ECE492 Section 1 Notes

Welcome! Notes for Spring 2022 Electronic Circuits course. Will make this more pretty as things evolve.

My goal is to make Electronic Circuits so easily digestible, you could teach a middle schooler. We'll see if this works.

Prologue

Hey how are you. I will insert something here later. :)

Section 1.1

We first need to consider the following materials:

• Conductors
• Insulators
• Semiconductors

Consider the concept of the charge for Oxygen (O):

• 8 protons around the nucleus
• 8 electrons (two on the inner orbit, 6 on the outer orbit).

Let's look at the outer most orbit in context with a conductor:

• There are two bands: valency and conduction.
• Electrons are always in the valency band.
• In between, there is an energy gap, which is approximately 0 (meaning electrons can move freely between valency band and conduction band).
• That is the reason why conductive materials act as they do.

Let's look at the outer most orbit in the context of insulators:

• There are two bands: valency and conduction.
• Electrons are always in the valency band.
• In between, there is an energy gap, which is very high (meaning electrons have a very hard time moving between the valency band and conduction band).
• That is the reason insulators, are well, insulators (or their property is insulative).

Let's look at the outer most orbit in the context of semi-conductors:

• There are two bands: valency and conduction.
• Electrons are always in the valency band.
• In between, there is an energy gap, which is exactly 1.12eV (1eV = 1.602 * 10^-19J).
• Once electrons are in the conduction band, the semi-conductor will act as a conductor.

This entire class is based on semi-conductor materials.

What is a semiconductor?

It sometimes allow current, and sometimes it doesn't.

Semi-conductors only have 4 electrons in its outermost orbit.

• Carbon
• Silicon
• Germanium
• Lead

What's the best two?

• Silicon and Germanium

Consideration of Silicon:

• Silicon will acquire other silicon atoms to form a covalent bond.

Now let's take a Silicon atom:

• Take a pure silicon atoms and put energy to them: go from insulator to conductive properties, and electrons from the furthest orbit detach and jump to another position.
• When electrons detach, it leaves a hole where it once was, that is viewed as a positive charge for clarity.

Doping: Adding impurity to a pure semiconductor material.

• Tri-Valent Impurity: majority of "holes" (positive charge), also know as P-type semiconductor.
• Penta-Valent Impurity: majority of electrons, also known as N-type semiconductor.

Let's take Aluminum for Tri-Valent example:

• Pair the Aluminum with Silicon atoms, knowing that Aluminum has an outer electron count of 3.
• Silicon will be bounded to the three outer Aluminum electrons, but 1 Silicon will be left.

Let's try Phosphorous for Penta-Valent example:

• Pair Phosphorous with Silicon atoms, knowing that Phosphorous has an outer electron count of 5.

Assignment 1.1

We'll take this $x_{3}={\frac {9}{3}}$ and plug it into $2x_{2}+x_{3}=5$ to find x₂:

${\begin{aligned}2x_{2}+x_{3}=5\\x_{3}={\frac {9}{3}}\\{\text{Plug in }}x_{3}={\frac {9}{3}}{\text{ into }}2x_{2}+x_{3}=5{\text{:}}\\2x_{2}+{\frac {9}{3}}=5\\2x_{2}=2\\x_{2}=1\end{aligned}}$