Define intrinsic and extrinsic semiconductors. Explain the concept of biasing a diode.

Here are the solutions for the questions from Section III, Option 3 and Option 4:

OPTION 3: ELECTRONICS

1. (a) (i)

• Intrinsic semiconductors are pure semiconductor materials (e.g., pure silicon or germanium) with no impurities added. Their electrical conductivity is solely due to thermally generated electron-hole pairs.
• Extrinsic semiconductors are doped semiconductor materials, meaning impurities (dopants) have been added to enhance their conductivity. They can be n-type (doped with donor impurities, having excess electrons) or p-type (doped with acceptor impurities, having excess holes).

1. (a) (ii)

• Biasing a diode