ABSTRACT

Thermal effects in solids are a manifestation of the vibrational motion of the molecules or atoms that make up the material. This chapter introduces the basic concepts of phonon transport along with the derivation, from them, of the thermodynamical properties relevant to the electrical and optical features of a crystal lattice. In turn, thermal effects influence the electrical and optical properties of semiconductors. In particular, in micro- and nanoelectronics, the formation of hot spots and the high thermal power generation per unit area are major issues for an efficient design of semiconductor devices. The most basic manifestation of the crystal temperature is the vibration of the atoms around their equilibrium positions represented by the points of the ideal Bravais lattice. Crystal heating due to an electron flow is considered rather important in graphene. It can influence the properties related to the electrical characteristics but can also create hot spots with rather high temperatures and the possibility of damaging the material.