Electronics I Essentials

By The Editors of REA

REA’s Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Electronics I covers fundamentals of semiconductor devices, junction diodes, bipolar junction transistors, power supplies, multitransistor circuits, small signals, low-frequency analysis and design, audio-frequency linear power amplifiers, feedback amplifiers, and frequency response of amplifiers.

• Language: English
• Publisher: Research & Education Association
• Release date: Jan 1, 2013
• ISBN: 9780738671987

Book preview

Preparation

CHAPTER 1

FUNDAMENTALS OF SEMICONDUCTOR DEVICES

1.1 CHARGED PARTICLES AND THE ENERGY GAP CONCEPT

The electron:

Negative charge = 1.60 × 10-19 coulomb

Mass = 9.11 × 10-31kg

Hole - In a semiconductor, two electrons are shared by each pair of ionic neighbors through a covalent bond. When an electron is missing from this bond, it leaves a hole in the bond, creating a positive charge of 1.6 × 10-19C.

The energy gap concept and classification of materials

(a) Energy levels

(b) Energy gap

(c) Semiconductor

(d) Conductors

Drift and the Dfffusion Current:

The diffusion current - The movement of charged particles due to a non-uniform concentration gradient.

The drift current - The movement of charges under the influence of an electric field.

1.2 FIELD INTENSITY, POTENTIAL AND ENERGY

Potential - The work done against an electric field in taking a unit of positive charge from point A to B.

Electric field intensity E:

Potential energy U (in joules) equals the potential multiplied by the charge q.

Potential-energy barrier concept:

The kinetic energy is at its maximum when the electron leaves electrode A.

At P, no kinetic energy exists; the electron can therefore travel up to a distance x0 from plate A.

The ev unit of energy: 1 ev = 1.60 × 10-19 J

1.3 MOBILITY AND CONDUCTIVITY

Mobility - When a metal is subjected to a constant E, a steady state is reached where the average value of the drift speed ν is attained. ν is proportional to E and is found by ν = μ E, where μ is the mobility of the electrons and where the electric field has small values.

ρ ≡ n · q is the charge density; ν is the drift speed of the electrons.