The optical and electrical properties of In0.29Al0.71As/In0.3Ga0.7As/GaAs metamorphic high electron mobility transistor (MM-HEMT) structures grown by molecular beam epitaxy were investigated. The RT PL spectrum shows four peaks, corresponding to In0.29Al0.71As layer grown at 380 degrees C (peak C), In0.29Al0.71As layer grown at 520 degrees C (peak D), the e2-hhl and e1-hhl transitions (the second electron and the first subband to first hole subband) in the channel, respectively. The deviation between peak C and peak D is attributed to In desorption due to high growth temperature, strain resulted from incomplete relaxation of metamorphic InAlAs. The sheet carrier concentration (N-s) and electron mobility (mu) decrease with the deviation increasing, which indicates the electrical properties depend on the quality of metamorphic MM buffers significantly. Therefore, the electrical properties of MM-HEMT can be nondestruclively evaluated by room temperature PL spectra. (c) 2006 Published by Elsevier Ltd.