GRAIN SIZE OF LEAD SELENIDE ELECTRODEPOSITED ONTO INP FOLLOWED BY PHOTOLUMINESCENCE OF THE INP SUBSTRATE

摘要

Lead selenide presents large quantum size effects. An increase in the effective bandgap appears for crystallite sizes as large as 40 nm leading to a strong shift towards higher photon energies of the absorption coefficient curve. This compound was grown by electrodeposition under a fixed potential onto n-InP substrates. The solution composition and the choice of the cathodic potential control the crystallite size. The intensity variation of the photolmninescence provided by the InP substrate has been used as an in situ probe to follow the deposition process. The photoluminescence signal depends on the modification of the optical parameters of the PbSe/InP interface. The absorption threshold was found to be shifted from 0.28 eV in between 0.8 and 1.0 eV, indicating quantum size effects for crystallite size evaluated to be in the range 10 to 20 nm. Results are in good agreement with the deposits characterization by IR-NIR-VIS spectroscopy and TEM observations.