Dear Romana Yousuf ,

In general defects can be fully characterized by their energy level Et in the energy gap either with reference to Ev,Ec orEi, the capture cross-section of holes and electrons and the density Nt. Et can be any where in the energy gap but the most effective ones lie near the mid gap.

For the trap effects please see the book chapter:Chapter Solar cells and arrays: Principles, analysis and design

please refer to this paper in the link to see the characterization of the defects:Article On the Investigation of Interface Defects of Solar Cells: Le...

Best wishes

@A A Zekry sir

Thank you for your kind response...

Sir, Can you pls help me in understanding the following:

1. I have studied two cases in defect analysis:

a) when energetic distribution is of CB tail type and reference energy level is below CB.

b) when energetic distribution is VB tail and reference energy level is above VB

For both the cases I varied the defect levels from CB min to VB max i.e within bandgap and plotted the graph.

I hav found that the graph for CB tail is more sensitive than VB tail.

Is this result correct or should I get the similar graph for both...

What makes CB tail more sensitive than VB tail graph???

Kindly suggest...

2. Whenever tails protrude towards the band gap. How much extension is allowed??? Can we allow any tail to protrude towards the other band edge...

I welcome suggestions from any member of RG ..

THANKS & REGARDS

Romana

thank you proff.Dr .Abdelhalim Abdel Naby Zekry introduce good discussion

Thank YOU Dr. Hadi for your complement!

Dear Romana,

What do you mean with the reference energy level? Do you mean the Fermi-level.

What do you measure? Do you measure the recombination rate or the lifetime?

What do you mean with the band tails?

In the literature you can fined a trap distribution a saddle with the minimum at the middle of the bandgap and maximum at the band edges. Something like what do you investigate.

As a conceptual answer, the recombination rate via a tarp in the energy gap is determined by the Shockley Read Hall recombination theory.

This theory shows that the recombination rate will be highest when the trap lies in the mid band.

I would like that you follow the book: Book Electronic devices with physical insight

This theory is explained in the book.