Highly sensitive split-contact magnetoresistor with AlAs/GaAs superlattice structures

A class of split-contact magnetoresistors made of a modulation-doped AlAs/GaAs superlattice grown on a semi-insulating GaAs substrate is reported. Their design geometry is reminiscent of the split-drain MAGFET, but their active sensor layer is the two-dimensional electron gas at the AlAs/GaAs heterojunction. A linear response of the relative current imbalance with high sensitivity is obtained below 1-T magnetic induction. Sensitivity is found to be as high as 46%/T for the preferable device geometry with a length-to-width ratio of 2 and split-contact separation-to-width ratio of 0.05, an order of magnitude higher than that of comparable MAGFET designs, The I/O efficiency of signal transformation is very large at small magnetic induction compared to that of conventional magnetoresistors. A simple formula for the sensitivity as a function of Hall mobility and geometry (length, width, and split-contact separation) is derived