- #1
EmilyRuck
- 136
- 6
Hello!
Double heterostructures are used in LEDs and lasers to provide both the confinement of the charge carriers and the confinement of the generated light.
This image is a comparison between a homojunction and a heterojunction.
As regards the unbiased junctions, when the n region and the p region come into contact, the electrons of the n region diffuse in the p region despite the higher energy values of the conduction band.
Heterojunctions are built to confine the charge carriers; the central region (which will be the active region) has the conduction band limit which is lower than the conduction band of the left and right regions; the valence band limit is instead higher than the "neighbour". In the image, an electron from the right region could diffuse into the central one; but what can certainly prevent the electrons to diffuse from the central region to the left one, "climbing" and following the conduction band?
In a pn traditional junction, electrons can climb bands as written before; why should this case be different?
Double heterostructures are used in LEDs and lasers to provide both the confinement of the charge carriers and the confinement of the generated light.
This image is a comparison between a homojunction and a heterojunction.
As regards the unbiased junctions, when the n region and the p region come into contact, the electrons of the n region diffuse in the p region despite the higher energy values of the conduction band.
Heterojunctions are built to confine the charge carriers; the central region (which will be the active region) has the conduction band limit which is lower than the conduction band of the left and right regions; the valence band limit is instead higher than the "neighbour". In the image, an electron from the right region could diffuse into the central one; but what can certainly prevent the electrons to diffuse from the central region to the left one, "climbing" and following the conduction band?
In a pn traditional junction, electrons can climb bands as written before; why should this case be different?