Low Schottky Barrier Black Phosphorus Field‐Effect Devices with Ferromagnetic Tunnel Contacts

Black phosphorus (BP) has been recently unveiled as a promising 2D direct bandgap semiconducting material. Here, ambipolar field‐effect transistor behavior of nanolayers of BP with ferromagnetic tunnel contacts is reported. Using TiO 2 /Co contacts, a reduced Schottky barrier <50 meV, which can be tuned further by the gate voltage, is obtained. Eminently, a good transistor performance is achieved in the devices discussed here, with drain current modulation of four to six orders of magnitude and a mobility of μ h ≈ 155 cm 2 V −1 s −1 for hole conduction at room temperature. Magnetoresistance calculations using a spin diffusion model reveal that the source–drain contact resistances in the BP device can be tuned by gate voltage to an optimal range for injection and detection of spin‐polarized holes. The results of the study demonstrate the prospect of BP nanolayers for efficient nanoelectronic and spintronic devices.