The P-type and N-type semiconductors of a peltier are made from Bismuth (Bi) and
Tellurium (Te), respectively. The intensities of free electrons of Bi and Te are different
at the same temperature even though both substances belong to the alloy group. As
illustrated in Figure 3, the P-type and N-type semiconductors are “sandwiched”
between two ceramic substrates and the semiconductors are of cube shape. The
arrangements of the P-type and N-type cubes are such that no P-type cube is adjacent to
an N-type cube and vice versa. The P-type cubes are electron-deficit whereas the
electrons of N-type cubes are in excess.