1. Single-electron Devices Speaker: Qiaoyan Yu qiaoyan@ece.rochester.edu ECE423 12-16-2006

2. 2 Agenda  Milestone  Motivations  New characteristics  Single-electron transistor (SET)  Challenges  Conclusions

3. 3 Milestone  In 1909, Millikan first illustrated the manipulation of single electrons.  In 1985, Dmitri Averin & Konstantin Likharev proposed single-electron transistor.  In 1987, Theodore Fulton & Gerald Doald at Bell lab fabricated and demonstrated SET.

4. 4 Motivation  Power consumption challenges high performance and high density chip design Faster and more information processing resulting in generating more heat flux  Reduce the corresponding charge per bit! Single-electron Device!!!

5. 5 SED new characteristics  Exploit the quantum effect of tunneling Control and measure the movement of single electron  Charge doest not flow continuously Instead in a quantized way  Extremely high charge sensitivity High precise for charge measurement

6. 6 Single-electron transistor (SET)  Architecture  Equivalent circuit  Operation principle  I-V curve  SET VS. MOSFET

7. 7 Architecture gate CgCg VgVg VbVb SourceDrain Tunnel junctions island C1C1 C2C2 +q1-q1 +q2-q2 q V2V2 V1V1

8. 8 Equivalent circuit

9. 9 Operation principle

10. 10 Operation principle

11. 11 Operation principle

12. 12 I-V curve

13. 13 SET vs. MOSFET  Structure Two tunneling barrier vs. inversion channel  Size Extremely small vs. large (although scaled down)  Main physical principle Coulomb blockade vs. electron diffusion  Threshold voltage & source-drain current Periodic vs. not periodic  Sensitivity High vs. low (10000X)  Power Low vs. high

14. 14 SED challenges  Difficult to precisely control the device implementation  Characteristic of the device varies significantly from location to location  Suffer from “offset charges” Randomly fluctuation of control signal

15. 15 Conclusions  Because of natural small dimension, SED is a potential solution for continue silicon scaling.  It is not clear that SET replaces FET.  It is certain that quantum properties of electrons will be crucial in the design of electron devices.  Electron beam lithography and scanning probe techniques offer the best prospects for the future.  Some more esoteric techniques based on atomic particle deposition and colloid chemistry may also provide some benefits.

16. 16 The End Thank You! Any questions?