Heterointerface optimization in InP based strained MQW laser structures using metalorganic growth technologies

Epitaxial growth of InP based strained MQW laser structures is studied for metalorganic vapor phase epitaxy (MOVPE) and metalorganic molecular beam epitaxy (MOMBE or CBE-chemical beam epitaxy). For a tensile barrier layer strain of |ε_B|⩾0.4% both in MOVPE and MOMBE, wavy MQW interfaces are observed in TEM along with a severe drop in photoluminescence (PL) intensity and an increase in PL FWHM (full width at half maximum) yielding a significant increase in threshold current density of broad area test lasers. Lateral thickness modulations appear to be much larger in MOVPE than in MOMBE. The V/III ratio appears to be a key parameter for the rate of wavy interface development, which is probably a consequence of surface selective growth. Flat interfaces require low V/III ratios, especially at high strain in the barrier layers resulting in a significant improvement in threshold current density