Hooge Mobility Fluctuations in n-InSb Magnetoresistors As a Reference for Access Resistance LF-Noise Measurements of SiGe Metamorphic HMOS FETs

For the first time, to verify the origin of LF-noise (LFN) in the access resistance of metamorphic SiGe HMOS FETs, we used a thin film n-InSb magnetoresistor (MR) as a reference control. Hybrid MRs were fabricated on NiO×Fe2O3 ferrite substrates from Sn-doped MBE-grown n-InSb/i-GaAs heterostructures. The thickness of the InSb epilayers lie in the range 1.0-2.0 µm giving a room-temperature Hall mobilities of µ = 5.5×104 cm2/Vs at a carrier densities of 5×1016 cm-3. The device resistance could be changed by up to 500% in a magnetic field of B=325 mT. LFN spectra were measured at B=0 and 31mT. Results show that the current dependence of the PSD for this MR is described by the Hooge mobility fluctuation model, according to S _I /I2 =S _R /R2 =a _H ×µ(eR / fL2). A simple design for a calibrated noise reference is proposed.