Evaluation of strain and In content in (InGaN/GaN) multiquantum wells by x-ray analysis

Abstract

A comprehensive x-ray analysis including Θ–2Θ scans, reciprocal space mapping, and x-ray reflectivity of 10×(InGaN/GaN) multiple quantum wells (MQWs) is presented. The layers were grown by low-pressure metal–organic chemical-vapor deposition. The strain state and the In concentration in (InGaN/GaN) MQW systems are evaluated with the help of reciprocal space maps around the symmetric (0002) and asymmetric (101̄5) Bragg reflections. Depending on the In incorporation, the MQW system is fully strained, partially relaxed, or exhibits phase decomposition effects. The room-temperature photoluminescence emission energy of a fully strained 10×(In0.125Ga0.875N/GaN) MQW sample is 2.792 eV, which is 133 meV less than the calculated energy gap of 2.925 eV.