Growth and characterization of InAsxP1-x/InP strained multiple quantum wells by gas source molecular beam epitaxy

InAsxP1-x/InP (10 period 50/100 Angstrom with x=0.25-0.79) pseudomorphically strained multiple quantum wells (SMQWs) were grown by gas source molecular beam expitaxy (GSMBE) at 470 degrees C and characterized by cross-sectional transmission electron microscope (XTEM), double crystal x-ray diffraction (DCXRD), and optical spectroscopy. The structural analysis demonstrates that excellent control of the sharp interface and limited As-P interdiffusion can be achieved by GSMBE growth. XTEM images of these SMQWs display no misfit dislocations, and DCXRD scans reveal high order superlattice satellite peaks. Photoluminescence (PL) and transmission measurements were performed for all SMQWs to evaluate crystal quality. Only slight degradation in luminescence was observed as the As composition increased. Based on the three-band Kane model which includes the lattice strain, the transition energies of SMQWs were calculated using the conduction-band offset (Q(c)=Delta E(c)/Delta E(g)) as an adjustable parameter. The best fit of measured and calculated interband transition energies suggests that Q, is independent of As composition and is 0.70+/-0.05. Finally, a growth kinetics model based on the Langmuir equation was derived to realize the As/P incorporation ratio in the InAsP materials. Theoretical results show good agreement with experimental data.