InGaN/GaN multiple quantum wells light emitting diodes (LEDs) with 2 mu m thick crack-free GaN buffer layers were grown on porous Si substrates by metalorganic chemical vapor deposition. The material properties of LEDs grown on porous Si were studied in comparison with LEDs grown on grid-patterned Si. The (1 0 (1) over bar 5) asymmetric reciprocal space mapping (RSM) results indicate that LEDs grown on porous Si have less lattice tilt or distortion than those grown on grid-patterned Si. Both RSM and micro-photoluminescence (micro-PL) measurements suggest that multiple quantum wells grown on porous Si are less stressed. Mechanisms behind this partial strain relaxation are discussed. (C) 2010 Elsevier B.V. All rights reserved.