Improved emission wavelength reproducibility of InP-based all MOVPE grown 1.55 micrometer quantum dot lasers

InAs quantum dots (QD) on InP emitting at 1.55 micrometer grown by using conventional MOVPE sources were investigated. Aiming at their implementation in 1.55 micrometer laser structures thermal stability of the QDs during growth of the upper cladding layer was found to be a severe problem most probably due to movement of growth constituents resulting in a marked blue-shift of the emission. This shift was systematically investigated using thermal treatment to simulate cladding growth. The strong dependence of the blue-shift on growth temperature (Tg) of the QDs is believed to be due to defects being incorporated during GalnAsP matrix deposition. The cause for the defects is assumed to be incomplete decomposition of the PH3 or reduced surface diffusion length at low Tg which support interdiffusion. Above Tg=510 deg C stable emission from the QDs independent of regrowth temperature in this range was observed. Application of a QD deposition temperature of 500 deg C results in laser structures with a QD density of 5-1010 cm-2. Excellent laser material quality characterized by Jth less-than 100 A/cm(exp 2) per QD layer was achieved. Entnommen aus <a_href="http://www.fiz-technik.de/db/b_tema.htm" target="_blank">TEMA</a>