  Two-dimensional (2D) intrinsic superconductors with nontrivial topological
band and vertical ferroelectricity exhibit fascinating characteristics to
achieving electrostatic control of quantum phases. While, only a few such 2D
materials have been theoretically predicted. In this work, based on first
principles calculations, we explore the superconductivity and ferroelectric
properties in fluorinated 2D Nb2N. In the stable Nb2NF2, H3-Nb2NF2 breaks the
spatial inversion symmetry, exhibiting vertical ferroelectric. More
interestingly, it not only possesses intrinsic superconductivity with
superconducting transition temperatures (Tc) of 10 K, but also exhibits
nontrivial band topology. While, H1-Nb2NF2 shows topological band and
superconductivity with Tc of 32 K, surpassing most of 2D conventional
topological superconductors' candidates. Our research has enriched 2D
superconducting materials with nontrivial band topology and ferroelectric
properties, and provided a theoretical basis for the preparation of devices
switching between superconducting and ferroelectric states with external
electric field.
