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; and cadmium selenide, CdSe. (a) What is the relationship between the compound semiconductors' compositions and the positions of their elements on the periodic table relative to \(\mathrm{Si}\) and Ge? \((\mathbf{b})\) 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.

Step by step solution

01

Relationship between compound semiconductors and periodic table positions

To find the relationship between the given compounds' compositions and the positions of their elements on the periodic table, let's examine the positions of Si, Ge, Ga (gallium), As (arsenic), P (phosphorus), Cd (cadmium), S (sulfur), and Se (selenium). Si and Ge are in group IV, Ga and Al (aluminium) are in group III, As and P are in group V, while Cd is in group II, and S and Se are in group VI. Compound semiconductors mentioned in the exercise are GaAs, GaP, CdS, and CdSe. If we compare their elemental positions with Si and Ge, we can see that they are formed by combining elements from groups III-V (GaAs and GaP) and groups II-VI (CdS and CdSe). #a)# The relationship between the compound semiconductors' compositions and the positions of their elements on the periodic table relative to Si and Ge is that they are formed by combining elements from neighboring groups, such as III-V or II-VI.

02

Identification of II-VI and III-V compound semiconductors

Based on the relationship we found in Step 1, we can now identify the compound semiconductors as either II-VI or III-V: - Gallium arsenide (GaAs) and gallium phosphide (GaP) are III-V semiconductors because Ga is present in group III and As, P are present in group V. - Cadmium sulfide (CdS) and cadmium selenide (CdSe) are II-VI semiconductors because Cd is present in group II, and S, Se are present in group VI. #b)# GaAs and GaP are III-V semiconductors, while CdS and CdSe are II-VI semiconductors.

03

Suggesting other compound semiconductor compositions

To suggest other compositions of compound semiconductors, we can combine elements from groups that are neighbors to Si and Ge, i.e., II-VI or III-V: - Indium phosphide (InP): In (indium) belongs to group III, and P belongs to group V; thus, forming a III-V compound semiconductor. - Aluminium antimonide (AlSb): Al belongs to group III, and Sb (antimony) belongs to group V; thus, forming a III-V compound semiconductor. - Zinc sulfide (ZnS): Zn (zinc) belongs to group II, and S belongs to group VI; thus, forming a II-VI compound semiconductor. - Zinc selenide (ZnSe): Zn belongs to group II, and Se belongs to group VI; thus, forming a II-VI compound semiconductor. #c)# Some other possible compound semiconductor compositions are InP (III-V), AlSb (III-V), ZnS (II-VI), and ZnSe (II-VI).

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