Nanoscale Quantum Physics Group

Research - Project Four

Bistability in Scanning Tunneling Spectroscopy of Ga-Terminate Si (111)

Bistable electron transport, a phenomenon usualyl associate with double-barrier sturctures has been observed with a conventional STM junction formed between a metal tip and a Ga-terminate Si(111) surface at 77K. Large hysteresis loops appear in teh current-voltage characteristics when electrons are injected from the tip to the surgace. The turn-on bias varies from -3.1 to -4.0 V and shows an inverse dependence on the tip-sample distance, indicating a stong field effect. The turn-off bisas, however, is essentially pinned at a conductance threshold of -2.7V.