5.1 Introduction 5

5.2 What are semiconductors? 5

5.3 The conduction mechanism in pure semiconductors 5

5.3.1 Crystal structure of semiconductors 6

5.3.2 Free-moving electrons 7

5.3.3 Movement of holes 7

5.3.4 Difference between semiconductors and conductors 9

5.3.5 Summary 9

5.4 Doping of semiconductors 9

5.4.1 N-doped crystals 9

5.4.2 P-doped crystals 11

5.4.3 The p-n junction 12

5.5 The p-n junction under radiation or the photoelectric effect 13

5.6Summary 15

6.1 Electron Flipper 16

6.1.1 How much energy in sunlight? 16

6.1.2 Case 1 - Radiation with too little energy 17

6.1.3 Case 2 - Radiation with ideal energy 18

6.1.4 Case 3 - Radiation with too high energy 18

6.2 Further losses 19

6.2.1 Effect of cell temperature 19