| AVS 65th International Symposium & Exhibition | |
| Thin Films Division | Wednesday Sessions |
| Session TF+EM+MI-WeM |
| Session: | Thin Film Processes for Electronics and Optics I |
| Presenter: | Alexander C. Kozen, U.S. Naval Research Laboratory |
| Authors: | A.C. Kozen, U.S. Naval Research Laboratory Z.R. Robinson, The College at Brockport - SUNY A.H. Rowley, The College at Brockport - SUNY T.J. Larrabee, U.S. Naval Research Laboratory M.E. Twigg, U.S. Naval Research Laboratory H.S. Cho, U.S. Naval Research Laboratory S.M. Prokes, U.S. Naval Research Laboratory |
| Correspondent: | Click to Email |
The niobium oxide system has seen recent interest, particularly due to its potential use as both a non-volatile, in the case of Nb2O5, or volatile, in the case of NbO2, memristor material. Nb2O5 is a high k dielectric (k~41) with a high refractive index (n~2.2) and a wide bandgap (3.5 eV), while NbO2 is a thermochromic material with a lower bandgap (1.2 eV) that undergoes a first order crystalline phase transition at a critical temperature (Tc) of 800˚C. Both of these phases, along with their intermediate sub-oxides, can serve as material components of memristors to facilitate low-power neural computing hardware.
We will examine the impact of annealing temperature, duration, and atmospheric chemistry on the phase selectivity of the NbOx thin films fabricated using atomic layer deposition. Anneals of stoichiometric amorphous Nb2O5 films are kinetically limited by both Nb5+ to Nb4+ reduction and crystallization steps, and we find that the addition of H2 during annealing is critical for the Nb5+ to Nb4+ reduction. To remove this kinetic-limiting step, we instead deposit reduced amorphous NbO2 films, which crystallize at lower temperatures. We investigate the optical and electrical properties of both amorphous and crystalline NbOx films and discuss the utility of the NbOx materials system to the fabrication of memristor materials.