Transport and noise in 90nm n-GaAs Epilayers

Extraordinary Magnetoresistance (EMR) belongs to the family of EXX effects which form the basis for a number of devices that offer the potential for high sensitivity applications. Such devices would benefit from minimising the active volume of the sensor. To reduce that volume and minimize wafer fabrication complexity it is desirable to employ unltra-thin GaAs epilayers. Accordingly, we report here the transport and noise properties of 90nm Si-doped GaAs films grown by molecular beam epitaxy which have been fabricated into both microscopic EMR devices and macroscopic van der Pauw geometries. These films exhibit a room temperature electron mobility and density of 3225 $cm^2V^{-1}s^{-1}$ and1.45x$10^{17}cm^{-3}$, respectively, and show only a 6\% variation over the temperature range $2K