1. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 1 Chapter IV June 14, 2015June 14, 2015June 14, 2015 P-n Junction

2. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 2 Fabrication of a p-n Junction

3. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 3

4. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 4 I-V curve of p-n Junction

5. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 5 Equilibrium Fermi Level

6. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 6

7. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 7

8. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 8

9. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 9

10. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 10

11. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 11

12. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 12 Should be positive with

13. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 13 Space Charge or Depletion Region

14. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 14

15. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 15 Abruption Junction

16. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 16

17. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 17

18. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 18

19. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 19

20. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 20

21. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 21

22. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 22

23. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 23

24. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 24

25. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 25 Linearly Graded Junction

26. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 26

27. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 27

28. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 28

29. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 29

30. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 30 Depletion Capacitance

31. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 31 Depletion Capacitance

32. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 32

33. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 33 Evaluation of Impurity Distribution

34. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 34

35. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 35

36. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 36 Current Voltage Characteristics for Ideal Diode

37. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 37 Current Voltage Characteristics Electron current flow

38. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 38

39. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 39

40. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 40

41. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 41

42. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 42 Fig. 17 Injected minority carrier distribution and electron and hole currents. (a) Forward bias. (b) Reverse bias. The figure illustrates idealized currents. For practical devices, the currents are not constant across the space charge layer.

43. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 43

44. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 44

45. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 45 Generation and Recombination and High Injection Effect

46. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 46 = n i /τ g

47. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 47

48. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 48 From continuity equation

49. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 49

50. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 50 η=1, diffusion current dominates, η=2, recombination current dominates. Series resistance or high injection condition, p n (x n )=n n.

51. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 51

52. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 52 Temperature Effect

53. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 53

54. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 54 Generation current dominates Diffusion current dominates

55. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 55 Charge Storage and Transient Behavior

56. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 56

57. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 57

58. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 58

59. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 59

60. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 60

61. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 61

62. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 62 Junction Breakdown under reverse bias 1. Tunneling Effect: it occurs only when the electric field is very high and is above 10 6 V/cm for Si or GaAs. The doping concentration for both p- and n-regions must be greater than 5x10 17 cm -3. The breakdown voltage is less than 4E g /q. 1. Tunneling Effect: it occurs only when the electric field is very high and is above 10 6 V/cm for Si or GaAs. The doping concentration for both p- and n-regions must be greater than 5x10 17 cm -3. The breakdown voltage is less than 4E g /q. 2. Avalanche Multiplication: for p + -n one sided abrupt junction, the doping concentration of N D is less than 10 17 cm -3 and the breakdown voltage is greater than 6E g /q. 2. Avalanche Multiplication: for p + -n one sided abrupt junction, the doping concentration of N D is less than 10 17 cm -3 and the breakdown voltage is greater than 6E g /q.

63. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 63

64. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 64 A multiplication factor M n is defined as

65. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 65

66. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 66 The number of electron-hole pairs generated by an electron per unit distance traveled is called the ionization rate of the electron, α n. The electron-hole pair generation rate G A is given by:

67. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 67 Using Eqs 19 and 21

68. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 68

69. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 69

70. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 70 For large a and low N B For small a and high N B

71. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 71

72. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 72

73. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 73

74. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 74 Heterojunction

75. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 75

76. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 76 Assume that there is a negligible number of traps or generation- recombination centers at the interface. This assumption is valid only for two semiconductors with closely matched lattice constants

77. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 77

78. Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 78