Comparative Study of Pd Modified ZnO/p-Si and ZnO/PS/p-Si Hetero Structure for Hydrogen Detection

摘要

Nanoporous ZnO was prepared by the simple low cost sol-gel method and was deposited both on crystalline Si and nano crystalline porous silicon substrate. To passivate the defect states (arise due to the nano structure of the ZnO thin film and introduce a barrier for the current conduction) and to improve the gas sensitivity the nano crystalline ZnO surfaces were modified by PdCl_2 solution. Both unmodified and the Pd modified sensors having Pd-Ag (26%)/ZnO/p-Si/Al and Pd-Ag (26%)/ZnO/PS/p-Si/Al device structures were investigated in different hydrogen concentrations (0.01, 0.05, 0.1, 0.5 and 1.0%) regarding optimum biasing voltage and temperature. Both the sensor showed improved performance in terms of operating temperature, response magnitude, response time and recovery time after the modification treatment.