Excitonic electroluminescence at room temperature in an (In,Ga)As multiple-quantum-well diode

Electroluminescence (EL) spectra of an In(0.15)Ga(0.85)As/Al(0.15)Ga(0.85)As multiple-quantum-well p-i-n diode measured at 15-300 K are dominated by the ground heavy-hole exciton transition, as assigned from coincidence to the leading exciton resonance absorption energy. Although most of excitons thermally dissociate into free carriers populated up to the first excited confinement states at room temperature, radiative recombination is strongly enhanced at the exciton states. Simulated EL spectra based on the excitonic absorption spectra rigorously reproduce all of the excitonic EL features superposed on the exponentially tailing emission at the continuum states, showing coexistence of excitons and free carriers at room temperature. (C) 2010 American Institute of Physics. [doi:10.1063/1.3464559]