Current-transport mechanisms of isotype n-ZnO/n-GaN heterostructures

Abstract

Electrical properties of n-ZnO/n-GaN isotype heterostructures prepared by rf-sputtering of ZnO films on GaN layers which in turn grown by metal-organic vapour phase epitaxy are discussed. Current-voltage (I-V) characteristics of the nZnO/n-GaN diodes exhibited highly rectifying characteristics with forward and reverse currents being ~1.43×10 -2 A/cm 2 and ~2.4×10 -4 A/cm 2 , respectively, at ±5 V. From the Arrhenius plot built representing the temperature dependent current-voltage characteristics (I-V-T) an activation energy 0.125 eV was derived for the reverse bias leakage current path, and 0.62 eV for the band offset from forward bias measurements. From electron-beam induced current measurements and depending on excitation conditions the minority carrier diffusion length in ZnO was estimated in the range 0.125-0.175 µm,. The temperature dependent EBIC measurements yielded an activation energy of 0.462 ± 0.073 V.