Resonant Raman scattering probe of alloying effect in ZnMgO thin films

We have presented a detailed resonant Raman scattering investigation for the alloying effect in hexagonal Zn1-xMgxO (x <= 0.323) thin films grown by pulsed laser deposition. Alloy-induced longitudinal optical (LO) phonon resonance effect has been achieved from the Raman peak shift, lineshape, and intensity through changing the Mg composition and temperature to tune the ZnMgO bandgap. By the aid of theoretical analysis combining with the extrinsic Frohlich interaction mediated via a localized exciton, we demonstrate the pronounced outgoing resonance behavior for the LO phonons in ZnMgO, where the localized exciton due to alloy disorder dominates the resonance processes. (C) 2008 American Institute of Physics.