Three-point probe 1/f noise measurement

Abstract

Abstract The impact of contact resistance (R c) on 1/f noise measurements was studied to demonstrate improved accuracy with a novel three-point probe (3pp) method, introduced here, versus the typical two-point probe (2pp) arrangement. It was shown for n+ -Si that using indium to lower R c decreased the noise spectral density (NSD) over 100× for 2pp. In the 3pp configuration, NSD was reduced by another ∼5×, independent of indium use (i.e. spectra overlapped), suggesting that 3pp avoids the impact of R c on NSD. More heavily doped n++ -Si also showed improvements with 3pp and 2pp/indium versus 2pp/bare. Expectedly, 3pp provided less of a benefit relative to 2pp/indium as R c was already small due to highly degenerate doping. Measurement drift also improved with 3pp. These results have implications on 1/f measurement accuracy for the broadly used 2pp arrangement. The 3pp method provides a better noise floor for NSD testing because it is not convoluted with signal from R c, does not require metallization and has improved simplicity and versatility yet performs equal to four-point probe methods.