High-yield facts (memorize first):

• Si: E_g = 1.1 eV, barrier = 0.7 V | Ge: E_g = 0.67 eV, barrier = 0.3 V
• n-type → pentavalent (P, As, Sb) | p-type → trivalent (B, Al, Ga, In)
• Both n-type and p-type are electrically NEUTRAL
• Zener = reverse bias | Photodiode = reverse bias | LED = forward bias | Solar = no bias
• Full-wave rectifier: f_out = 2f_in; half-wave: f_out = f_in
• NAND and NOR are BOTH universal gates
• De Morgan: break bar, flip operator (+↔·)

Quick identification shortcuts:

• Truth table with "0 only at (1,1)" → NAND gate
• Truth table with "1 only at (0,0)" → NOR gate
• Truth table with "1 only at (1,1)" → AND gate
• Truth table with "0 only at (0,0)" → OR gate

Numerical strategy (mass action law):

1. Identify n_i and the majority carrier concentration
2. Apply n_minority = n_$i^{2}$ / n_majority
3. Check units (all $m^{-3}$ or all c$m^{-3}$)
4. Confirm: doped majority >> n_i >> doped minority

LED color strategy:

• Use λ(μm) = 1.24 / E_g(eV) shortcut
• Large E_g → small λ → blue/UV | Small E_g → large λ → red/IR

Time allocation in exam: This chapter's 2–3 NEET questions are among the fastest to answer with memorization. Logic gate truth tables take 20–30 seconds each. Semiconductor type from dopant takes 10 seconds. Reserve numerical calculation for mass-action-law questions (~90 seconds). Total expected time: 4–6 minutes for full chapter allocation.

NEET 2026 prediction: High probability questions include (a) gate identification from truth table, (b) special diode application/bias MCQ, (c) mass action law numerical. Medium probability: De Morgan simplification, rectifier frequency. Lower probability: band gap classification, temperature coefficient.