Comparison of radiative and structural properties of 1.3 mu m InxGa(1-x)As quantum-dot laser structures grown by metalorganic chemical vapor deposition and molecular-beam epitaxy: Effect on the lasing properties

We have studied the radiative and structural properties of identical InxGa(1-x) As quantum dot laser structures grown by metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE). Despite the comparable emission properties found in the two devices by photoluminescence, electroluminescence, and photocurrent spectroscopy, efficient lasing from the ground state is achieved only in the MBE sample, whereas excited state lasing is obtained in the MOCVD device. Such a difference is ascribed to the existence of the internal dipole field in the MOCVD structure, induced by the strong faceting of the dots, as observed by high-resolution transmission electron microscopy.