The Claim to Verify

"An n-type semiconductor has electrons as majority carriers, yet it is electrically neutral."

Step-by-Step Reasoning

Step 1: Start with pure silicon

• Silicon atom: 14 protons (+14), 14 electrons (−14) → net charge = 0
• Silicon crystal: enormous number of Si atoms, each electrically neutral → bulk is neutral ✓

Step 2: Add a phosphorus dopant atom (pentavalent)

• Phosphorus atom: 15 protons (+15), 15 electrons (−15) → net charge = 0 per P atom
• The P atom replaces one Si atom in the lattice
• Net charge contributed by P atom to the crystal = 0 (15 protons and 15 electrons come in together)

Step 3: What happens to the extra electron?

• P has 5 valence electrons; Si lattice needs only 4 to complete covalent bonds
• The 5th electron of P is loosely bound → becomes a free conduction electron
• BUT: This electron came WITH the phosphorus atom, which also brought its +15 nucleus
• The P nucleus has +15 protons while $P^{+}$ (after donating electron) has +15 −14 = net +1 ionic charge
• The donated electron (charge −1) exactly cancels the $P^{+}$ ion charge (+1)

Step 4: Count the charges in n-type silicon

• Original Si atoms: charge = 0 each
• P dopant atoms: contribute +1 ($P^{+}$ ion) + (−1) (free electron) = 0 net charge
• Total crystal charge = 0 → ELECTRICALLY NEUTRAL ✓

Step 5: Why the confusion arises

• Students focus only on the free electrons (negative) without accounting for the corresponding positive donor ions ($P^{+}$) that remain fixed in the lattice
• The free electrons move (they're mobile), but the $P^{+}$ ions stay fixed in the crystal lattice
• The material has "extra" mobile electrons, but these were already "paid for" by the +1 ionic charge of each $P^{+}$ dopant ion

Conclusion

"n-type" describes the TYPE of MAJORITY CARRIER, not the SIGN of NET CHARGE. The crystal always maintains electrical neutrality because every doping event introduces equal and opposite charges simultaneously.

NEET answer: When asked "Is n-type semiconductor electrically charged?", the answer is: No, it is electrically neutral. The correct option in NEET MCQs will always be "electrically neutral" regardless of how the trap is worded.