Effect of hydrogen peroxide treatment on the electrical characteristics of Au/ZnO epitaxial Schottky diode

Conversion from ohmic to rectifying behavior has been observed on Au/n-ZnO contacts with hydrogen peroxide pre-treatment of ZnO epitaxial layers. The Au contact on conventionally cleaned films showed leaky behavior with a high leakage current of 6 μA at a reverse bias voltage of −5 V. The ZnO epitaxial layers were treated with H2O2 at room temperature and at 100 °C for 3 min each. The epitaxial layers treated with H2O2 at room temperature for 3 min showed the best rectifying behavior with a leakage current of 2×10−9 A under −5 V reverse bias voltage. For this Schottky diode, the barrier height and ideality factor as calculated from current–voltage (I–V) measurements were 0.85 eV and 3.3, respectively. X-ray photoelectron spectroscopy measurements on treated and untreated ZnO samples showed that the peroxide pre-treatment removed –OH contamination at the surface of ZnO, which ultimately lowered the conductivity of the surface conductive layer eventually leading to an improvement in the electrical behavior of Au/ZnO Schottky contacts.