Type of solids and Crystal Lattices of Semiconductor

• Type of solids
• Crystal Lattices

• Introduction

The present age is being called the age of electronics.To be more precise, it can be callde the age of semiconductor electronics.From individual discreet devices to very large scale intregrated circuit, the progress in semiconductor technology has been stupendous.why do semiconductors behave the way they do is the topic of discussion in the chapter.

• Semiconductor Materials

Semiconductors com[rise a group of materials that have their electrical conductivities lying between metals and insulators.Furthermore, their conductivities can be modified by introducing controlled amounts of desirable impurities.Optical excitation and temperature also affect their electrical conductivity.Semiconductors are two types,namely,elemental semiconductors and compound semiconductor.

• Type of solids

there three types of solids depending upon the arrangment of the constituent atoms.the three types of crystalline/single, polycrystalline, and amorphous crystal solids.Atoms are arranged in a regular manner in a crystallin solid.A three -dimensional repetition of a certain basic pattern constitutes the solid.

What Is A Crystal Lattice?

A crystal lattice is the arrangement of these atoms, or groups of atoms, in a crystal. These atoms or groups of atoms are commonly referred to as points within a crystal lattice site. Thus, think of a crystal lattice site as containing a series of points arranged in a specific pattern with high symmetry. Note that these points don't tell you the position of an atom in a crystal. They are simply points 'in space' oriented in such a way to build a lattice structure.In chemistry, crystals are a type of solid material composed of atoms or groups of atoms that are arranged in a three-dimensional pattern that is very ordered. In a crystal, the groups of atoms are repetitive at evenly spaced intervals, all maintaining their orientation to one another. When you see the word 'symmetrical,' think about the perfect proportion and balance of these atoms in a crystal. Now that we know what a crystal is, and that is can be found inside our table salt and a sparkly diamond, let's look at crystal lattices.

Crystal Lattice Structure

As we look at the structure of a crystal lattice, keep in mind the patterns of arrangement of each point as well as their symmetry. Crystal lattice sites are only viewed microscopically and are invisible to the naked eye. In order to view these structures, we must take a crystal (solid object), place it under a microscope, and view the crystal lattice sites.

The structure of a crystal lattice is shown here. Recall that a crystal lattice is the arrangement of atoms in a crystal. This arrangement can be defined as the intersection of three parallel planes. So, if we slice this diagram into three parts you will see three different planes. When these planes intersect with one another, the result is a three-dimensional network that has faces. Think of each face as a box that is arranged in a parallel manner.

Diagram 1: Example of a Crystal Lattice Structure

Symmetric

You don't think I would forget about our friend symmetry, did you? Certainly not; in fact, these boxes (or faces) contribute to the symmetry of a crystal lattice structure. Each box contains the symmetry information required to ensure the crystal structure is translational.

Translational symmetry occurs when an object moves (or translates) at a certain distance in a certain location. For example, let's say you would like to build a patterned wood floor. You lay one style of wood down, diagonally, every 20 inches. This style of wood, in a particular pattern, has a certain distance (20 inches) and direction (diagonal).

Classification

Crystal lattices can be classified as either monatomic or polyatomic. This classification is based on the kind of atoms present in the face within a lattice structure. If there is only one type of atom used to make a face (or box), this is monoatomic. A polyatomic crystal lattice contains more than one type of atom used to make a face.

If we look at the crystal lattice structure of table salt (NaCl) - lattice (a), and a diamond - lattice (b), we will see they both have different lattice structures. One face in table salt is composed of points that are red and green. This means there is more than one type of atom present. Hence, this structure is polyatomic. With the diamond lattice structure, there is only one colored point (blue). This structure is monatomic.