Study of carrier transport in metal/porous silicon/Si structures

Electrical contacts to porous silicon were formed by depositing various metals such as aluminum, gold, and titanium onto its surface. Low temperature current–voltage measurements were performed, which allowed us to identify the contact as a metal–insulator–semiconductor (MIS) structure. The parameters which characterize the MIS structure: the mean barrier height presented by the insulating film (χ), the barrier height presented to the electrons in the metal by the semiconductor itself (VB0), the ideality coefficient (n) and the series resistance (Rs), were determined for each type of contact studied. All of these contacts show fairly high values of the ideality coefficient, which are explained by the presence of a large concentration of interface states.