Carrier dynamics in linearly and step graded bandgap Zn1-xCdxO structures

摘要

We report on the time-resolved photoluminescence studies of step-like and linearly graded bandgap ZnCdxO (x?=?0%?–?60%) structures. The key carrier transport properties essential to the concept of variable bandgap absorbers are addressed, including radiative and nonradiative lifetime, diffusion and drift in the built-in field, and surface and interface recombination. A comprehensive set of depth-resolved recombination time parameters is presented revealing the individual roles of internal electric fields, built-in strain, and resultant polarization fields as well as of misfit strain at interfaces on the carrier dynamics.