Boron-Doped Si[sub 0.8]Ge[sub 0.2] Thin Film Deposited by Helicon Sputtering for Microthermoelectric Hydrogen Sensor

A boron-doped thin film of thickness was deposited by helicon sputtering. Thermal annealing was carried out to crystallize as-deposited amorphous-like thin films. The thermoelectric properties of the films, such as an electrical conductivity, a carrier concentration, a mobility, and a Seebeck coefficient, were investigated. As a result, the films by helicon sputtering exhibited finer grains and smoother surface than those of the film deposited by conventional radio frequency (rf) sputtering. The film deposited by helicon sputtering with an rf induction coil power of and annealed at for showed a resistivity of , a Seebeck coefficient of , a Hall mobility of , and a carrier concentration of at . A microthermoelectric hydrogen sensor (micro-THS) with the boron-doped thin film and annealed at for showed high sensitivity for hydrogen gas in air. This sensor could have wide detection range of hydrogen concentration from to 3%. At an operating temperature of , for the low hydrogen concentration of , clear response was shown by the micro-THS with the film deposited by helicon sputtering and annealed at for .