Optical properties of Nd-doped InGaAsP epilayers

The optical properties of Nd-doped InGaAsP epilayers grown by liquid phase epitaxy (LPE) have been studied by photoluminescence and Raman scattering. The full width at half maximum (FWHM) of the photoluminescence peak has been found to decrease as the doping amount of Nd element increases. The narrowest value of the FWHM of PL peak is 7.5 meV, which is smaller by about 46% than that of the undoped InGaAsP and better than previous reports on similar composition layers. Using a spatial correlation model, we found that the asymmetric broadening of the lineshape of the Raman signal is not influenced by the Nd doping. We hence conclude that the introduction of the Nd element can greatly reduce the residual impurities of LPE-grown layers, but the Nd element is not incorporated into the epitaxial layers during the purification.