Energy Bands, Doping and the p-n Junction

Name: Energy Bands, Doping and the p-n Junction
Author: StemPy Lab

Why copper conducts, glass does not and silicon can be switched. Energy bands and the band gap, intrinsic and doped (n-type and p-type) crystals, and the p-n junction with its depletion layer, its barrier and its current-voltage curve. It serves the Indian syllabus (NCERT, NEET, JEE Main) and the matching topic of A-Level and IB.

3 lessons, about 1 h 40 min3 simulations11 problems6 practice questionsPython in every lesson

Created by StemPy Lab

Course outline (3 lessons)

Lesson 1about 35 min
Energy bands in solids
In a crystal, the energy levels of the outer electrons spread into bands. The valence band is the highest band filled with electrons. The conduction band lies above it. The gap between them decides whether the solid is a conductor, an insulator or a semiconductor. Silicon has a gap of 1.12 eV, germanium of 0.67 eV.
1 simulation2 practice questions1 Python program4 problems1 Python lab
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Lesson 2about 30 min
Intrinsic and extrinsic semiconductors
A pure semiconductor has as many holes as electrons. Adding a few atoms of a different group changes it. A donor atom (group 15) gives an extra electron and makes n-type material. An acceptor atom (group 13) makes a hole and gives p-type material. In either type, the product of the two carrier numbers stays $n_i^2$ .
1 simulation2 practice questions1 Python program4 problems
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Lesson 3about 35 min
The p-n junction and the diode
Where a p-type crystal meets an n-type crystal, diffusion leaves a layer without free carriers: the depletion layer, with a barrier of about 0.7 V for silicon. A forward bias lowers the barrier, and the current grows very fast. A reverse bias raises it, and only a tiny leakage current flows. So the junction is a diode: it passes current one way.
1 simulation2 practice questions1 Python program3 problems1 Python lab1 question set1 note
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Energy Bands and Junctions: Practice Paper

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Energy Bands, Doping and the p-n Junction

Course outline (3 lessons)

Energy bands in solids

Intrinsic and extrinsic semiconductors

The p-n junction and the diode

Test Your Learning

Your teacher

Discussion (0)