Investigation of long lifetimes in Cu(In,Ga)Se{sub 2} by time-resolved photoluminescence
- Institute of Physics, Martin-Luther-University Halle-Wittenberg, 06120 Halle (Germany)
The main objective of time-resolved photoluminescence (TRPL) is to characterize minority carrier recombination in semiconductors. However, trap states in the band gap can lead to artificially long decay times thus distorting the measured minority carrier lifetime. In this work, we propose to measure TRPL under elevated temperature and excitation in order to reduce minority carrier trapping. Taking three Cu(In,Ga)Se{sub 2} layers as examples, we show that the decay time decreases with increasing temperature—in accordance with simulations. Under increasing excitation, the decay time can become smaller due to trap saturation but also can become larger due to asymmetric hole and electron lifetimes. By comparison of simulation and experiment, we can find the energy, the density, and the electron capture cross-section of the trap which in the present example of Cu(In,Ga)Se{sub 2} films gives values of ∼200 meV, ∼10{sup 15 }cm{sup −3}, and ∼10{sup −13} cm{sup 2}, respectively.
- OSTI ID:
- 22482122
- Journal Information:
- Applied Physics Letters, Vol. 107, Issue 12; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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