Effect of temperature on InGaAsP alloy composition

Abstract

The influence of growth temperature on the composition of InGaAsP films grown by low pressure metalorganic vapor phase epitaxy (MOVPE) is reported for quaternary (Q) alloys having bandgap wavelengths of λg = 1.1, 1.3, and 1.5 μn. Films with these different Q-compositions were deposited lattice matched to InP at a growth temperature of 675°C. Subsequent growth experiments were then performed for each Q-composition in which the input gas flow rates were kept the same and only the temperature changed in 25°C decrements down to 600°C. Photoluminescence (PL) and lattice mismatch (LMM) measurements of the resulting films were used to determine the effect of growth temperature on film composition. The PL data indicate a temperature shift in the PL wavelength of −1.8 nm/ °C for the 1.5Q composition, −2.9 nm/°C for 1.3Q, and −4.3 nm/°C for 1.1Q. Negative shifts were also observed in LMM of −80 ppm/°C for 1.5Q, −150 ppm/°C for 1.3Q, and −250 ppm/°C for 1.1Q. The Ga/In and P/As ratios of the Q-filmswere measured by secondary ion mass spectroscopy and correlated with full-wafer maps of the PL wavelength and lattice mismatch to gain insight into the processes responsible for wafer nonuniformity in MOVPE.