We show that the cathodoluminescence (CL) properties of InP quantum dots (QDs) grown on In0.5Al0.5P matrix layers, lattice-matched to (001) GaAs substrates, can be greatly improved by introducing silicon delta doping in the layer adjacent to the QDs. Under optimized conditions, the room-temperature CL intensity of QDs can be improved by ∼ 16 times. We speculate that the increased CL intensity is caused by the efficient capture of electrons from the reservoir of the delta-doped layer into the QDs, which, to some extent, counterbalances the thermal escape of electrons from the QDs. A temperature-dependent CL study of InP QDs grown without Si delta doping shows a quenching of the CL at high temperatures, which supports the unipolar escape of electrons from QDs, while delta-doped QDs show an anomalous behavior. The QD integrated CL intensity increases with temperature and then decreases after 200 K. This anomalous behavior is interpreted as caused by competition between two processes: (1) thermal activation of carriers out of the potential well introduced by delta doping and then capture by QDs, which enhances the CL intensity; and (2) quenching of the CL due to thermal activation of carriers out of the QDs. © 2003 American Institute of Physics.