Fig. 7
From: Uprooting defects to enable high-performance III–V optoelectronic devices on silicon
Effect of reducing dislocations on optical properties. Monte-Carlo simulations using CASINO software of the electron interaction volume, and planar cathodoluminescence (CL) micrographs of a 300 nm-thick GaAs layer grown on bulk Ge substrate, Ge/Si substrate, and the NVS at 5 keV (a–d) and 20 keV (e–h), respectively. The color scale bar in a, e shows the electron concentration. The CL micrographs in b–h show the emission and the recombination behavior at the surface (5 keV) and in the bulk (20 keV) of GaAs on each substrate. Scale bars 3 µm. Room temperature cathodoluminescence spectra recorded from i GaAs/Ge, j GaAs/Ge/Si with a TD density of ~107 cm−2 and k GaAs/NVS with a TD density of ~104 cm−2, at 5 and 20 keV. CL measurements confirm that the dislocations were effectively blocked from propagating using nanovoids, which is reflected by an enhancement of the emission efficiency of GaAs grown upon the NVS
