Semiconductor materials and their properties

Semiconductor materials are the basic materials which are used in photovoltaic (PV) devices. This chapter introduces solid-state physics and semiconductor properties that are relevant to photovoltaics without spending too much time on unnecessary information. Usually atoms in the group of semiconductor materials form crystalline structures in solid-state conditions. Ideally these structures consist of an infinite repetition of identical groups of atoms. The bonds between atoms in a semiconductor crystal are single covalent bonds. Covalent bonding is the sharing of valence electrons which are the electrons in the outer electron shell of the atom. When individual atoms are brought together in a crystalline lattice, energy bands are formed in a semiconductor material. The energy band representation of materials can visually explain the difference between insulators, semiconductors and conductors. A semiconductor's bandgap energy is low enough to achieve conductivity under specific circumstances.