Piezoelectric effects in GaAs FET's and their role in orientation-dependent device characteristics

Elastic stresses are frequently induced in GaAs substrates during the fabrication of FET's, particulariy in the vicinity of windows in dielectric overlayers. It is shown here that these stresses can produce piezoelectric charge densities of such magnitude to appreciably shift the pinchoff voltage and saturation current of FET's. These shifts are of opposite sign for FET's oriented along [011] and [011] directions on