1. DMT 121/3 : ELECTRONIC I DMT 121/3 Electronic 1 Pn. Shariffah Zarihan bt Syed Zaharim Helmi 04-9853337 / 012-4539120 zarihan@unimap.edu.my

2. DMT 121/3 : ELECTRONIC I Contents Ch 01 – Introduction to Semiconductor Ch 02 – Diode Applications Ch 03 – Bipolar Junction Transistors (BJTs) Ch 04 – DC BJT Biasing Ch 05 – Field – Effects Transistors (FETs) TEXT BOOK : Robert L. Boystead & Louis Nashelsky, ELECTRONIC DEVICES AND CIRCUIT THEORY, Ninth Edition, 2006

3. DMT 121/3 : ELECTRONIC I Lab Modules Lab 1 : Introduction to Basic Laboratory Equipment Lab 2: Introduction to Diode Lab 3: Diode as Rectifier Lab 4: Limiter and Clamper Circuits Lab 5: Current & Voltage Characteristics of BJT Lab 6: Voltage Divider Biasing

4. DMT 121/3 : ELECTRONIC I Evaluation Contribution Final Examination : 50 % Course Works: 50 % Details of course work contribution Lab works : 30 % Test : 10 % Lab Test: 10 %

5. DMT 121/3 : ELECTRONIC I Time Table Lecture – Monday (8.00 am – 10.00 am), BKS 1 Lab – Thursday (8.00 am – 10.00 am), MMS Attendance – Compulsory, attendance will be recorded.

6. DMT 121/3 : ELECTRONIC I Semiconductor Materials History of Semiconductor Devices

7. DMT 121/3 : ELECTRONIC I Semiconductor Materials Definition : Semiconductors are a special class of elements having a conductivity between that of a good conductor and that of an insulator

8. DMT 121/3 : ELECTRONIC I Semiconductor Materials Single crystal – Germanium (Ge) and Silicon (Si) Compound Semiconductor – Gallium Arsenide (GaAs), Cadmium Sulfide (CdS), Gallium Nitride (GaN) and Gallium Arsenide phosphide (GaAsP). Mostly used : Ge, Si and GaAs

9. DMT 121/3 : ELECTRONIC I Semiconductor Materials Ge – First discovered. Used as Diode in 1939, transistor in 1947. Sensitive to changes in temperature – suffer reliability problem. Si – Introduced in 1954 (as transistor), less sensitive to temperature. Abundant materials on earth. Over the time – its sensitive to issue of speed. GaAs – in 1970 (transistor), 5x speed faster than Si. Problem – difficult to manufacture, expensive, had little design support at the early stage.

10. DMT 121/3 : ELECTRONIC I Columns: Similar Valence Structure Electropositive elements: Readily give up electrons to become + ions. Electronegative elements: Readily acquire electrons to become - ions. THE PERIODIC TABLE He Ne Ar Kr Xe Rn inert gases accept 1e accept 2e give up 1e give up 2e give up 3e F Li Be Metal Nonmetal Intermediate H Na Cl Br I At O S Mg Ca Sr Ba Ra K Rb Cs Fr Sc Y Se Te Po

11. DMT 121/3 : ELECTRONIC I Electropositive elements: Readily give up electrons to become + ions. Electronegative elements: Readily acquire electrons to become - ions.

12. DMT 121/3 : ELECTRONIC I Semiconductors, Conductors, and Insulators  Conductors  material that easily conducts electrical current.  The best conductors are single-element material (e.g copper,silver,gold,aluminum,ect.)  One valence electron very loosely bound to the atom- free electron  Insulators  material does not conduct electric current  valence electron are tightly bound to the atom – less free electron  Semiconductors  material between conductors and insulators in its ability to conduct electric current  in its pure (intrinsic) state is neither a good conductor nor a good insulator  most commonly use semiconductor- silicon(Si), germanium(Ge), and carbon(C).  contains four valence electrons

13. DMT 121/3 : ELECTRONIC I Covalent Bonding & Intrinsic Materials Atom = electron + proton + neutron Nucleus = neutrons + protons Protons (positive charge) Neutrons (uncharged) Nucleus (core of atom) Electrons (negative charge) ATOM

14. DMT 121/3 : ELECTRONIC I Atomic Structure No. of electron in each shell N e = 2(n) 2 n = no of shell.

15. DMT 121/3 : ELECTRONIC I Covalent Bonding Covalent bonding of the Silicon atom Covalent bonding of the GaAs crystal

16. DMT 121/3 : ELECTRONIC I Intrinsic Carriers Table 1.1 Intrinsic Carriers SemiconductorIntrinsic Carriers (per cubic centimeter) GaAs1.7 x 10 6 Si1.5 x 10 10 Ge2.5 x 10 13 Intrinsic (pure) carriers – The free electrons in a material due to only external causes Ge has the highest number of carriers and GaAs has the lowest intrinsic carriers. The term intrinsic (pure) is applied to any semiconductor material that has carefully refined to reduce the number of impurities to a very low level – essentially as pure as can be made available through modern technology

17. DMT 121/3 : ELECTRONIC I Relative Mobility Factor µ n Table 1.2 Relative Mobility Factor Semiconductorµ n (cm 2 /V-s) Si 1500 Ge3900 GaAs8500 Relative mobility – the ability of the free carriers to move throughout the material. GaAs has 5X the mobility of free carriers compared to Si, a factor that results in response times using GaAs electronic devices is 5X those of the same device made from Si. Ge has more than twice the mobility of electrons in Si, a factor that results in the continued of Ge in high-speed radio frequency applications.

18. DMT 121/3 : ELECTRONIC I Interesting difference between Semiconductors and Conductors Conductors – Resistance increases with the increase in heat, because their vibration pattern about relatively fixed location makes it increasingly difficult for a sustained flow of carriers through the material – positive temperature coefficient. Semiconductors – Exhibit an increased level of conductivity with the application of heat. As the temperature rises, an increasing number of valence electron absorb sufficient thermal energy to break the covalent bond and contribute to the number of free carriers – negative temperature effects

19. DMT 121/3 : ELECTRONIC I Energy Levels Fig. 1.6 Energy levels: conduction and valence bands of an insulator, a semiconductor, and a conductor.

20. DMT 121/3 : ELECTRONIC I Extrinsic Materials : n-Type and P- Type Materials The characteristics of a semiconductor material can be altered significantly by the addition of a specific purity atoms to relatively pure semiconductor materials – this process is known as doping process A semiconductor that has been subjected to the doping process is called an extrinsic materials. Extrinsic Materials are n-type material [five valence electrons (pentavalent)] and p-type material [three valence electrons atom (trivalent)]

21. DMT 121/3 : ELECTRONIC I n-Type Material n-Type material is created by introducing the impurity (bendasing) elements that have five valence electrons (pentavalent). There are antimony (Sb), Arsenic (As) and phosphorous (P). Fig. 1.7 Antimony impurity in n-type material Diffused impurities with five valence electrons are called donor atoms

22. DMT 121/3 : ELECTRONIC I n-Type Material The effect of this doping cause the energy level (called the donor level) appears in the forbidden band with E g significantly less than intrinsic material. This cause less thermal energy to move free electron (due to added impurity) into conduction band at room temperature. Fig. 1.8 Effect of donor impurities on the energy band structure

23. DMT 121/3 : ELECTRONIC I n-Type Material Pentavalent atoms is an n-type semiconductor (n stands for the negative charge on electrons). The electrons are called the majority carrier in n-type materials. In n-type material there are also a few holes that are created when electrons-holes pairs are thermally generated Holes in n-type materials are called minority carrier

24. DMT 121/3 : ELECTRONIC I p-Type Material Si or Ge doped with impurities atoms having three valence electrons. Mostly used are boron (B), gallium (Ga) and indium (In). The void (vacancy) is called ‘hole’ represented by small circle or a ‘+’ sign. Fig. 1.9 Boron impurity in p-type material. Diffused impurities with three valence electrons are called acceptor atoms

25. DMT 121/3 : ELECTRONIC I Electron versus Hole Flow With sufficient kinetic energy to break its covalent bond, the electron will fills the void created by a hole, then a vacancy or hole, will be created in the covalent bond that released the electron.

26. DMT 121/3 : ELECTRONIC I p-Type Materials In p-type materials the hole is the majority carrier and the electron is the minority carrier. Holes can be thought as +ve charges because the absence of electron leaves a net +ve charge on the atom.

27. DMT 121/3 : ELECTRONIC I Semiconductor Diode Diode Simple construction of electronic device, it a joining between n-type and p-type material (joining one with majority carrier of electron to one with a majority carrier of holes)

28. DMT 121/3 : ELECTRONIC I Diode @ No Applied Bias (V D =0)

29. DMT 121/3 : ELECTRONIC I Reverse Bias (V D < 0 V) Fig. 1.13 Reverse-biased p–n junction. (a) Internal distribution of charge under reverse-bias conditions; (b) reverse-bias polarity and direction of reverse saturation current.

30. DMT 121/3 : ELECTRONIC I Forward Bias (V D > 0 V) (b) Fig. 1.14 Forward-biased p–n junction. (a) Internal distribution of charge under forward-bias conditions; (b) forward-bias polarity and direction of resulting current.

31. DMT 121/3 : ELECTRONIC I Diode Characteristics Curve Fig. 1.15 Silicon semiconductor diode characteristics.

32. DMT 121/3 : ELECTRONIC I Ge, Si and GaAs Fig. 1.18 Comparison of Ge, Si, and GaAs diodes.

33. DMT 121/3 : ELECTRONIC I Temperature Effects Fig. 1.19 Variation in Si diode characteristics with temperature change.

34. DMT 121/3 : ELECTRONIC I Ideal Vs Practical Fig. 1.21 Ideal semiconductor diode: (a) forward-biased; (b) reverse-biased. (Short circuit equivalent –fwd bias, actual case R ≠ 0) (Open circuit equivalent – Reverse bias, actual case saturation current Is ≠ 0) Fig. 1.22 Ideal versus actual semiconductor characteristics.

35. DMT 121/3 : ELECTRONIC I Ideal Vs Practical Semiconductor diode behaves in a manner similar to mechanical switch that can control the current flow between it’s two terminal However, semiconductor diode different from a mechanical switch in the sense that it permit the current flow in one direction

36. DMT 121/3 : ELECTRONIC I Approximate Diode

37. DMT 121/3 : ELECTRONIC I Resistance Levels DC or Static Response Application of dc voltage will result in an operating point on the characteristic curve will not change with time. Fig. 1.23 Determining the dc resistance of a diode at a particular operating point. In general, the higher the current through a diode, the lower is the dc resistance level.

38. DMT 121/3 : ELECTRONIC I Resistance Levels AC or Dynamic Response Fig. 1.25 Defining the dynamic or ac resistance.

39. DMT 121/3 : ELECTRONIC I Resistance Levels Average AC Response Fig. 1.28 Determining the average ac resistance between indicated limits.

40. DMT 121/3 : ELECTRONIC I Diode Equivalent Model

41. DMT 121/3 : ELECTRONIC I Example 10V 1.0kΩ Determine the forward voltage (V F ) and forward current [I F ]. Also find the voltage across the limiting resistor. Assumed rd’ = 10  at the determined value of forward.

42. DMT 121/3 : ELECTRONIC I Example Determine the Reverse voltage (V R ). Also find the voltage across the limiting resistor. Assumed I R = 1 µA. Answer: V RLIMIT =1mV V R =4.999V

43. DMT 121/3 : ELECTRONIC I Diode Testing Analog MM (or Ohm meter testing) Fig. 1.42 Checking a diode with an ohmmeter.

44. DMT 121/3 : ELECTRONIC I FIGURE 1-38 DMM diode test on a properly functioning diode. Digital MM Diode Testing

45. DMT 121/3 : ELECTRONIC I FIGURE 1-39 Testing a defective diode. Digital MM (Testing Defective Diode) Diode Testing

46. DMT 121/3 : ELECTRONIC I Fig. 1.38 Semiconductor diode notation. Robert L. Boylestad Electronic Devices and Circuit Theory, 9e Copyright ©2006 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Diode Notation

47. DMT 121/3 : ELECTRONIC I Zener Diode Fig. Characteristics of Zener region. Fig. 1.46 Conduction direction: (a) Zener diode; (b) semiconductor diode; (c) resistive element.

48. DMT 121/3 : ELECTRONIC I The Zener region is in the diode’s reverse-bias region. At some point the reverse bias voltage is so large the diode breaks down and the reverse current increases dramatically. Zener Region avalanche (runtuhan) breakdown voltageThis maximum voltage is called avalanche (runtuhan) breakdown voltage avalanche currentThe current is called avalanche current. 48

49. DMT 121/3 : ELECTRONIC I …..eNd….. …ChapTeR 1…