The effect of barrier composition on the vertical carrier transport and lasing properties of 1.55-/spl mu/m multiple quantum-well structures

In this paper, the effect of barrier bandgap and composition on the optical performance of 1.55-/spl mu/m InGaAsP/InGaAsP and InGaAsP/InGaAlAs multiple quantum-well structures and Fabry-Perot lasers is evaluated experimentally. Direct vertical carrier transport measurements were performed through strain-compensated multiple quantum-well (MQW) test structures using femto-second laser pulse excitation and time-resolved photoluminescence up-conversion method. MQW test structures were grown with different barrier composition (InGaAsP and InGaAlAs) and barrier bandgap (varied from /spl lambda//sub g/= 1440 to 1260 nm) having different conduction band /spl Delta/E/sub c/ and valence band discontinuity /spl Delta/E/sub v/, while keeping the same InGaAsP well composition for all the structures. The ambipolar carrier transport was found to be faster in the structures with lower valence band discontinuity /spl Delta/E/sub v/. Regrown semi-insulating buried heterostructure Fabry-Perot (SIBH-FP) lasers were fabricated from similar QWs and their static light-current-voltage characteristics (including optical gain and chirp spectra below threshold) and thermal characteristics were measured. Lasers with InGaAlAs barrier showed improved high-temperature operation, higher optical gain, higher differential gain, and lower chirp, making them suitable candidates for high-bandwidth directly modulated uncooled laser applications.