Temperature-dependent luminescence of InP quantum dots coupled with an InGaP quantum well and of InP quantum dots in a quantum well

Abstract

We report the temperature-dependent cathodoluminescence (CL) properties of (1) InPInAlGaP quantum dots (QDs) coupled to an InGaP quantum well (QW) through a thin InAlGaP barrier (or simply QW+QD), (2) InP QDs grown directly in the well (DWELL), and (3) a reference sample InPInAlGaP QDs. We found that with an increase in temperature, the CL peak of the reference sample shows a large redshift compared with the band gap shift of InP. This large redshift is due to the thermally activated carriers transferred from small QDs to large ones. Within the temperature range studied, this redshift of the CL peak is much larger in DWELL but is much smaller, and in some temperature range, the energy of CL peak is independent of temperature for QW+QD samples. We believe that the temperature-insensitive emission energy observed in QW+QD is caused by (1) thermalization of hot carriers in the QW and (2) nonuniform tensile strain in the QW created by the varying sizes of QDs on top of the QW. © 2005 American Institute of Physics.