Effect of Etching Time to Tune Magnetoresistance Between Positive and Negative Values in p-Type Silicon Nanowires

Silicon nanowires (SiNWs) are formed by metal-assisted chemical etching of crystalline p-type silicon, in a mixture of aqueous HF and AgNO3 chemical solutions. The magnetic field effects on the current of Ag/SiNWs/Si/Al structures have been studied. At room temperature, magnetoresistance (MR) measurements revealed positive and negative MR depending on the etching time and on the applied voltage. Huge positive MR of about 1200% has been observed at the low field. The negative MR is attributed to the weak localization effect, while the positive one is related to the ohmic regime, where holes control the current. The MR effect depends on the applied voltage and on the SiNWs length. The huge MR effect on SiNWs can be exploited in magnetic-field sensor devices.