Semiconductor Electronics — Class 12 CBSE Physics revision notes
A 7-page visual revision sheet for Semiconductor Electronics, written for Class 12 CBSE Physics. Formulas, diagrams and the traps that cost marks, laid out to be read the night before rather than the term before. Free, and it opens inside CapCompass.
Page 1 as PDF
Semiconductor Electronics in one look
a material poised between conductor and insulator, and a junction that only lets current through one way
Conductor vs insulator vs semiconductor
- conduction and valence bands overlap
- plenty of free electrons, always
- conductivity falls as temperature rises
- a wide gap, several eV, between the bands
- electrons almost never cross it
- conductivity negligible at ordinary temperatures
- a narrow gap, about 1 eV, between the bands
- heat alone lifts a few electrons across
- conductivity rises as temperature rises
Two carriers, not one
- heat breaks a bond: one electron freed, one hole made
- a hole acts as a positive charge carrier
- in a pure (intrinsic) crystal n_e=n_h=n_i
- electrons drift toward +, holes toward −
- a hole moves when a neighbour's electron hops in
- both carriers add to the current
Page 1 of 7. The full sheet, all 7 pages, opens free in the app.
What this Semiconductor Electronics sheet covers
- Conductor vs insulator vs semiconductor
- Conductor
- Insulator
- Semiconductor
- Two carriers, not one
- Heat makes pairs
- A field moves them
- Carriers and conductivity
- current from both carriers
- mass-action law, doped or intrinsic
- n-type vs p-type doping
- n-type
- p-type
- Majority carriers and doping level
- n-type, donor concentration N_D
- p-type, acceptor concentration N_A
- The p-n junction
- Diffusion and drift
- The barrier
- Forward bias vs reverse bias
- Forward bias
- Reverse bias
- Reverse leakage and the I-V curve
- reverse saturation current, minority carriers only
- Rectifiers
- half-wave, average output
- full-wave (centre-tap or bridge), average output
- Zener diode: holding a voltage
- Its curve
- As a regulator
- Diodes and light
- Logic gates
- Boolean expressions
- NOT, AND, OR
- NAND, NOR
- The six gates
- Universal gates and gate circuits
- Diode logic and the transistor's curves
- Traps that cost marks
- Tricks that save time
How CapCompass uses this sheet
These notes are not a standalone PDF. CapCompass plans Physics chapter by chapter against your real exam dates and free hours, and when the plan reaches Semiconductor Electronics the sheet opens inside the study block itself — at the page covering the sub-topic that block is on, with the timer still running. Revision arrives at the moment the plan says revise, instead of having to be gone looking for.