Fundamentals of Silicon Carbide Technology

Chapter 2Physical Properties of Silicon Carbide

Silicon carbide (SiC) crystallizes in a wide variety of structures, each of which exhibits unique electrical, optical, thermal, and mechanical properties. The physical properties of SiC are very important subjects of academic study as well as critical parameters for accurate simulation of devices. This chapter briefly reviews the physical properties of SiC.

2.1 Crystal Structure

SiC is a compound semiconductor, which means that only a rigid stoichiometry, 50% silicon (Si) and 50% carbon (C), is allowed. The electronic structures of neutral Si and C atoms in their ground states are:

2.1

2.2

Both Si and C atoms are tetravalent elements and have four valence electrons in their outermost shells. Si and C atoms are tetrahedrally bonded with covalent bonds by sharing electron pairs in orbitals to form a SiC crystal. Each Si atom has exactly four C atom neighbors, and vice versa. The Si–C bond energy is very high (4.6 eV), which gives SiC a variety of outstanding properties, as described below.

From a crystallographic point of view, SiC is the best known example of polytypism [1–5]. Polytypism is the phenomenon where a material can adopt ...