Observation of Negative Differential Resistance Jiasen Ma Supervisor: Philippe Guyot-Sionnest

1. Observation of Negative Differential ResistanceJiasen MaSupervisor: Philippe Guyot-Sionnest • Due to resonant tunneling the transmission coefficient gets some peaks and valleys. We expect the curve of the current which is proportional to it will drop as the voltage is increasing at some points.

2. Dithiol molecules help to form the two layers of QDs (TOPO Capped CdSe Dots).

3. Fabrication ofthe Device • An Au substrate of 100nm thickness is evaporated on the mica. • Immerse it immediately into Hexanedithiol solution and CdSe QD solution sequently at proper temperature. • The size of dots in the second layer can be chosen separately. • The sample should be rinsed with toluene and dried in nitrogen steam.

4. We are planning to use conducting AFM to measure the I-V curve. • Electrons in the electrode have different energy. This will expand the peaks. Also the thermal fluctuation. • Switches and memory cells may be constructed based on this property.

5. References • Tsu R. and Esaki L. Applied Physics Letters 22(11), 562-564, 1973 • N. C. Van der Yaart, et al, Physical Review Letters 74(23), 4702-4705, 1995 • M. Ouyang, et al, Science 301, 1074-1078, 2003 • M. A. Reed, et al, Applied Physics Letters 78(23), 3735-3737, 2001