Preface

Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard and brittle crystalline solid with a blue-grey metallic luster, and it is a tetravalent metalloid and semiconductor.

Most silicon is used commercially without being separated, and often with little processing of the natural minerals. It has many applications in the manufacturing technology of microelectronic components, integrated circuits, and photovoltaic generators. Circuit complexity and higher degrees of integration of components require constant improvement and control of the properties of silicon. Elemental silicon also has a large impact on the modern world economy.

We wish to thank everyone who showed us patience and understanding and offered us help during the intensive phase of creating this book.

> **Dr. Beddiaf Zaidi**  Department of Physics, Faculty of Material Sciences, University of Batna 1, Batna, Algeria

> > **Dr. Slimen Belghit** University of Batna 1, Batna, Algeria

**1**

**Chapter 1**

**1. Introduction**

apart from oxygen.

**2. Energy bands**

**3. Basic material**

the bands get overlapped (**Figure 1**).

multistage processes must be implemented.

Introductory Chapter: Silicon

Silicon (Si) is a member of Group 14 (IVA) in the periodic table of elements. Si is also part of the carbon family. This family elements include C, Ge, Sn, and Pb. Silicon is a metalloid, one of only a very few elements that have properties of both metals and non-metals. Si is the second most abundant element in the Earth's crust,

Silicon is a semiconductor whose number of free electrons is less than conductor but more than that of an insulator. Two kinds of energy band which are conduction and valence. Series of energy levels having valence electrons forms valance band in solid. At 0°K, the energy levels of valence band are filled with electrons. This band contains maximum of energy when the electrons are in valence band. Conduction band is the higher energy level band, which is the minimum of energy. Conduction band is partially filled by the electrons, which are known as the free electrons as they can move anywhere in solid. These electrons are responsible for current flowing. There is a gap of energy. The difference between the conduction band and valence band is called energy gap. For semiconductors, the gap is neither large nor

Apart from the oxygen, silicon is most commonly occurring element on the Earth. Silica is the dioxide from silicon and occurs mostly as quartz. Its synthesis has been familiar for many decades. It is extracted from (mainly) quartzite reduction with carbon in an arc furnace process [1]. The pulverized quartz and carbon are put in a graphite crucible. An arc causes them to melt at approximately

SiO2 + 2C ➔ Si + 2CO(g) (1)

The liquid collected at the bottom of crucible can then be drawn off. Its purity

can be approximately 97.9%. This is called metallurgic grade silicon (MG-Si). However, for silicon to be used in the semiconductor industry, the impurities must be removed almost completely by further processes. For such a high purity grade,

1800°C. Then, the reduction process takes place according to the formula:

*Beddiaf Zaidi and Slimen Belghit*
