Microstructural analysis of Ga(NAs)/GaP heterostructures

We have investigated the microstructure of compressively strained Ga(NAs)/GaP quantum wells (QWs) with different N contents. This material system is a promising candidate for future integration of photonics on silicon substrates. N-induced microscopic strain fields are detected applying strain sensitive transmission electron microscopy dark-field (DF-TEM) imaging. Exceeding $7%$ of N concentration, we find a deterioration of the upper QW interface despite a reduction of the macroscopic strain for compositions with increasing N content. These nitrogen-induced structural characteristics of the ternary alloy are presumably correlated with the optical properties as observed by photoluminescence spectroscopy.