This document discusses covalent bonding and the intrinsic materials used in semiconductors. It explains that to understand why silicon, germanium, and gallium arsenide are commonly used semiconductors, it is important to examine the atomic structure of each material and how the atoms are bound together in a crystalline structure. The document notes that atoms are made up of electrons, protons, and neutrons, with electrons orbiting the central nucleus formed by protons and neutrons.

1. COVALENT BONDING
AND INTRINSIC
MATERIALS

2. To fully appreciate why Si, Ge, and GaAs are the
semiconductors of choice for the elec-tronics
industry requires some understanding of the
atomic structure of each and how the atoms are
bound together to form a crystalline structure.
The fundamental components of an atom are
the electron, proton, and neutron. In the lattice
structure, neutrons and protons form the
nucleus and electrons appear in fixed orbits
around the nucleus. The Bohr model for the
three materials is provided in Fig. 1.3 .