Say we observe yellow and blue luminescence in GaN, and these defect peaks are always broader than the BE peak. What factors contribute to defect peak broadening? Please help me list out such factors with reasoning.
I think this problem relate to the additional energy level.
For example, surface trap state could create interstitial energy level in the middle of forbidden band. Without trap state, the energy is hv1. With trap state, the luminescence process would become hvt+hv2 = hv1. v1 quite close to v2 would lead to broadening.
In addition, some doped elements may change the shape of band structure which also contribute to the light.
Bansi Lal sir thanks for your reply. Here I am looking for reason for broadness of the defect peak itself and not the band edge peak. Request you to provide some inputs in this context. Thanks in anticipation.
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