Optical properties of as-grown and annealed InAs(N)/InGaAsP strained multiple quantum wells

Abstract

Optical and structural properties of as-grown and annealed InAs(N)/InGaAsP strained multiple quantum-well (MQW) structures grown by gas source molecular-beam epitaxy are investigated by photoluminescence (PL), double crystal x-ray diffraction, and photoconductivity spectroscopies. Properties of the as-grown and annealed MQW’s are studied and those of the InAs/InGaAsP MQW (C821) and the InAsN/InGaAsP MQW with the lowest nitrogen contents N=1.1% in the well (C822) are compared. For the C821 InAs/InGaAsP MQW with a very large total strain, a low energy shoulder, possibly induced by defects or impurities, can be seen in the low temperature PL spectrum, and a large density of nonradiative recombination centers is found. For nitrogen-containing MQW’s, the PL full width at half maximum and PL peak evolutions with increasing annealing temperature are influenced by the alloy inhomogeneities. The initial redshift of the PL peak after rapid thermal annealing means that the luminescence is dominated by As-rich regions in these as-grown samples. Exciton localization induced by alloy disorders is also found in high-nitrogen-content samples. By comparing the experimental results of C821 and C822, adding a little nitrogen to reduce the rather large total strain in the structure is beneficial to structural and optical quality improvement.