The sub-micrometer thickness n-InSb/i-GaAs epilayers for magnetoresistor applications at room temperatures of operation

Magnetotransport at fields up to View the MathML source and LF-noise characteristics are reported for miniature magnetoresistors with ferrite concentrators based on Sn-doped n-InSb/i-GaAs heterostructures grown by MBE. The thickness of the InSb epilayers lie in the range 0.55–View the MathML source giving room temperature mobilities of 2.5–View the MathML source with carrier densities of (0.5–View the MathML source. The room temperature magnetoresistance (MR) for our two terminal devices could be as high as 115% at View the MathML source which is comparable to the extraordinary MR (ExMR) recently reported in microscopic composite van der Pauw disks four terminal devices [Science 289 (2000) 1530]. In addition, a high signal-to-noise ratio and a good temperature stability of R(B)/R0=0.5–View the MathML source was observed for View the MathML source (below the saturation field Bsat for ferrite). Device resistance stability R0(T) was equal to 0.27–View the MathML source in zero field with a nominal device resistance R0=197–View the MathML source for DC currents in the range I=0.01–View the MathML source. The minimum detectable magnetic field is estimated from the reduced differential MR (View the MathML source at View the MathML source and normalised 1/f current noise power spectral density measured at the same field. The resolution limit View the MathML source at View the MathML source and View the MathML source at View the MathML source. These resolution limits are seven times better than those recently reported for the same material n-InSb/i-GaAs and ferrite fabricated Hall sensors [Magnetotransport and Raman characterization of n-InSb/i-GaAs epilayers, for Hall sensors applications over extremely wide ranges of temperature and magnetic field, Proceedings NGS 10, IPAP Conference Series 2, IPAP, Tokyo, 2001, pp. 151–154].