Electrical response of Pd/AlN/6H - SiC and Pd/AlN/3C - SiC devices to hydrogen gas: The effects of AlN layer

Abstract

The electrical response characteristics of PdAlN6H-SiC and PdAlN3C-SiC devices to hydrogen gas have been investigated. An AlN film, with a thickness of 100 nm, was deposited simultaneously on 6H-SiC (0001) and 3C-SiC (001) substrates. The structural, morphological, and microstructural characterizations of these devices were carried out using x-ray diffraction, atomic force microscopy, and transmission electron microscopy techniques. In both the cases, the AlN film showed a highly textured c axis growth with a wurtzite crystal structure. However, the surface roughness of the AlN film on 3C-SiC was larger by a factor of three compared to that deposited on 6H-SiC, with an associated increase in the value of dielectric constant of AlN. Theoretical analysis of the electrical characteristics suggests that, in addition to the physical properties of the semiconducting layer, the dielectric constant of AlN layer directly influences the electrical response of the device to hydrogen. The PdAlN3C-SiC device showed a consistently reduced electrical response to hydrogen compared to the PdAlN6H-SiC device. © 2007 American Institute of Physics.