P type porous silicon resistivity and carrier transport

The resistivity of p type porous silicon (PS) is reported on a wide range of PS physical properties. Al/PS/Si/Al structures were used and a rigorous experimental protocol was followed. The PS porosity (P-%) was found to be the major contributor to the PS resistivity (rho(PS)). rho(PS) increases exponentially with P-%. Values of rho(PS) as high as 1 x 10(9) Omega cm at room temperature were obtained once P-% exceeds 60%. rho(PS) was found to be thermally activated, in particular, when the temperature increases from 30 to 200 degrees C, a decrease of three decades is observed on rho(PS). Based on these results, it was also possible to deduce the carrier transport mechanisms in PS. For P-% lower than 45%, the conduction occurs through band tails and deep levels in the tissue surrounding the crystallites. When P-% overpasses 45%, electrons at energy levels close to the Fermi level allow a hopping conduction from crystallite to crystallite to appear. This study confirms the potential of PS as an insulating material for applications such as power electronic devices. (C) 2015 AIP Publishing LLC.