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

A comprehensive x-ray analysis including Theta-2 Theta scans, reciprocal sp ace mapping, and x-ray reflectivity of 10x(InGaN/GaN) multiple quantum well s (MQWs) is presented. The layers were grown by low-pressure metal-organic chemical-vapor deposition. The strain state and the In concentration in (In GaN/GaN) MQW systems are evaluated with the help of reciprocal space maps a round the symmetric (0002) and asymmetric (10 (1) over bar 5) Bragg reflect ions. Depending on the In incorporation, the MQW system is fully strained, partially relaxed, or exhibits phase decomposition effects. The room-temper ature photoluminescence emission energy of a fully strained 10x(In0.125Ga0. 875N/GaN) MQW sample is 2.792 eV, which is 133 meV less than the calculated energy gap of 2.925 eV. (C) 1999 American Institute of Physics. [S0003-695 1(99)03431-2].