Physics of the Diode
To the reader: Please read the “Introduction of the Physics of Electrical Circuits” written by Robert de Hilster to learn the rules about The Particle Model.
A diode is a two-terminal electronic component that allows current to flow primarily in one direction, making it essential for controlling electrical circuits.
A diode symbol is shown in Figure 1.
The diode symbol has two sections. The positive terminal is shown with a triangle while the negative terminal is shown with a straight line. The diode conducts current in the direction of the triangle (PN). The diode blocks current in the reverse direction (NP). Electron flow moves in the opposite direction. Therefore, electron flow is in the (NP) direction while the electrons are blocked in the (PN) direction.
Figure 2 is the IV Curve of the Diode.
There are two knees on the IV Curve of the diode. The first knee is in the first quadrant and represents the forward bias or the conduction of current. The second knee is in the third quadrant and represents the reverse bias of the diode or the loss of conduction.
Standard Explanation of the Diode
A diode is defined as an electronic device that conducts electricity only in one direction. It consists of two terminals: the anode and the cathode. When the anode is at a higher voltage than the cathode (forward bias), the diode allows current to flow. Conversely, when the cathode is at a higher voltage (reverse bias), the diode blocks current flow.
Depletion Layer
Figure 4 explains the diode based on the size of the depletion layer. The depletion layer is neutral when there is no voltage applied. See Figure 4a. The depletion layer gets smaller when the diode is forward biased. A small depletion layer will allow the electron to flow through the diode. This explanation is based on charge. The Particle Model rejects charge and therefore rejects the concept of a depletion layer.
Explaining the Diode Using “The Particle Model (TPM)”
TPM does not use current to describe the physicality of the diode. ‘Current’ is the flow of holes and TPM does not find that very interesting. TPM used the flow of G1s (electrons with no charge) which are clearly physical.
Start with a few definitions:
- G1 particle replaces the electron but has no charge.
- G1 Gravity is the random flow of G1 particles around an object (Newtonian gravity).
- Steady stream of G1 particles is current (electron flow).
- G2 particles are the orbital of a subatomic atom.
- Random flow of G2 particles around an object is the source of G2 Gravity.
- Steady stream of G2 particles is the definition of F2 force.
A diode is a two-terminal electronic component that allows current to flow primarily in one direction (forward biased) and blocks current flow in the opposite direction (reverse biased). See Figure 5.
Doping
The diode has two regions. The P region with very few G1 Particles and the N region with many G1 particles. The ‘F2 Bal’ line is located where the number of G1s (red dot) above the line matches the number of G1s below the line. It is this imbalance that allows the diode to be used as a conductor or as a nonconductor.
Definition: F2 Force — G2 Particles organized around an object setting up F2 forces that push to the center of mass of the object.
The F2 force surrounds the diode from all directions. In most directions these forces balance out. The interesting direction is through the top and from the bottom. See Figure 5. As they move through the diode it sets a balance point where the F2 forces meet and balance.
Forward Biased — Conducting
The G2 force of gravity (F2) surrounds the diode in all directions. The diode is doped so that there are more G1s in the N region than in the P region. Because of this the diode is not balanced; the F2 force is equal at the blue line in Figure 5.
This offset is what gives the diode the ability to aid the forward current and block the reversed current. The F2 Balance explains the forward biased diode and is shown in Figure 5 in the vertical direction.
Figure 6 shows the G1 particle flow through the diode as red arrows entering the N Region. Even though there is very little open space the force is strong enough to accelerate the G1s through the N Region and to keep it going all the way through.
Reversed Biased — Nonconducting
Figure 7 shows the diode in the reverse biased mode. In this case the G1 particles enter the P region aided by the F2 force. The G1 particle accelerates until it hits the F2 Bal point. After the F2 Bal the opposing F2 force is very strong and slows the speed of the G1 particle. The strong F2 force prevents the G1 from passing all the way through.
What causes the diode IV curve to change direction at the knee?
Speed
When the forward IV curve reaches the knee, it changes direction. At this point the current also increases. An increase of the number of G1s flowing in the diode causes the F2 force around the diode to increase. This increased F2 force causes the G1s to increase their speed. The faster the G1s go, the more easily they pass through the diode. So, fewer G1s are lost and the voltage drop increases but at a slower rate.
The vertical IV curve in the first quadrant indicates that the G1s are moving faster; they cause less G1 loss (voltage loss) even though the current is increasing.
