This is mostly a question for epi scientists working on phosphide- or arsenide-based LEDs.
Epi scientists who, like me, work on LEDs and lasers based on nitride materials (GaN, AlGaN, InGaN), tend to take as a given that their structure must have an EBL in order to have a good quantum efficiency. (Even though a few publications in the past few years have claimed the contrary.)
But is that also the case in similar structures made of different III-V compound materials? Or is it rather a characteristic of the nitrides, perhaps due to their strong polarization fields?
Note that I'm speaking about multiple-quantum-well structures, not double hetero-structures (which of course have an EBL!).
Could you please cite a reference from the literature that supports your answer?
I suggest that considering the photonic crystal based LEDs is useful for your research. In this structure, light extraction of the device is improved so the efficiency can be increased.
Dear Dario,
In the LEDs one would like suppress the back injection of electrons into the p-emitter and suppress the back injection of holes in the n-emitter. This is to avoid leakage of excess carriers from the wells to the end regions and thereby reduce the radiation efficiency. This suppression is accomplished by addition of barrier layers if they are naturally existing a consequence of energy band structure at the interface of the emitter regions to the well regions.
Best wishes
Electron and hole blocking layers are typically used in most opto-electronic devices, such as LEDs, solar cells, photo-detectors, etc., to optimize the efficiency or performance, regardless what the active material is, although they should be placed on different sides of the device, depending on the application. They are sometimes named differently, because the generally idea might be re-invented in one particular type of device without knowing it was already a common practice in other types of devices.
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