Structural and optical characteristics of In_xGa_1-xN/GaN multiple quantum wells with different In compositions

We have studied the structural and optical properties of In_xGa_1-xN/GaN multiple quantum wells with different In compositions of 8.8%, 12.0%, and 13.3% by means of high-resolution x-ray diffraction (HRXRD), photoluminescence (PL), PL excitation (PLE), stimulated emission (SE), and time-resolved PL spectroscopy. As the In composition increases, the superlattice peaks in HRXRD measurements and the PLE band edge broaden, indicating the deterioration of interface quality due to the difficulty of uniform In incorporation into the GaN layer. However, the lower room-temperature SE threshold densities of the higher In concentration samples indicate that the effect of In suppressing nonradiative recombination overcomes the drawbacks associated with increasing interface imperfection. © 1999 American Institute of Physics.