InAsyP1−y metamorphic buffer layers on InP substrates for mid-IR diode lasers

The defect-trapping effectiveness of an InAsP metamorphic buffer layer (MBL) design was investigated by studying the light-emission characteristics of InAs quantum wells grown on the MBL, along with structural characterization through SIMS and TEM measurements. Using a fixed recipe for the MBL, several separate confinement heterostructures (SCHs) were studied using 8-band k.p simulations, HRXRD, SEM, optical microscope and variable-temperature photoluminescence. Room temperature PL was observed at wavelengths near 3 μm, although the PL intensity drops significantly for samples with wavelengths longer than 2.85 μm. Laser operation was achieved at 77 K at a wavelength of 2.45 μm and threshold as low as 290 A/cm2.