We will see in Chapter 12 that semiconductors are materials that conduct electricity better than nonmetals but not as well as metals. The only two elements in the periodic table that are technologically useful semiconductors are silicon and germanium. Integrated circuits in computer chips today are based on silicon. Compound semiconductors are also used in the electronics industry. Examples are gallium arsenide, GaAs; gallium phosphide, GaP; cadmium sulfide, CdS; cadium selenide, CdSe.
(a) What is the relationship between the compound semiconductors' compositions and the positions of their elements on the periodic table relative to Si and Ge?
(b) Workers in the semiconductor industry refer to "II-VI" and "III-V" materials, using Roman numerals; can you identify which compound semiconductors are II-VI and which are III-V?
(c) Suggest other compositions of compound semiconductors based on the positions of their elements in the periodic table.