Introduction to Semiconductors, PN Junctions and Bipolar Junction Transistors

This online course is the first part of the Principle of Semiconductor Devices Professional Certificate Program.

In this course, we will start with the fundamental concept of semiconductors as a tutorial for doping and the formation of PN junctions. Major and minority carrier currents in PN junctions under forward bias and reverse bias will be explained based on drift and diffusion physics. The course will further explain the operating principle of photodiodes, solar cells, light-emitting diodes (LED) and metal-semiconductor contact.

As an extension of PN junction theory, the concept will be extended to form bipolar junction transistors (BJT). The different operation modes of a BJT, including forward active, reverse active, saturation and cutoff under common emitter mode, will be introduced. The gain and amplifying mechanism of a BJT will be explained based on the carrier actions. The detailed behavior of the BJT will be summarized by a circuit model.

Week 1: Intrinsic semiconductor materials
Introduction to the energy band diagram of a crystal and calculating the carrier concentration in the material.

Week 2: Doping and PN junction formation
The effect of doping and the formation of PN junctions.

Week 3: Current-voltage characteristics of PN junction diodes
Current-voltage characteristics and detailed carrier actions in a PN junction diode.

Week 4: Real PN junction characteristics, its model and design
The characteristics of real PN junction diodes, the charge and capacitance models, and the design strategy.

Week 5: PN junction optical properties and metal-semiconductor contacts
The optical responses of the PN junction; the working principles of optical detection, solar cells and LEDs; and the metal-semiconductor contacts.

Week 6: Basic operation of Bipolar Junction Transistor
Introduction to bipolar junction transistors, I-V characteristic and non-ideal effects.

Week 7: Real Bipolar Junction Transistor structures, switching characteristics and model
Switching characteristics of the Bipolar Junction Transistor, it circuit model and design strategy.

Week 8: Final Exam