Effect of porosity on the enhancement of relative magnetoconductance in porous Si nanostructures: a comparative study with Si nanowires

We reported a comparative study of relative magnetoconductance (RMC) effect between porous silicon nanostructures (PSiNs) and silicon nanowires (SiNWs). We investigated the correlation between the RMC and the porosity in PSiNs produced by an electrochemical etching process in HF-based solutions. The experimental results exhibit a positive RMC in PSiNs which depends heavily on the porosity. The RMC effect passes from 0.09 to 2.2% for porosities ranging from 32 to 55% at low static magnetic field of 0.5 T at room temperature. SiNWs samples were formed by metal-assisted chemical etching method of crystalline silicon in AgNO3-based chemical solutions. Scanning electron microscopy shows that the SiNWs may have different structures depending on the etching time. Comparatively to PSiNs, the observed positive RMC was enhanced in SiNWs, and this effect is important and reached 9% at a magnetic field of 0.5 T. Weak localization (WL) theory was used to explain the observed positive RMC and to determine the phase coherence length L-phi. We found that WL effect can be observed at room temperature on inhomogeneous nanostructured thin films and the L-phi length depends heavily on the porosity effect in PSiNs.