Enhancement of Phosphorus Dopant Activation and Diffusion Suppression by Fluorine Co-Implant in Epitaxially Grown Germanium

To date, it is a major challenge to achieve in Ge n-MOSFETs low parasitic resistance and ultra shallow n+-p junction. Many studies indicate that vacancies that are present in n-doped Ge i) form electrically neutral donor-vacancy (DnV) pairs that reduce the amount of activated dopants, and ii) vacancy itself facilitates the enhanced dopant diffusion. In this work, we aim to achieve both higher activation level and less diffusion by passivating the vacancies with fluorine (F) implant.