Conduction Threshold, Switching, and Hysteresis in Quantum Dot Arrays

We investigate low temperature transport in 200×200 arrays of GaAs quantum dots in which coupling between dots and electron density is controlled by a single gate. Current-voltage curves obey a power law above a threshold voltage with exponent ~1.5, and show discontinuous and hysteretic jumps in the current, or ``switching events.'' Multiple switching events result in a hierarchy of hysteresis loops. Switching and hysteresis decrease with increasing temperature and disappear above 1 K. A possible mechanism for the hysteresis involving gate-to-dot tunneling is discussed.