New hydrogen sensor using a polycrystalline diamond-based Schottky diode

A new hydrogen sensor utilizing plasma-enhanced chemical vapor deposited iamond in conjunction with palladium (Pd) metal has been developed. The device is fabricated in a layered Pd/undoped iamond/p-doped diamond Schottky diode configuration. Hydrogen sensing characteristics of the device have been examined in terms of sensitivity, linearity, response rate, and response time as a function of temperature and hydrogen partial pressure. Hydrogen adsorption activa-tion energy is investigated in the temperature ange from 27 to 85 ~ Analysis of the steady-state r action kinetics using the I-V method confirm that the hydrogen adsorption process is responsible for the barrier height change in the diamond Schottky diode. The ability to fabricate diamond-based hydrogen sensor on a variety of substrates makes the device very versatile for gas sensing. The recent advances in the plasma-enhanced chemical vapor deposition (PECVD) process has resulted in the real-ization of high quality polycrystalline diamond films for device applications. Microelectronic devices and sensors such as Schottky diodes, field effect transistors (FETs), thermistors, and pressure sensors ~-4 have been fabricate