Carrier dynamics in Ga(NAsP)/Si multi-quantum well heterostructures with varying well thickness

• Time-resolved photoluminescence measurements in Ga(NAsP)/(BGa)(AsP)/Si MQWHs.
• The impact of the QW thickness on the optical properties and carrier dynamics.
• A shortening in the PL decay time with increasing QW thickness.
• An increasing number of defects in the QW material for broader QWs.
• A strong dependence of the PL decay time on the emission energy at low temperatures.

Time-resolved photoluminescence (TR-PL) measurements have been performed in Ga(NAsP)/(BGa)(AsP) multi-quantum well heterostructures (MQWHs) with different well thicknesses. The studied structures have been pseudomorphically grown on Si substrates by metal organic vapor phase epitaxy (MOVPE) with an N content of about 7%. Experimental results reveal a shortening in the PL decay time with increasing QW thickness, meanwhile, accompanied by a decrease in the PL intensity. We attribute this behavior to an increasing non-radiative recombination rate for broader QWs which arises from an increasing number of defects in the QW material. The emission-energy distribution of the PL decay time is studied at various temperatures. The PL decay time strongly depends on the emission energy at low temperatures and becomes emission-energy-independent close to room temperature. This is discussed in terms of the carrier localization in the studied structures.