Sub-100-nm negative bend resistance ballistic sensors for high spatial resolution magnetic field detection

Researchers from the London Centre for Nanotechnology at Imperial College report the magnetic field detection properties of ballistic sensors utilizing the negative bend resistance of InSb/In1-xAlxSb quantum well cross junctions as a function of temperature and geometric size. The researchers demonstrate that the maximum responsivity to magnetic field and its linearity increase as the critical device dimension is reduced. This observation deviates from the predictions of the classical billiard ball model unless significant diffuse boundary scattering is included. The smallest device studied has an active sensor area of 35 x 35 nm(2), with a maximum responsivity of 20 k Omega/T, and a noise-equivalent field of 0.87 mu T/root Hz at 100 K.

 Full article: http://apl.aip.org/resource/1/applab/v98/i6/p062106_s1

Figure:  (a) Scanning electron microscopy micrograph of a w = 400 nm cross and lead configuration. Residual polymer/resist is present on the mesa edge. The dashed area indicates the mesa sidewall, shown close up with a 2× magnification in (b). (c) AFM scan of etched surface with rms Δ = 3.8 nm. The z-scale is 32 nm. (d) A line scan taken across the AFM as indicated in (c), illustrating the typical surface profile.(a) Scanning electron microscopy micrograph of a w = 400 nm cross and lead configuration. Residual polymer/resist is present on the mesa edge. The dashed area indicates the mesa sidewall, shown close up with a 2× magnification in (b). (c) AFM scan of etched surface with rms Δ = 3.8 nm. The z-scale is 32 nm. (d) A line scan taken across the AFM as indicated in (c), illustrating the typical surface profile.

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