Photoconductivity decay in metamorphic InAsP/InGaAs double heterostructures grown on InAS_yP_(1-y) compositionally step-graded buffers

摘要

Lattice-mismatched InAs_(0.32)P_(0.68)/In_(0.68)Ga_(0.32)As/InAs_(0.32)P_(0.68) double heterostructures (DH) were grown on compositionally graded InAS_yP_(1-y)/InP substrates by solid-source molecular-beam epitaxy (MBE) out to a misfit of ～1%. The kinetics of carrier recombination were investigated in the nearly totally relaxed MBE-grown DH structures using photoconductivity decay (PCD) measurements. High minority carrier lifetimes of 4-5 μs close to the radiation limit were measured, indicating the ability of MBE-grown InAS_yP_(1-y) buffers in achieving high-electronic-quality, low-band-gap mismatched InGaAs layers. Analysis suggests that very low interface recombination velocities are achieved. A photogenerated carrier diffusion model is presented to explain the initial nonlinear decays observed in PCD data for these heterostructures.