Influences of hydrogen passivation on NIR photodetection of n-type β-FeSi2/p-type Si heterojunction photodiodes fabricated by facing-targets direct-current sputtering

ABSTRACTHydrogen passivation was applied to the initial epitaxial growth of n-type β-FeSi2 thin films on p-type Si(111) substrates by facing-targets direct-current sputtering (FTDCS) in order to reduced the formation of interface states and terminate dangling bonds in the β-FeSi2 films, and the passivation effects were studied on basis of the electrical evaluation results of the formed n-type β-FeSi2/p-type Si heterojunction photodiodes. The initial growth was made at different gas inflow H2/Ar ratios ranging from 0 to 0.2. The photodetection performance of the photodiode fabricated at the ratio of 0.2 was markedly improved as compared to those of the other samples. The quantum efficiency and detectivity were 2.08 % and 1.75 × 1010 cm√Hz/W, respectively. The sample exhibited the minimum junction capacitance density of 9.2 nF/cm2. The enhanced photodetective performance should be mainly because dangling bonds that act as trap centers for photocarriers are effectively inactivated by the passivation.