Dual-mode operation of a Pd/AlN/SiC device for hydrogen sensing

The electrical response of a hydrogen-sensing device is either a rectifying diode-type or a capacitor-type but could not be operated simultaneously in both the modes. However, we are able to demonstrate that a Pd/AlN/SiC device can operate in dual mode either as a rectifying diode or a capacitor. The device with a 50 nm AlN layer shows a shift of ∼0.35 V for 100 ppm H2 in both the modes, at a temperature of 150 °C. It seems that the presence of donor levels in the bandgap of the AlN layer with a wide range of energy is responsible for the observed electrical behavior of this device.