A PATTERNED GATE ARCHITECTURE FOR THE STUDY OF HIGH-QUALITY ALGAAS GAAS SYSTEMS IN THE EXTREME QUANTUM LIMIT/

The success of Schottky gates in defining patterns in the two-dimensio nal electron system (2DES) of AlGaAs/GaAs heterostructures has general ly been limited to 2DESS located within 150 nm of the semiconductor su rface. We describe the fabrication and use of an insulated gate archit ecture which reduces gate leakage currents for the higher biases requi red to define patterns in a 2DES located up to 700 nm below the semico nductor surface. This architecture is important for periodic gate patt erns which extend over macroscopic distances, where the increased leak age current through Schottky gates can severely limit the range of the gate bias. We report photoluminescence spectra obtained while biasing a grid-patterned insulated gate defined over a 1.6 mm by 1.6 mm area and above a low-electron-density, high-electron-mobility heterostructu re. This is the first report of a patterned gate architecture suitable for optical and transport studies of the effect of controlled periodi city on a high-quality 2DES and its low-temperature ground states in a magnetic field, in particular the magnetically induced Wigner solid.