Advanced Placement (AP) Chemistry Practice Exam

What type of doping involves adding a substance with one less valence electron?

1. n-doping

2. p-doping

3. compensatory doping

4. substitutional doping

The correct answer is: p-doping

The process of p-doping involves adding a substance that has one less valence electron compared to the semiconductor material. In semiconductors like silicon, which has four valence electrons, introducing an element such as boron, which has only three valence electrons, creates "holes" or vacancies where an electron can be absent. These holes can accept electrons, allowing the material to conduct electricity. This mechanism effectively increases the number of positive charge carriers in the semiconductor, enhancing its conductivity. Therefore, p-doping is specifically characterized by the introduction of elements that create these electron deficiencies, distinguishing it from n-doping, which involves adding elements with extra valence electrons to increase the number of negative charge carriers.