Effects of growth interruption on the optical and the structural properties of InGaN/GaN quantum wells grown by metalorganic chemical vapor deposition

Effects of growth interruption on the optical and the structural properties of InGaN/GaN quantum wells were investigated by using photoluminescence, transmission electron microscopy, optical microscopy, and high resolution x-ray diffraction. The InxGa1−xN/GaN (x>0.2) quantum wells used in this study were grown on c-plane sapphire by using metalorganic chemical vapor deposition. The interruption was carried out by closing the group-III metalorganic sources before and after the growths of the InGaN quantum well layers. The transmission electron microscopy images show that with increasing interruption time, the quantum-dot-like regions and well thickness decreased due to indium reevaporation or the thermal etching effect. As a result the photoluminescence peak position was blueshifted and the intensity was reduced. Temperature- and excitation-power-dependent photoluminescence spectra support the results of transmission electron microscopy measurements. The sizes and the number of V defects did not differ with the interruption time. The interruption time is not directly related to the formation of defects. The V defect originates at threading dislocations and inversion domain boundaries due to higher misfit strain.