Evaluation of the piezoresistive and electrical properties of polycrystalline silicon-germanium for MEMS sensor applications

This paper reports for the first time the experimentally evaluated piezoresistive properties of boron-doped poly-SiGe for different doping doses (from 2·10¹³ cm^-2 to 4·10¹⁵ cm^-2) and germanium content (49% and 64%). The resistivity and temperature coefficient of resistance are also studied. Results show that with proper tuning of the boron and germanium content, a gauge factor over 20 and a TCR as low as 0 are achievable. Finally, finite-element simulations of a possible application to a pressure sensor lead to sensitivities above 40 mV/V/bar, highlighting the potential of this material for MEMS piezoresistive sensor applications.