Optimizing the physical contribution to the sensitivity and signal to noise ratio of extraordinary magnetoresistance quantum well structures

Abstract

For applications to extraordinary magnetoresistance ͑EMR͒ quantum well sensor design, the electron areal density n 2D , the mobility , and the products n 3D 1/2 2 and n 3D 1/2 5/2 are key physical parameters to be optimized for enhanced device sensitivity and signal to noise ratio. We model the electron areal density and carrier mobility in a two-dimensional electron gas layer developed in a ␦-doped AlInSb/ InSb heterostructure. The nonparabolic band structure due to the nature of the small energy band gap of InSb is accounted for. The detailed description of the energy dispersion and the energy dependent effective mass are obtained by the k • P method of band structure calculation. The transport properties are calculated by including contributions of scattering from ionized impurities, the background neutral impurities, the deformation potential acoustic phonons, and the polar optical phonons. We calculate the dependencies of n 2D , , n 3D 1/2 2 , and n 3D 1/2 5/2 on temperature, spacer layer thickness, doping density, and the quantum well thickness. This has important implications for EMR sensor design.

Universal material trends in extraordinary magnetoresistive devices

“…This motivates the use of materials such as graphene and semiconductor 2-dimensional electron gases with low sheet carrier densities as the best-performing Hall and EMR sensors operating under fixed current bias. This is in contrast to previous studies which conclude that the signal-to-noise ratio scales as √ n in the thermal noise limited regime [32]. The discrepancy is caused by the authors not taking into account the inverse dependence of the sensitivity on the sheet carrier density found here.…”

“…3. Magnetic field sensors: When aiming to use EMR devices as magnetometers, the appropriate figure of merit is the noise-equivalent field [19,32], which describes the detection limit defined as the magnetic field resulting in a signal-to-noise ratio of 1. If the EMR sensor is limited by thermal noise and operated at a constant current, the noise-equivalent field (B NEF ) when measuring small magnetic field signals in a background or bias magnetic field (B b ) is:…”

“…The material requirements sparked an interest in studying the behavior of EMR in various high-mobility materials, including InSb [8,[12][13][14][15][16][17], InAs [18][19][20], GaAs [21][22][23][24] and graphene [25][26][27][28][29][30]. Beyond investigating different material platforms and material parameters, there has also been a strong interest in exploring various EMR geometries [2,[31][32][33][34][35][36][37][38][39][40][41]. Four of the key geometries explored for EMR are displayed in figure 2, which include the concentric circular devices, bar-shaped devices, the asymmetric off-center circular devices and more exotic multi-branched devices.…”

Limiting scattering processes in high-mobility InSb quantum wells grown on GaSb buffer systems

“…The intrinsic material parameters used for this work are [67,68] Table II. The depletion plane is d = 30 nm away from the w 0 = 23 nm QW and we estimate the density to be n d = 4.41 × 10 12 cm −2 .…”

“…The intrinsic material parameters used for this work are [67,68] s = 16.52, ∞ = 15.7, ρ d = 5790 kg/m 3 , v s = 3700 m/s, and hω 0 = 25 meV. Furthermore, with the effective mass m * = 0.0254 m e retrieved from cyclotron resonance measurements (see Appendix), a * B = 35 nm and q TF = 0.057 nm −1 .…”