Exploration of Electron Glass

Electron-electron interactions suppress the density of states (DOS) near the Fermi level in both metals and insulators. For insulators this suppression (the Coulomb Gap) can persist for such long times it has been called the electron glass. 

We have studied MBE samples having a metal-insulator-semiconductor-metal geometry, in which the semiconductor is barely-insulating, compensated, p-type GaAs. Time-domain capacitance measurements showed the large metastable screening length in the semiconductor expected from a reduced DOS, but represent and average over a spatially varying potential.