Final answer:
The doping of GaAs with silicon could lead to p-type or n-type conductivity, based on whether silicon occupies the site of gallium or arsenic, respectively. However, with equal probability of occupying either site, the result of Si doping can be a balance of p-type and n-type characteristics, possibly leading to intrinsic-like behavior.So, the correct answer is (c) N-type conductivity.
Step-by-step explanation:
The doping of GaAs (gallium arsenide) with silicon can lead to either p-type or n-type conductivity depending on which site the silicon atom occupies.
If silicon substitutes for gallium (Ga), which has three valence electrons, it will act as an acceptor because silicon has four valence electrons.
This would lead to the formation of p-type material due to the creation of holes (positive charge carriers).
Conversely, if silicon substitutes for arsenic (As), which has five valence electrons, it will act as a donor and contribute an extra electron, leading to an n-type semiconductor due to the additional negative charge carriers.
However, the question states that silicon is equally likely to occupy either position.
Since both possibilities are equally likely, silicon doping will not necessarily lead to a specific (p-type or n-type) conductivity type.
Instead, it can lead to compensation, where the effect of donors (Si at As site) and acceptors (Si at Ga site) balance each other, potentially leading to intrinsic-like behaviour or other complex conductivity types, depending on the exact conditions and ratios of occupancy.
So, the correct answer is (c) N-type conductivity.