Photoluminescence investigation of InGaAs-InGaAsP multiquantum wells for laser devices

The photoluminescence (PL) properties of InGaAs-InGaAsP multiquantum well (MQW) structures for laser devices emitting in the ~1.55 μm wavelength region are discussed. Different PL techniques, such as spectral analysis for studying interface quality, spatially and spectrally resolved cartography measurements for recording peak intensity distributions, and large-area topography for defect detection, have been applied to monitor the properties of as-grown and processed structures. After establishing the good quality of the as-grown structures, it is shown that the second epitaxial growth sequence or re-growth for realizing laser devices is a crucial processing step and that its optimization should take into consideration the doping level of Zn impurity