A comparative study of hydrogen sensing performances between electroless plated and thermal evaporated Pd/InP Schottky diodes

In this paper, we study and compare the hydrogen sensing performances of Pd/InP Schottky diode sensors fabricated by electroless plating and thermal evaporation. Experimental results show that the used electroless plated Schottky diode exhibits superior detection sensitivity on hydrogen with a wider detection range and lower detection limit. The Schottky barrier height change DeltaPhi(Bn) and the ideality factor n are increased with the increase of hydrogen concentration. Under a hydrogen concentration about 5000 ppm H-2/air, DeltaPhi(Bn) and n reach their saturation values. Compared with the thermal evaporated diode, the performances of larger maximum barrier height lowering and nearer unity ideality factor are observed in the Schottky diode fabricated by electroless plating. It is comprehensible that more charge states are created at the electroless plated Pd/InP interface, which allows the adsorption of more hydrogen atoms and results in superior sensing performances.