Sensitivity of Pt/ZnO Schottky diode characteristics to hydrogen

Pt/ZnO Schottky diodes show changes in forward current of 0.3 mA at a forward bias of 0.5 V or alternatively a change of 50 mV bias at a fixed forward current of 8 mA when 5 ppm of H2 is introduced into a N2 ambient at 25 °C. The rectifying current–voltage (I–V) characteristic shows a nonreversible collapse to Ohmic behavior when as little as 50 ppm of H2 is present in the N2 ambient. At higher temperatures, the recovery is thermally activated with an activation energy of ∼0.25 eV. This suggests that introduction of hydrogen shallow donors into the ZnO is a contributor to the change in current of the diodes.