Current Components

Use the Checkboxes on top of the Applet for control.

Electron Leakage (drift) Current

Turn off all Checkboxes except for leakage and electron.
If no dots flow, the clik the checkboxes on & off a few times.
Observe the blue dots that flow down the potential hill. These blue dots are the leakage electrons.

Hole leakage (drift) Current

Repeat the above for leakage and hole,
Observe the red dots that flow up the potential hill. These red dots are the leakage holes.

Electron Injection (diffusion) Current

For injection and electron,
Observe the blue dots that move horizontally from n-type to p-type. These are the injection electrons.

Hole Injection (diffusion) Current

For injection and Hole,
Observe the red dots that flow in the valence band, horizontally. They move from p-type to n-type.

Electron Recombination Current

Turn off all Checkboxes except for recombination and electron.
Observe the blue dots that flow from the conduction band to the valence band, vertically.
Change doping level of Na, see what changes to the initial height of the minority carrier density, diffusion length, and the length which recombinaion can occure. Note that the diffusion length and the length which recombination can occur decreases as the doping level increase.

Hole Recombination Current

Turn off all Checkboxes except for recombination and hole.
Observe the red dots that flow from the valence band to the conduction band, vertically.
Change doping level of Nd, see what changes to the initial height of the minority carrier density, diffusion length, and the length which recombinaion can occure. Note that the diffusion length and the length which recombination can occur decreases as the doping level increase.

At zero applied bias (click the reset button at bottom), the magnitudes are such that

electron injection current = electron leakage current.
hole injection current = hole leakage current.
Since they flow in opposite direction, the total electron current is zero and the total hole current is zero. Therefore the total current (electron current + hole current)
Can you verify #4 in the applet ?

NOTES

In the energy band diagram, electron energy increases as you go up. But hole energy increases as you go down. Therefore, both leakage currents (electrons and holes) flow in the direction of decreasing energy.