1. Semiconductors
Chapters

2. Tubes

3. Semiconductors

4. Silicon Atom

5. Germanium Atom (Less abundant than Silicon!!)

6. Intrinsic Material
Pure Substance
No Impurities!

7. Negative Temperature Coefficient
Silicon
Low Temperature – Poor Conductor
High Temperature – Good Conductor
Negative Temperature Coefficient
Temperature Increases – Resistance Decreases

8. Covalent
Bond
Share 2e-
Silicon Si Si Si Si Si Si Si Si Si Si Si Si

9. Doped Material – N-Type (electrons – majority carrier)As Si Si Si e- Si As Si Si e- Si Si As Si

10. Doped Material – P-Type (holes – majority carrier)Si Si Ga Si + Si Si Si Ga
HOLE + Si Si Ga Si
HOLE +

11. N - Material e- e- e- e- e- e- e- e- e- e- e-

12. P Material + + e- + + + e- + + + e- e- e- e-

13. N Type: Negative Charge (-)
P – N Type Material
N Type: Negative Charge (-)
P Type: Positive Charge (+)

14. Advantages of Semiconductors
Smaller
Low Power
Cheaper
High Efficiency
Great Reliability
Runs Cooler
More Rugged
Long Life
Hazardous Environment
Economic Production
Less Noisy
Made Part of an I.C.
(Integrated Circuit)

15. Disadvantages of Semiconductors
Susceptible to Temperature Changes.
Extra components for Stabilization.
Easily Damaged
Exceeding Power Limits
Reversing Polarity
Excess Heat when Soldering

16. The PN Junction

17. An area that has no majority carriers.
P-N Junction P N e- + {
Depletion Region
An area that has no majority carriers.

18. P N { + e- e- + + e- + e- e- + e- + + e- P-N Junction Barrier Voltage
Build up of charge for each side.
Must be overcome to conduct.

19. - + e- + e- e- + + e- + e- e- e- + e- + Diode Operation
Bias Voltage
Reversed Bias (No Current Flow)
There is a small Leakage Current that can flow!!!

20. - + + e- + e- + e- e- e- e- e- + e- + e- + e- + e- + e- + e- +
Diode Operation + e- + e- + e- e- e- e- e- + e- - + e- + + e- + e- + e- + e- +
Once the barrier voltage is exceeded!!
Forward Bias (Current Flows)

21. Forward Biased Diode EF is the Forward Voltage on the Diode
EF for Germanium is 0.3V
EF for Silicon is 0.7V

22. Example: What is the Forward Biased Current (IF)? Germanium Diode+
EF= 0.3V
R = 10kΩ
Es= 9V
IF= ER R
ES - EF R =
9V - 0.3V
10kΩ =
0.87mA =

23. Diode Operation – Forward Biased+ - +

24. Current e- + - +

25. Manufacturers Specifications
Maximum Forward Current
Maximum Reverse Voltage

26. One Directions!!!

27. Diode Symbol P N
Anode
Cathode

28. Diode
Current Flow
Anode
Cathode

29. Diode Identification
White or Silver
Line on Anode
Anode
Cathode

30. Diode Construction
Grown Junction
Alloyed Junction
Diffused Junction
(Most Common)

31. Diode Testing
Low
Resistance
High
Resistance

32. LED – Light Emitting Diodes

34. LED – Light Emitting Diodes

36. LED – Light Emitting Diodes
Electron
High Energy +
Hole
Low Energy

37. LED – Light Emitting Diodes
Electron and Hole
Combine +

38. Zener Diode
Made to operate at a voltage greater than normal breakdown voltage.
Manufacture with a specific voltage in mind.
Voltage is determined by the resistance.

39. Zener Diode Symbol

40. Temperature Coefficient
Positive – Breakdown voltage increases with Temperature.
Operate in the 4 – 5 volt range
Negative – Breakdown voltage Decreases with Temperature.
Operate at less than 4 volts.

41. Silicon Controlled Rectifier (SCR)
Anode
Cathode
Gate

42. Silicon Controlled Rectifier (SCR)
Turn on Gate
Diode Works!!!!

43. Transistor

44. Bipolar or Junction Transistor. Three layer device. Amplification
Switch

45. N-P-N Transistor
Collector N
Base P N
Emitter

46. P-N-P Transistor
Collector P
Base N P
Emitter

47. Transistor Use Type Material Major Use NPN PNP Germanium Silicon
High or Low power
Switching
High Frequency

48. Transistor Packaging

49. Transistor Packaging
Part
Number

50. Transistor
Operation

51. Collector
Base
Emitter

54. IC IB IE e- e- e- e- e- e- e- e- + + + + e- e- e- e- e- e- C B E
N-P-N Transistor IC C e- e- e- e- e- IB e- e- e- B + + + + e- e-
Diode
Turns
On!!! e- e- e- e- IE E

55. IC IB IE + + + + + + + + + + C B E P-N-P Transistor Diode Turns On!!!

56. Transistor Testing - Resistance
Forward – Low Resistance C B E
Reverse – Low High Resistance

57. Transistor Testing