical solid solubility limit of B in Ge. However, typical n+ doping of Ge is limited to less than 5×1019 which is far below the solid solubility limit of P in Ge. This work is aimed at achieving n+ doping of greater than 10 20cm-3 in Ge. In this paper, we describe a Sb and P co-implantation process to enhance n+ activation in Ge. N-carrier concentration more than 1.0×1020/cm3 has been demonstrated by this method. Furthermore, higher forward bias current in Ge n+/p junction diode is obtained from n+ formation by Sb and P co-implantion, as a consequence of the high n-type dopant activation in Ge. ©The Electrochemical Society.