SQA Higher Physics Practice Exam

In n-type semiconductors, the primary characteristic is their enhancement of electrical conductivity due to the presence of additional electrons. This is achieved by doping the semiconductor material, typically silicon, with donor atoms that have more valence electrons than the semiconductor itself. Common donor atoms include phosphorus or arsenic, which each have five valence electrons, compared to the four valence electrons of silicon.

When these donor atoms are added, they contribute extra electrons to the semiconductor's conduction band, significantly increasing the number of charge carriers available for conduction. This creates an abundance of negatively charged carriers (electrons) in the material, making it easier for electricity to flow through the semiconductor. Hence, the statement regarding doping with donor atoms being responsible for the properties of n-type semiconductors correctly identifies the mechanism that enhances conductivity in these materials.