Semiconductor Fundamentals Unit 1 – Introduction to Semiconductors
Exercise 1 – Semiconductor Component Identification
EXERCISE OBJECTIVE
When you have completed this exercise, you will be able to identify various semiconductor
devices. You will verify your knowledge by locating diodes and transistors on the
SEMICONDUCTOR DEVICES circuit board.
DISCUSSION
- Diodes and transistors are the two classes of semiconductors covered in this exercise.
- Diodes are generally constructed of germanium or silicon and consist of only one PN
junction. - Diodes are constructed with an anode (positive, P-type material) and a cathode (negative, N-
type material). - Schematic diagrams for common diodes, LEDs, and zener diodes are illustrated in the
exercise. Common types of diode packaging are shown, also. - Diodes are usually identified on schematic diagrams by the letters CR followed by a number.
For example: CR12. - Specialized diodes, designed for specific tasks, include the Zener diode, which can maintain
a constant voltage, and the Light Emitting Diode (LED), which emits light under specific
circumstances. - Transistors belong to two major families, Field-Effect Transistors (FET) and Junction
Transistors (JT). Only junction transistors, also called bipolar transistors, are discussed in this
course. - Transistors have two PN junctions; therefore, they have three regions. Each region consists
of either N-type or P-type material. The three regions can be formed two ways: as P-type
material sandwiched between N-type material (NPN) or by N-type material sandwiched
between P-type material (PNP). - Junction transistors have a terminal (lead) connected to each of the three regions. The center
region is designated the base. The outer regions are designated emitter and collector,
respectively. - Schematic diagrams for PNP and NPN type junction transistors are illustrated in the exercise.
Transistors are usually identified by the letter Q, followed by a number, on circuit diagrams.
For example: Q2.