Synthesis and properties of hydrogenated aluminum thin film by reactive sputtering

Abstract

The synthesis procedure of a thin aluminum-hydrogen film on a silicon substrate is described and its result thoroughly investigated by a number of experimental methods. The reactive sputtering deposition was carried out to obtain a structure containing aluminum hydride. The resulting film has characteristic non-metallic properties, though according to thermal desorption studies its hydrogen content is close to AlH1.1, which is lower than stoichiometric aluminum hydride AlH3. Thermal desorption of hydrogen differs significantly from that of AlH3 powder as it has not one but several peaks. According to transmission electron microscopy the film is mostly amorphous but contains crystalline phase. Our interpretation of the experimental data suggests that some hydride phase microcrystals were formed as the film was deposited, but most hydrogen was stored inside the film without forming a crystalline structure in both bounded and unbounded states. The luminescent properties of the synthesized film are similar to aluminum hydride, and it can be concluded that the amorphous Al-H structure of the synthesized film shows resemblance with AlH3 crystals populated with hydrogen vacancies.