Electrical performance in iron-passivated porous silicon film

The electrical properties in iron-passivated porous silicon (PS:Fe) with stable optical properties were studied. Iron is incorporated in porous silicon (PS) by impregnation method using Fe(NO3)3 aqueous solution. Energy dispersive X-ray analysis and Raman scattering revealed the presence of iron atoms over most of the PS layer surface. We discussed the current–voltage (I–V) of PS and PS:Fe structures under both forward and reverse bias conditions. The I–V measurements obtained on PS:Fe showed a rectifying effect and an improvement of both the threshold voltage and current intensity as compared with those relative to PS. By using the Richardson–Schottky diode equation and taking into account a series resistance (RS), all the parameters of the structures are determined and discussed. The presence of the iron in the PS matrix reduces the value of ideality factor n (close to 2) and the series resistance. At low voltage, the PS:Fe produces an important change in the transport mechanism of the PS; from ohmic to space charge limited conduction (SCLC) mechanism. The obtained results indicate the presence of the shallow acceptor levels in the gap due to the iron, allowing us to propose a band-gap diagram of Ag/PS:Fe/c-Si.