Pure Si at 500 K has electron and hole concentrations of 1.5 × 10¹⁶ m⁻³ each. After doping with indium, hole concentration becomes 4.5 × 10²² m⁻³. Find minority electron concentration and type of semiconductor.
Options

Question

Pure Si at 500 K has electron and hole concentrations of 1.5 × 10¹⁶ m⁻³ each. After doping with indium, hole concentration becomes 4.5 × 10²² m⁻³. Find minority electron concentration and type of semiconductor.

Options

G1 Physics · Accepted Answer

Indium is a trivalent acceptor, so the material is p-type, with holes as majority carriers. Apply mass-action law nₑnₕ = nᵢ². Thus nₑ = (1.5 × 10¹⁶)²/(4.5 × 10²²) = 2.25 × 10³²/4.5 × 10²² = 5 × 10⁹ m⁻³. Numerical result matches Option D; however the scanned option calls it n-type, inconsistent with indium doping. Correct type is p-type. Source option must be checked. Final answer: Option D.