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The 26th International Conference on Thermoelectrics, Jeju, Koréa, June 03-07, 2007

Quantitative nondispersive cathodoluminescence (CL) measurements and dispersive CL experiments are performed at room temperature on n(+)-InP substrates as a function of the accelerating voltage (Eo). The results are explained in terms of band-to-band recombination. The red shift of the CL spectrum observed when increasing Eo, as well as the large value of the measured diffusion length with respect to the radiative one are interpreted on the basis of a high efficiency of the photon recycling process.

We have determined the origin of the spatial luminescence fluctuations observed between the dark line defects present in tensile strained GaxIn1-xP/In1-xP/n(+)-InP heterostructures (Part I [F. Cleton et al. J. Appl. Phys. 80, 827 (1996)]). For that purpose, we have undertaken semi-quantitative and spectroscopic cathodoluminescence (CL) measurements on various specimens in areas exhibiting CL contrasts which could be as large as 80%. The analysis of the variation of the CL polychromatic signal with electron beam energy allowed us to get information on the diffusion-recombination (DR) parameters of the areas under study. From the correlation between the local relaxation level of these areas and their DR parameters, we can conclude that the variation of the misfit dislocations density at the GaxIn1-xP/InP interface is at the origin of the luminescence heterogeneities. We also demonstrate that recycling, by the GaxIn1-xP epilayer, of the photons originating from the heavily doped InP substrate, enhances the CL contrast between areas exhibiting different relaxation levels. (C) 1996 American Institute of Physics.

Two tensile-strained GaxIn1-xP / InP (001) heterostructures (with x = 6.5% and x = 11.2%) have been studied by TEM and cathodoluminescence. In both structures stacking faults and twins, located in the epilayer, have been found preferably along the [(1) over bar 10] direction whereas perfect misfit dislocations have been observed at the interface in the [110] and [(1) over bar 10] directions. The two types of structures differ about the nature of the misfit dislocations and about the thickness of the twins and this is thought to be due to the different stress relaxation amounts in these structures.