Steep-Slope Threshold Switch Enabled by Pulsed-Laser-Induced Phase Transformation.

Super-steep two-terminal electronic devices using NbO, which abruptly switch from insulator to metal at a threshold voltage (), offer diverse strategies for energy-efficient and high-density device architecture to overcome fundamental limitation in current electronics. However, the tight control of stoichiometry and high-temperature processing limit practical implementation of NbO as a component of device integration. Here, we demonstrate a facile room-temperature process that uses solid-solid phase transformation induced by pulsed laser to fabricate NbO-based threshold switches. Interestingly, pulsed laser annealing under a reducing environment facilitates a two-step nucleation pathway (a-NbO → o-NbO → t-NbO) of the threshold-enabled NbO phase mediated by oxygen vacancies in o-NbO. The laser-annealed devices with embedded NbO crystallites exhibit excellent threshold device performance with low off-current and high on/off current ratio. Our strategy that exploits the interactions of pulsed lasers with multivalent metal oxides can guide the development of a rational route to achieve NbO-based threshold switches that are compatible with current semiconductor fabrication technology.