In-plane uniaxial stress effects of AlGaAs/GaAs modulation doped heterostructures characterized by the transmission line method

Transmission line method patterns were fabricated on AlGaAs/GaAs heterostructures to measure the effect of uniaxial stress on the heterojunction two-dimensional electron gas resistivity and the contact resistance. Uniaxial compressive stress was applied in the [110] and [11̄0] directions of heterojunctions fabricated on (001)-oriented GaAs substrates. Fitting the measured data to a lumped resistor model yielded normalized sheet resistivity stress coefficients of −3.2%/kbar and 12.6%/kbar for stress in the [110] and [11̄0] directions, respectively. From these coefficients we obtain a value for the piezoelectric constant e14 of Al0.4Ga0.6As to be −0.26 C/m2, which when linearly extrapolated to AlAs gives −0.40 C/m2 compared to the value −0.225 C/m2 calculated by Hübner [Phys. Status Solidi B 57, 627 (1973)].