CL and EBIC analysis of a p(+)-InGaAs/n-InGaAs/n-InP/n(+)-InP heterostructure

A p(+)-In0.56Ga0.44As/n-In0.56Ga0.44As/n-InP/n(+)-InP heterostructure has been realized by chemical beam epitaxy and characterized using cathodoluminescence (CL) and electron beam-induced current (EPIC) techniques. These techniques allowed the visualization, location and density measurement of a misfit dislocation network due to the compressive strain between the epitaxial layers. The structure was found to be partly relaxed with the dislocation network located in the InP buffer under the hetero-interface and with a dislocation density between 1.9 x 10(7) and 5.3 x 10(7) cm(-2) according to the area chosen; no threading dislocations were found in the InGaAs layer, which demonstrates the efficient role of the buffer as a dislocation barrier. Moreover, some important diffusion-recombination (DR) parameters, such as the minority carrier diffusion length, and the surface and interface recombination velocities, have been evaluated throughout the whole structure by fitting a CL theoretical model to experimental measurements. Photon recycling in the highly doped substrate has been evidenced by spectroscopic and semiquantitative measurements.