Performance of Electrodeposited Pt/InP Schottky Diode as a Hydrogen Sensing Head for InP-Based Wireless Sensor Chips

Hydrogen-sensing performances of Pt/InP Schottky diodes and MESFETs are evaluated from a viewpoint of constructing a nanometer-scale hydrogen sensor head of a future wireless hydrogen sensor chip. To realize large Schottky barrier heights (SBHs), Pt films were deposited by a pulsed in-situ electrochemical process. Upon exposure to hydrogen in air, the Pt/InP Schottky diode exhibited remarkably large increase of forward and reverse currents. The sensing mechanism is explained in terms of SBH changes caused by interface dipole formed at Pt/InP interface due to the adsorbed atomic hydrogen. Quantitative relationships between response magnitude and speed have been established. The Pt/InP MESFET also showed hydrogen induced current changes, and their magnitudes were much larger than those of the Schottky diode. Based on these, a novel structure of a nanometer-scale hexagonal hydrogen sensing head is proposed