Charge carrier transport in thermally oxidized metal/PS/p-Si and metal/PS/n-Si structures
Metal/PS/c-Si structures with porous silicon (PS) layers of 55?75% porosity were fabricated on moderately doped p- and n-type c-Si substrates and were thermally oxidized at 400?960 ?C. We studied the effect of oxidation on the charge carrier transport in these structures. It was demonstrated that trap-filled space charge limited current (SCLC) is the dominant transport mechanism at large forward bias. The analysis of the current?voltage characteristics in the SCLC region allowed us to determine the oxidation dependence of the effective thickness deff of the trap-rich tissue isthmuses, in which space charge is mostly accumulated. The exponential deff-dependence of the conductance in the ohmic region observed at low bias is explained by carrier tunnelling through potential barriers formed by SiOX isthmuses between silicon crystallites. The results can be used for fabrication of electronic devices based on oxidized PS and similar materials.