Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.

The room-temperature absorption and uncorrected emission spectra ofinitially prepared InP QDs with a mean diameter of 32 A˚ are shown in Fig. 2.The absorption spectrum shows a broad excitonic peak at about 590 nm and ashoulder at 490 nm; the substantial inhomogeneous line broadening of theseexcitonic transitions arises from the QD size distribution. The transitions areexcitonic because the QD radius is less than the exciton Bohr radius. Thephotoluminescence (PL) spectrum (excitation at 500 nm) shows two emissionbands: a weaker one near the band edge with a peak at 655 nm, and a second,stronger, broader band that peaks above 850 nm. The PL band with deep redshiftedsubgap emission peaking above 850 nm is attributed to radiativesurface states on the QDs produced by phosphorous vacancies [9,12].The room-temperature absorption spectra as a function of QD sizeranging from 26 to 60 A˚ (measured by TEM) are shown in Fig. 3; the red-Figure 2 Absorption and emission spectra at 298 K of untreated 32-A˚ InP QDs.(From Ref. 9.)Copyright 2004 by Marcel Dekker, Inc. All Rights Reserved.