Semiconductors and p–n Junctions
Use energy bands, charge carriers and junction behaviour to explain diodes, LEDs and solar cells.
How to study Higher Physics
Move between physical models, relationships, units, graphs and justified conclusions, while using current official materials for exact paper and assignment conditions.
Core concepts
Concept 1
conductors, insulators and semiconductor bands
Exam cue: Distinguish majority carriers in n-type and p-type material.
Concept 2
intrinsic and doped semiconductors
Exam cue: Describe bias in terms of the junction barrier and carrier flow.
Concept 3
p–n junction bias
Exam cue: Relate emitted photon energy to the semiconductor energy gap.
Concept 4
LED and photovoltaic energy conversion
Risk pitfalls and guardrails
Saying n-type material is negatively charged overall.
Guardrail: Check assumptions, prefixes, units, significant figures and whether the statement is supported by evidence.
Treating holes as physical positive particles entering from outside.
Guardrail: Check assumptions, prefixes, units, significant figures and whether the statement is supported by evidence.
Assuming a diode conducts equally in both directions.
Guardrail: Choose a positive direction and preserve signs through the calculation before interpreting the result.
Memory anchors
n-type majority carrier
Electrons, while the material remains electrically neutral overall.
p-type majority carrier
Holes, while the material remains electrically neutral overall.
Forward bias
Reduces the junction barrier and allows substantial current.
Reverse bias
Increases the effective barrier and gives very small current.
LED
Electron–hole recombination releases energy as photons.
Photovoltaic cell
Absorbed photons create charge carriers that the junction separates to produce electrical energy.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
What is the valence band in a solid?
What is the conduction band?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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