Piezoresistance in Strained Silicon and Strained Silicon Germanium

ABSTRACTThis paper presents experimental results of the piezoresistance in p-type tensile strained silicon and compressive strained silicon germanium grown by molecular beam epitaxy (MBE) on (001) silicon substrates. The piezoresistance decreases in a tensile strained layer and increases in a compressive strained layer when compared to the unstrained material. The results show that one can tune the piezoresistance by tuning the strain in the piezoresistor and thus tailor the performance of the device. The obtained results show an increase in the piezoresistance effect of 35% in compressive strained silicon germanium and a decrease in the piezoresistance effect in tensile strained silicon of 24%. Furthermore, the results show that the piezoresistance of a tensile strained silicon crystal has a smaller temperature dependency compared to that of unstrained silicon. The piezoresistance effect decreases by 7% in tensile strained silicon compared to the piezoresistance effect decrease in silicon of 18% when changing the temperature from 30°C to 80°C.</jats:p