Majority Carriers in Semiconductors In which type of semiconductor are holes the majority charge carriers under thermal equilibrium?

Introduction / Context:
Semiconductors conduct electricity through two kinds of mobile carriers: electrons in the conduction band and holes in the valence band. The relative dominance (majority vs minority) depends on doping, which introduces donors or acceptors. Recognizing which carriers dominate in various semiconductor types is foundational for device physics and circuit design.

Given Data / Assumptions:

• Thermal equilibrium (no external injection).
• Standard definitions of intrinsic, n-type, and p-type materials.
• Non-degenerate doping levels typical of electronics.

Concept / Approach:

In an intrinsic semiconductor, the electron and hole concentrations are equal (n = p = ni). In an extrinsic semiconductor, doping sets the majority species: donors (n-type) produce electrons as majority carriers, while acceptors (p-type) create holes as majority carriers. The minority concentration follows the mass-action law n * p = ni^2.

Step-by-Step Solution:

Verification / Alternative check:

Diode behavior (p–n junction) and Hall-effect measurements confirm carrier types: p-type shows positive Hall coefficient due to hole dominance.

Why Other Options Are Wrong:

• Intrinsic: n = p, no majority species.
• Extrinsic (unspecified): could be either n-type or p-type.
• n-type: electrons, not holes, are majority carriers.

Common Pitfalls:

Assuming “extrinsic” implies a specific carrier type; it simply means doped (either donors or acceptors).

Final Answer:

p-type semiconductor