Question

How can an n-type semiconductor be produced from pure germanium? How can a p-type semiconductor be produced from pure germanium? Explain how n-type and p‑type semiconductors increase electrical conductivity over that of pure germanium.

Short answer

Doping with group 5A will produce an n-type semiconductor.

Doping with group 3A will produce a p-type semiconductor.

Due to the addition of electrons do not need more energy to jump into the conduction band.

Step-by-step solution

Given Information

Pure Ge can be changed to an n-type and/or p-type semiconductor.

Producing n-type semiconductor from pure germanium

To produce an n-type semiconductor, dope Ge with an element with more than four valence electrons, for example, Group 5A elements. Phosphorus and arsenic are two elements that will produce an n-type semiconductor when they are doped into germanium.

Production of p-type semiconductor from pure germanium

To produce a p-type semiconductor, dope Ge with an element with less than four valence electrons, for example, Group 3A elements. Gallium or indium are two elements that will produce p-type semiconductors when they are doped into germanium.

Reason for increasing electrical conductivity

Doping germanium with 5A elements adds electrons at energies near the conduction band of germanium. Electrons do not need as many energies near the conduction band of germanium. So conduction increases.

Doping germanium with 3A elements produces a p-type semiconductor because it has fewer valence electrons than germanium, and holes at previously filled molecular orbitals are created, which induces greater electron movement.