Effect of doping on intrinsic semiconductors Which electrical characteristic of an intrinsic semiconductor is primarily controlled by adding impurities (doping)?

Introduction / Context:Doping transforms intrinsic semiconductors into n-type or p-type materials by dramatically changing carrier concentrations. This directly alters how easily charge flows through the crystal, which is captured by the material’s conductivity (or, inversely, its resistivity/resistance).

Given Data / Assumptions:

• Intrinsic semiconductor baseline (very low carrier density).
• Donor (n-type) or acceptor (p-type) dopants introduced in parts-per-million or lower.
• Macroscopic device dimensions where bulk properties dominate.

Concept / Approach:Conductivity sigma equals q * (n * mu_n + p * mu_p), where q is electron charge, n and p are electron and hole densities, and mu are mobilities. Doping changes n or p by orders of magnitude, so the dominant controlled parameter is conductivity. Resistance depends on geometry as well, and power is not a material property but a circuit operating quantity (P = V * I).

Step-by-Step Solution:Introduce dopants: donors increase n, acceptors increase p.Carrier density change: many orders of magnitude relative to intrinsic.Conductivity rises correspondingly; resistivity falls.Therefore, the primary controlled characteristic is conductivity.

Verification / Alternative check:Sheet resistance measurements of doped wafers show strong dependence on dopant dose and activation, confirming conductivity control via doping.

Why Other Options Are Wrong:Resistance: related but secondary; geometry matters, whereas conductivity is the intrinsic material parameter.Power: depends on operating voltage/current, not a material property.All of the above: includes power, which is incorrect.

Common Pitfalls:Confusing conductivity (material property) with conductance or resistance (device-level parameters influenced by dimensions).

Final Answer:conductivity