Thickness modulation and strain relaxation in strain-compensated InGaP/InGaP multiple-quantum-well structure grown by metalorganic molecular beam epitaxy on GaAs (100) substrate

•Strain-compensated InGaP/InGaP MQWs were grown by MOMBE on GaAs (100) substrates.•The TEM image showed noticeable thickness modulation in the barrier layers.•Analysis of the XRD pattern revealed that large strain relaxation occurred in the well layers.•Decreasing the substrate temperature suppressed the crystalline degradation.•The sample grown at 510 °C had 50 times higher PL peak intensity than the sample grown at 530 °C.

We have investigated the structural features of a strain-compensated InGaP/InGaP multiple-quantum-well (MQW) structure on GaAs (100) substrate with a band-gap energy of around 1.7 eV for solar cell applications. In transmission electron microscopy images, noticeable thickness modulation was observed in the barrier layers for a sample grown at the substrate temperature of 530 °C. Meanwhile, the X-ray diffraction patterns indicated that strain relaxation predominantly occurred in the well layers. Decreasing the substrate temperature from 530 to 510 °C was effective in suppressing both the thickness modulation and strain relaxation. Additionally, increasing the growth rate of the well layer further suppressed the thickness modulation. In room-temperature photoluminescence (PL) emission spectra, the sample grown at 510 °C showed approximately 50 times higher PL peak intensity than the one grown at 530 °C.