Electronic bistability in electrochemically self-assembled quantum dots: A potential nonvolatile random access memory

An electronic bistability has been observed in a two-dimensional spatially ordered array of 10 nm quantum dots self-assembled by electrodepositing CdS in nanoporous anodic alumite film. The current-voltage characteristic of the array shows switching between two stable conductance states, which can be controlled by an external bias. The bistability is observed when current flows laterally between two contacts on the top surface of the array, and also when current flows vertically between a top contact and the bottom (conducting) substrate. If the system is left in one conductance state, it remains there for at least 180 h and possibly much longer, until switched to the other state by an external bias. Such an effect may find applications in inexpensive, ultradense nonvolatile static random access memory. (C) 2000 American Institute of Physics. [S0003- 6951(00)02904-1].