  Telegraphic noise is one of the most significant problems that arises when
making sensitive measurements with lateral electrostatic devices. In this paper
we demonstrate that a wafer which had only produced devices with significant
telegraph noise problems can be made to produce 'quiet' devices if a thin
insulator layer is placed between the gates and the GaAs/AlGaAs
heterostructure. A slow drift in the resulting devices is attributed to the
trapping of charges within the specific insulator used. This charge can be
manipulated, leading to strategies for stabilizing the device.
