In an indirect bandgap semiconductor the radiative recombination is not very effective if the direct bandgap is say 50 meV up of the indirect one. So there is a competition between both radiative competition. If now there is an exciton forming at the direct band, the excitonic band is even closer to the direct band gap. I expect thus that the excitonic band behaves like the ground state.

This is an open reflection. Are my conclusions wrong? What kind of experiment/simulation could confirm that explanation. What do you think of the subject?