Archive | Semiconductors

Semiconductors are materials which have electrical conductivities lying between those of good conductors and insulators. The resistivity of semiconductors varies from 10-5 to 104 ohm-m as compared to the values ranging from 10-8 to 10-6 ohm-m for conductors and from 107 to 108 ohm-m for insulators. There are elemental semiconductors such as Ge and Si which belong to IV group [...]

In this article we will discuss about the mechanism of current conduction in semiconductors. When no external field is applied to a semiconductor each carrier (electron or hole) moves in a random way owing to its thermal energy. The frequent change in direction of the path of the carrier occurs due to scattering by the vibrations of the lattice atoms [...]

In this article we will discuss about:- 1. Classification of pn Junctions 2. Characteristics of pn-Junction 3. Contact Potential 4. Breakdown in Diode. Classification of pn Junctions: A pn junction is a boundary between p-type region and n-type region of a single crystal semiconductor.  Based on the method of fabrication, the junctions may be classified as: 1. Grown Junctions 2. [...]

If a piece of conductor (metal or semiconductor) carrying a current is placed in a transverse magnetic field, an electric field is produced inside the conductor in a direction normal to both the current and the magnetic field. This phenomenon is known as the Hall Effect and the generated electric field as the Hall field. Consider a rectangular piece of [...]

Here is a list of some special pn junction diodes used in electrical appliances. 1. The Photodiode: We know that a built-in-voltage exists across a p-n junction, but this voltage cannot deliver current in an external circuit. However, if light is shown on the junction, there is current in the circuit. This effect is called the photovoltaic effect, and the [...]

In this article we will discuss about the commonly used semiconducting materials and their applications. Commonly Used Semiconducting Materials: 1. Germanium: Germanium, the material in which transistor action was first observed, is one of the most important semiconductors. The following points relate to germanium: i. It is a grey metallic looking material. ii. It is brittle and glass like in [...]

A biased pn junction is formed by connecting a source of dc potential across the p and n regions. When the positive terminal of a battery is connected to the p-side and negative terminal to the n side, the junction is said to be forward biased. If the terminals of the battery are reversed, i.e., the positive terminal is connected [...]

In this article we will discuss about:- 1. Introduction to Semiconductor 2. Classification of Materials in Terms of Energy Bands 3. Types 4. Classification of Elemental Semiconductors 5. Position of Fermi Level 6. Conductivity 7. Hall Effect 8. Merits 9. Formulated Materials 10. Applications. Introduction to Semiconductor: A semiconductor is defined as a material whose conductivity falls intermediate between that [...]