In‐situ observation of InGaN quantum well decomposition during growth of laser diodes

The deterioration of the InGaN active region of laser diode structures emitting around 440 nm is observed in‐situ during epitaxial growth and analyzed ex‐situ by cathodoluminescence spectroscopy and transmission electron microscopy. The growth conditions of the p‐layers on top of the InGaN active region are found to affect the homogeneity of the InGaN material properties which can be monitored by the in‐situ reflectance signal at 950 nm. The deposition of the p‐layers at 950 °C results in the formation of metallic indium platelets as well as voids changing the refractive index of the active region and thus the reflectance. A reduction of the p‐layer deposition temperature by 30 °C prevents this undesirable decomposition.