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Nb2N is trigonal omega structured and crystallizes in the trigonal P-3m1 space group. The structure is two-dimensional and consists of one Nb2N sheet oriented in the (0, 0, 1) direction. Nb is bonded in a distorted T-shaped geometry to three equivalent N atoms. All Nb–N bond lengths are 2.18 Å. N is bonded to six equivalent Nb atoms to form edge-sharing NNb6 octahedra.
Nb2N is beta Vanadium nitride structured and crystallizes in the trigonal P-31m space group. The structure is three-dimensional. Nb is bonded in a distorted T-shaped geometry to three N atoms. There are one shorter (2.17 Å) and two longer (2.18 Å) Nb–N bond lengths. There are two inequivalent N sites. In the first N site, N is bonded to six equivalent Nb atoms to form corner-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles are 48°. In the second N site, N is bonded to six equivalent Nb atoms to form a mixture of edge and corner-sharing NNb6 octahedra. The corner-sharing octahedral tilt angles are 48°.
(Nb2N)2(N2)3(Br)20 crystallizes in the tetragonal P4/mnc space group. The structure is zero-dimensional and consists of six ammonia molecules, twenty hydrobromic acid molecules, and two Nb2N clusters. In each Nb2N cluster, Nb5+ is bonded in a single-bond geometry to one N3- atom. The Nb–N bond length is 1.88 Å. N3- is bonded in a linear geometry to two equivalent Nb5+ atoms.
We report the properties of molecular beam epitaxy deposited AlBN thin films on a recently developed epitaxial nitride metal electrode, Nb2N. While a control AlN thin film exhibits standard capacitive behavior, distinct ferroelectric switching is observed in the AlBN films with increasing Boron mole fraction. The measured remnant polarization Pr∼15μC/cm2 and coercive field Ec∼ 1.45 MV/cm in these films are smaller than those recently reported on films deposited by sputtering, due to incomplete wake-up, limited by current leakage. Because AlBN preserves the ultrawide energy bandgap of AlN compared to other nitride hi-K dielectrics and ferroelectrics, and it can be epitaxially integrated with GaN and AlN semiconductors, its development will enable several opportunities for unique electronic, photonic, and memory devices.