High sensing response Pd/GaN hydrogen sensors with a porous-like mixture of Pd and SiO_2

摘要

A metal-semiconductor-metal Pd/GaN hydrogen sensor with a porous-like mixture of Pd and SiO_2 is investigated. Besides symmetrically bidirectional sensing characteristics with a widespread voltage regime (at least-5-5 V), a high sensing response of 8 × 10~5 (7.7 × 10~6) corresponding to a Schottky barrier height variation of 352 (411) meV is obtained in a 4890 ppm H_2/N_2 ambience at a voltage of -1.5 (-5) V. A highly efficient dissociation of hydrogen molecules due to an enhanced catalytic activity of the mixture explains the improved performance. Furthermore, dynamic responses by alternately switching voltage polarity and introducing and removing hydrogen-containing gases are also included to evaluate the proposed device as a high sensing response and low power sensor.