I have fabricated ZnO based p-n homojunction diode with turn-ON around 4V current at 80mA. PL spectra shows strong emission in UV region (375 nm). But I am unable to view any UV/visible emission during electroluminescence study? What could be be the probable reasons? The device structure is as follows:
Do you expect a large number of defects in your structure? Could it be that the non-radiative recombination channels are not saturated in your case (i.e. the non-radiative centers are numerous) and all the injected carriers go to these non-radiative reeombination paths?
How do you know that your structure is a pn-junction? Rectifying behavior is not enough to prove that, as you will observe recitification also if the "p-type" layer is just highly resistive. Main point: how do you know that your p-type layer is actually p-type? The apparent impossibility of obtaining p-type ZnO is one of the major difficulties in The fabrciation of ZnO-based devices.
Dear Prof.Filip Tuomisto.,
Thanks for your kind reply. The above structure is p-i-n junctions (since ZnO p-n homojunctions didnt showed rectifying behavior, we have deposited a thin i-ZnO layer that will act as an interface/active layer). We have confirmed the p-ZnO by Hall effect measurement system (But I accept Hall study is not advisable for p-ZnO confirmation).
1) Is there any fault in the device structure?
2) Apart from Hall measurement is there standard experiment to confirm the p-ZnO?
Expecting for your reply
Dear Prof. Vesselin Donchev.,
Thanks for your suggestions. Yes, the non-radiative recombinations may also be a reason. I will check for it once again in my future diode fabrication.
Thank you once again.
Dear Prof. Abderrahmane Kadri.
Thanks a lot for your kind reply. I do accept with all your suggestions. Especially as you have suggested the device structure should be inverted. I will deposit the other way and test the results. We are depositing our ZnO films by spray pyrolysis method. I will go through papers which you have sent to me.
Thank you once again for your kind time and attention.
-Amir
Dear Amiruddin Rafiudeen ,
Sure I came very late to this question. Hope you succeeded to get electroluminescence from you structure.
It is normal to get photoluminescence from the any homogeneous semicondcutor.
In order to get electroluminescence you must have a diode structure.
The easiest method is to measure the I-V characteristics both in the forward and and in reverse direction. The type of conduction can be easily determined by the hot probe method.
For more information please follow the link: Article Fabrication of ZnO Nanorods p-n Homojunction Light-Emitting ...
Best wishes
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