Fabrication and properties of metal/ferroelectrics/semiconductor diodes on 4H–SiC

Polycrystalline PbTiO3 (PTO) films with pure perovskite phase were deposited directly on 4H n-type SiC substrates by pulsed laser ablation. By subsequent gold metallization, metal/ferroelectrics/semiconductor (MFS) diodes were fabricated. At room temperature the leakage current exhibits ohmic behavior at low voltages (<3 V), but at higher voltages (⩾6 V), it is Schottky emission dominated. Both the dielectric constant and the resistivity of the PTO layers are frequency dependent, decreasing monotonically with the increasing frequency. The capacitance–voltage (C–V) curves of the diodes demonstrate the typical hysteresis loop of a MFS diode structure, and carrier injection and memory effects are observed in the C–V measurements. The investigated MFS diode structure has tentative applications as a gate structure in a SiC field effect transistor or a nonvolatile memory cell on a SiC substrate.