The role played by strain on phase separation in InGaN quantum wells

• The strain magnitude is decreased by introducing InGaN interlayers into GaN barriers.
• The enhanced phase separation taking place in larger strained InGaN QWs is observed.
• The strain-driven kinetic phase separation should be taken into account in our case.

Through designing the quantum well (QW) structure by introducing the InGaN interlayers into the GaN barriers, the compressive strain magnitude is significantly decreased. Two distinct emission peaks corresponding to In-rich localized state and quantum well ground state emissions observed from the electroluminescence (EL) spectra demonstrate that the phase separation is enhanced to form In-rich localized states in the original structure with larger strain, but no significant phase separation is observed in the designed structures with less strain. This abnormal phenomenon is contrary to the previous reports that phase separation in the InGaN layer can be suppressed by compressive strain. Therefore, it is suggested that the strain-driven kinetic phase separation should be taken into account in our case to more fully and precisely understand the role played by strain on phase separation that strain can hinder the phase separation thermodynamically but may drive phase separation kinetically.