Capacitance measurements of the dynamics of screening in the electron glass.

Electron-electron repulsion in disordered insulators causes a suppression of the effective Density Of States (DOS) known as the Coulomb gap. Capacitance measurements on specially designed structures provide a direct monitor of the evolution of the DOS with time. Our measurements in a compensated p-type GaAs structure have shown that the relaxation becomes slow at low temperatures, and the failure to return to equilibrium is similar to that in a spin glass.