Why does the LED structure favorizes p-type semiconductor?

[Buiosu]

Why does the LED structure "favorizes" p-type semiconductor?

Hi all,

At first I apologize if my English makes this post harder to understand ;).

I am trying to figure out why there is always P-type semiconductor flashing outside in LEDs, both planar and edge ones - P-type region is the active region, why not N-type sometimes?
Radiative recombination occurs within the area that overlaps both semiconductors - why then p-type is better to be exposed?

I am thinking if it has something to do with direct/indirect band gap or maybe quantum efficiency of p/n semiconductors - but if there is any n-type semiconductor with direct band gap then I'm wrong.

Regards.

 

[BigJDubs]

The LED structure "favors" p-type semiconductor due to the physics of how light is emitted from a diode. When the electrons in the n-type semiconductor recombine with the holes in the p-type semiconductor, they release their energy in the form of photons. The energy of these photons is dependent on the bandgap of the materials used, and since the bandgap of p-type semiconductors is typically lower than that of n-type semiconductors, the photons released are more likely to be in the visible spectrum. This makes p-type semiconductors more efficient at producing visible light compared to n-type semiconductors, which is why they are typically used in LED structures.