Characterization of RF magnetron-sputtered a-BOxNy/ZnO MIS structures for transparent electronics

X-ray photoelectron spectroscopy (XPS) confirmed that RF magnetron sputtering of h-BN onto unheated substrates produced a-BOxNy films under all of the sputtering conditions studied. The surface roughness improved and pinholes were eliminated as the deposition pressure increased. Analysis of the current density dependence on the electric field of the a-BOxNy films suggests field-enhanced Schottky emission and/or Frenkel-Poole emission transport mechanisms. The highest breakdown strength obtained was 8 MV cm−1. A bandgap of 3.9 eV was confirmed by spectroscopic ellipsometry and UV–Vis spectroscopy. An interface trap concentration (Nit) of 7.3 × 1010 cm−2 and interface state density (Nss) of 7.5 × 1012 eV−1 cm−2 were measured for transparent ITO/a-BOxNy/ZnO metal–insulator-semiconductor (MIS) structures. Approximately, 2 V was required to switch the a-BOxNy/ZnO interface from accumulation to inversion.