1. Ch 6 – Tunnel Junctions and Applications of Tunneling EE 315/ECE 451 N ANOELECTRONICS I

2. O UTLINE  7.1 Coulomb Blockade  7.2 The Single-Electron Transistor  7.3 Other SET and FET Structures  7.4 Main Points 11/1/2010 2 R.M UNDEN - F AIRFIELD U NIV. - EE315

3. 7.1 C OULOMB B LOCKADE 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 3

4. C APACITOR P ROPERTIES 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 4

5. 7.1.1 N ANOCAPACITOR 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 5 Tunnel one electron Classical Model of Capacitance This leads to:

6. C OULOMB B LOCKADE IN N ANOCAPACITOR 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 6 So, Energetically, We only notice the Blockade effect for very small capacitors And temperature plays a role k b = 86 μeV/K -> k b T @ RT ~ 25 meV @ 293K For || C, let d = L/10 C or T must be very small!

7. T UNNEL J UNCTIONS 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 7

8. T EMPERATURE D EPENDENCE 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 8

9. T EMPERATURE D EPENDENCE OF N ANOPARTICLE C LUSTERS 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 9

10. 7.1.2 T UNNEL J UNCTIONS 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 10 Rt represents the ability of the electron to tunnel (the distance between the plates), while C is the capacitor that we are charging up. Rt cannot be too large, therefore, simply increasing d to decrease C does not make Coulomb Blockade a visible effect Uncertainty: Generally R>>Ro ~ 26kOhms

11. 7.1.3 T UNNEL J UNCTION E XCITED BY C URRENT S OURCE 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 11 Classically: But when we allow tunneling: Hard to achieve experimentally

12. 7.1.4 Q UANTUM D OT C IRCUITS 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 12 Using to TJ to achieve a small quantum dot (QD), or island, between them makes it easier to control the behavior. Where electron tunneling allows nq electrons to accumulate on the island

13. QD S TORED E NERGY 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 13

14. QD T UNNELING E VENT 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 14

15. QD E NERGY B AND D IAGRAMS 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 15

16. E NERGY B ANDS (2) 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 16

17. E NERGY B ANDS (3) 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 17

18. E NERGY B ANDS (4) 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 18

19. C OULOMB S TAIRCASE 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 19 Tunneling Occurs @:

20. STM C OULOMB S TAIRCASE 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 20

21. 7.2 S INGLE -E LECTRON T RANSISTOR 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 21

22. SET E NERGY D IAGRAM 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 22

23. C OULOMB D IAMONDS 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 23 Use the gate to adjust the potential on the island Tunneling occurs when both conditions are met. Tunneling Onto the islandTunneling Off the island

24. C OULOMB D IAMONDS 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 24

25. G ATE V OLTAGE C ONTROL FOR T RANSISTOR E FFECT 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 25 For very small C the effect is visible at Room Temp.

26. 7.2.1 SET L OGIC 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 26

27. SET INVERTER 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 27

28. SET L OGIC 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 28

29. 7.3 SET & FET S TRUCTURES 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 29

30. 7.3.1 CNT FET S AND SET S 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 30

31. CNT FET P ROPERTIES 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 31

32. 7.3.2 S EMICONDUCTOR N ANOWIRE FET S 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 32

33. S EMICONDUCTING NW SET 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 33

34. 7.3.3 M OLECULAR SET S AND M OLECULAR E LECTRONICS 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 34

35. M OLECULAR RTD AND SET 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 35

36. M AIN P OINTS 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 36  the Coulomb blockade effect  current-biased tunnel junctions  the influence of capacitance and energy on tunneling and Coulomb blockade  basic Coulomb blockade structures  tunnel junction models, tunneling in quantum dot circuits, and the Coulomb Diamond  the SET and its applications  electronic channels based on carbon nanotubes and semiconducting nanowires  the basic idea of molecular electronics

37. 7.5 P ROBLEMS 11/1/2010 R.M UNDEN - F AIRFIELD U NIV. - EE315 37