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Introduction (in Hindi)
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Introduction of semiconductors and its classification. Difference with respect to metals and insulators in terms of energy bands and defining intrinsic semiconductors.

Udit Gupta is teaching live on Unacademy Plus

Udit Gupta
A Mechanical Engineer from NIT Allahabad here to help learners with physics. Also a Star ⭐ educator.

Unacademy user
Thank U sir.A very imp lesson...not many courses like this are on Unacademy.
I think Udit sir knows the value of time. Almost all his videos have more content covered in less time
Udit Gupta
3 months ago
Thanks a lot!!
plz sir rply kya ye 10 slids sufficient h jee k liye?
Udit Gupta
4 months ago
I think it covers 90% theory and 10% questions. You should try more questions for better clarity.
Sir yeh conduction band kya hota h ?
Sir yeh conduction band hota kya h?
Udit Gupta
6 months ago
You can assume it to be a state of electron when it is ready to conduct electricity... Relate it to hydrogen spectrum to understand the importance of energy of an electron in the outermost shell
really helpful thanks sir people like u are blessing for us
Udit Gupta
8 months ago
you are welcome!!

  2. WELCOME TO THE 1ST LESSONN SEMICONDUCTORS In this lesson we understand the basic principles as to why this was introduced, its advantages and a bit of terminology DON'T FORGET TO CHECK THE SPECIAL CLASSES!!

  3. INTRODUCTION 0Before 1930, flow of charge carriers was done via CRT which required high power, had low reliability and a limited life. Came in solid state semiconductors in which flow of charge carriers is within the solid itself. They required less power (light, heat or small voltage), more reliable and more life. MIMIIAIMIIAMWANNTOIMAIIAIAIRAIIAAIAIMANAT

  4. CLASSIFICATION OF METALS, SEMICONDUCTORS&INSULATORS a) Metals - Less resistivity, high conductivity On the basis of conductivity: Semiconductors Intermediate between metals and insulators Insulators - High resistivity, low conductivity Semi-c Compound Semi-C Elemental Semi-c (Si,Ge) Organic Polymer Inorganic Organic (CdS,GaAs,InP)

  5. CLASSIFICATION OF METALS, SEMICONDUCTORS & INSULATORS (b) On the basis of eneray bands: For an isolated atom Energy is decided by orbit (Bohr's model) For a crystal is solids it is not the case. For a crystal: Each electron has different energy level > These different energy levels with continuous energy variation form ENERGY BANDS Valence Band: Energy bond which includes energy levels od valence electrons Conduction Band : Energy band above valence band boud For a Si atom: Si 3s23p2 For N atoms of Si diagram has been shown

  6. CLASSIFICATION OF METALS, SEMICONDUCTORS& INSULATORS If Eg 0: Conductor, even if we have partially filled conduction band & partially empty valence band. If 0 < E, < 3eV :Semiconductor If Eg > 3eV :Insulator INIPHAIAIIAMINAIIWANIAIWNATIIAUIInRWINIMMnN

  7. CONDUCTION PROCESS IN SEMI-C (a) Intrinsic Semi-c: Most common case of Ge &Si having diamond like structure Covalent bonding or Valence Bond: 4 electrons of each are constantly shuttling back and forth Above situation prevalent @ low temperature. -) With T , electrons break away contributing to conduction thus creates a vacancy with effective positive electronic charge called a hole INIPHAIAIIAMINAIIWANIAIWNATIIAUIInRWINIMMnN

  8. CONDUCTION PROCESS IN SEMI-C For intrinsic semi-c: ne-nh-ni ni Intrinsic carrier concentration Current due to movement of electrons as well as movement of holes. -38 en INIPHAIAIIAMINAIIWANIAIWNATIIAUIInRWINIMMnN


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