Electrical characterisation of epitaxial AlN/Nb2N heterostructures grown by molecular beam epitaxy

Initial electrical characterisation of epitaxial AlN/Nb2N heterostructures grown by molecular beam epitaxy on 6H-SiC substrates is presented. Metal–insulator–metal (MIM) devices of varying diameter were used for current–voltage and capacitance–voltage (C–V) measurements at various temperatures. From C–V measurements, a dielectric constant of 10.1 was extracted along with a linear dependence of capacitance on temperature of 0.02 nF/cm2/°C. Leakage current was determined to be consistent with a Poole–Frenkel conduction mechanism at electric fields >1.25 MV/cm with an extracted trap ionisation energy of 0.82 eV. Electric field breakdown ranged between 3.4 and 5.6 MV/cm with some dependence on the diameter of the MIM device. These initial findings demonstrate the potential for high-power devices based on AlN.