Semiconductor Physics Model Answers PDF - ELE 222, Spring 2024 - 2025

‫المعهد الكندي العالي لتكنولوجيا‬ ‫الهندسة و اإلدارة‬ Engineering Department Course Name: Electronic Devices Communication Engineering...

‫المعهد الكندي العالي لتكنولوجيا‬ ‫الهندسة و اإلدارة‬ Engineering Department Course Name: Electronic Devices Communication Engineering Course Code: ELE 222 Spring Semester 2024 - 2025 Sheet’s Quiz Date: ---------------------------------------------- Sheet 1 | Semiconductor Physics Model Answer No. of Pages: 3 page(s) Instructor Name: Dr. Ashraf TA: Eng. Nemine Answer the following questions: Model Answer Q1. A semiconductor is formed by ……… bonds. 1. Covalent 3. Co-ordinate 2. Electrovalent 4. None of the above Q2. A semiconductor has ………… temperature coefficient of resistance. 1. Positive 3. Negative 2. Zero 4. None of the above Q3. The most commonly used semiconductor is ……….. 1. Germanium 3. Carbon 2. Silicon 4. Sulphur Q4. A semiconductor has generally ……………… valence electrons. 1. 2 3. 6 2. 3 4. 4 Q5. The resistivity of pure germanium under standard conditions is about ………. 1. 6 x 104 Ω cm 3. 3 x 106 Ω cm 2. 60 Ω cm 4. 6 x 10-4Ω cm Q6. The resistivity of a pure silicon is about …………… 1. 100 Ω cm 3. 3 x 105 Ω m 2. 6000 Ω cm 4. 6 x 10-8 Ω cm Q7. When a pure semiconductor is heated, its resistance ………….. 1. Goes up 3. Remains the same 2. Goes down 4. Can’t say Q8. The strength of a semiconductor crystal comes from …….. 1. Forces between nuclei 3. Electron-pair bonds 2. Forces between protons 4. None of the above ‫ا ل م ع ه د ا ل ك ن د ي ا ل ع ا ل ي ل ت ك ن و ل و ج ي ا ا ل ه ن د س ة و ا إل د ا ر ة‬ Page 1  ‫المعهد الكندي العالي لتكنولوجيا‬ ‫الهندسة و اإلدارة‬ Q9. When a pentavalent impurity is added to a pure semiconductor, it becomes ……… 1. An insulator 3. p-type semiconductor 2. An intrinsic semiconductor 4. n-type semiconductor Q10. Addition of pentavalent impurity to a semiconductor creates many …….. 1. Free electrons 3. Valence electrons 2. Holes 4. Bound electrons Q11. A pentavalent impurity has ………. Valence electrons 1. 3 3. 4 2. 5 4. 6 Q12. A trivalent impurity has ….. Valence electrons 1. 4 3. 6 2. 5 4. 3 Q13. Addition of trivalent impurity to a semiconductor creates many …….. 1. Holes 3. Valence electrons 2. Free electrons 4. Bound electrons Q14. A hole in a semiconductor is defined as ……………. 1. A free electron 3. A free proton 2. The incomplete part of an electron 4. A free neutron pair bond Q15. As the doping to a pure semiconductor increases, the bulk resistance of the semiconductor ……….. 1. Remains the same 3. Decreases 2. Increases 4. None of the above Q16. A hole and electron in close proximity would tend to ………. 1. Repel each other 3. Have no effect on each other 2. Attract each other 4. None of the above Q17. In a semiconductor, current conduction is due to …….. 1. Only holes 3. Holes and free electrons 2. Only free electrons 4. None of the above Q18 At room temperature, an intrinsic semiconductor has ………. 1. Many holes only 4. No holes or free electron 2. A few free electrons and holes 3. Many free electrons only ‫ا ل م ع ه د ا ل ك ن د ي ا ل ع ا ل ي ل ت ك ن و ل و ج ي ا ا ل ه ن د س ة و ا إل د ا ر ة‬ Page 2  ‫المعهد الكندي العالي لتكنولوجيا‬ ‫الهندسة و اإلدارة‬ Q19. A forward biased approximated pn junction diode has a resistance of the order of…………….. 1. Ω 3. MΩ 2. kΩ 4. None of the above Q20. The battery connections required to forward bias a pn junction are …… 1. +ve terminal to p and –ve terminal to n 2. -ve terminal to p and +ve terminal to n 3. -ve terminal to p and –ve terminal 4. None of the above to n Q21. The barrier voltage at a pn junction for germanium is about ……… 1. 0.5 V 3. Zero 2. 0.7 V 4. 0.3 V Q22. In the depletion region of a pn junction, there is a shortage of …….. 1. Acceptor ions 3. Donor ions 2. Holes and electrons 4. None of the above Q23. A reverse bias pn junction has ………… 1. Very narrow depletion layer 3. Very low resistance 2. Almost no current 4. Large current flow Q24. With forward bias to a pn junction , the width of depletion layer ……… 1. Decreases 2. Increases 3. Remains the same 4. None of the above Q25. Under normal conditions a diode conducts current when it is …………… 1. reverse biased 2. forward biased 3. avalanched 4. saturated ‫ا ل م ع ه د ا ل ك ن د ي ا ل ع ا ل ي ل ت ك ن و ل و ج ي ا ا ل ه ن د س ة و ا إل د ا ر ة‬ Page 3