Influence of the barrier composition in GaN/InxAl1−xN quantum wells properties

• We have grown GaN/InAlN multiple quantum wells (5 periods) on GaN on sapphire.
• The In composition in the barrier was changed by varying growth temperature from 7% to 18%.
• The well thicknesses varied from 1 nm to 2 nm.
• When the In composition decreases, the photoluminescence spectra show a blue-shift for the 1 nm-thick well samples and a red-shift for the 2 nm-thick well samples.
• Competition between confinement effect and electric field effect.

GaN/InxAl1−xN quantum wells with varying In composition in the InxAl1−xN barrier and varying GaN well thickness were grown by metal–organic vapor phase epitaxy on a c-plane sapphire. The as-grown samples were characterized by high resolution X-ray diffraction to determinate the composition and the relaxation state. The surface was observed by atomic force microscopy and the photoluminescence was measured at low temperature. A competition between the confinement effect and electric field effect has been evidenced. Under a critical well thickness, the luminescence is blue-shifted with the decrease of the In composition while above this critical thickness, the opposite behavior is observed.