C MOS-based devices have been at the heart of the technological advances in the microelectronics and computer industries. One particularly interesting approach, molecular tunneling devices, implements processes familiar to silicon device process engineers. Based on molecular switches, researchers at Hewlett Packard Labs and the University of California, Los Angeles, have developed logic gates and memory elements that fit between the wires used to address them. When a voltage is applied across the electrodes, current flows by resonant tunneling through the molecular electronic states. Rotaxanes provided the first two, but not reversibility.
Work is underway to identify and synthesize molecules that embody all three characteristics.
The manufacturability of these devices is a clear advantage. Processed on any flat substrate such as silicon, an insulating layer is deposited on top. A molecular monolayer is then deposited over the entire wafer using the Langmuir- Blodgett process. The wafer is submerged in a trough of water with the molecules afloat. Upon removal, a dense, uniform film of molecules coats the wafer.