Ⅲ-nitride semiconductors hare attracted mach attention recently due to their applications in eletronic and optoelectronic such as high bright blue and green light emitting diodes(LEDs) and laser diodes(LDs).InGaNhas been used as active layers for most nitride LEDs.However

the luminescence mechanism in InGaN alloys is still in question

especially how the structural and compositional homogeneities in the alloy affect on the optical properties of the devices.Photoluminescence properties of InGaN film grown on sapphire substrates by metal organic chemical vapor deposition(MOCVD) were experimentally investigated by means of X-ray diffraction(XRD)

transmission spectra and PL spectrum.The peaks of InGaN

InN and In were observed on XRD spectrum. It might be evidence of phase separation and In quantum dots in the sample.Aclear oscillation could be observed on transmission spectra of the sample.As PLspectra excited by xenon lamp

a blue shift of emission peak position was observed.Additionally

when the optical excitation density was increased

the emission peak will split to three peeks.That could be explained by interference due to F-Pcavity arising from surface of sample.The excitation density dependence of PLintensity shows that these emission peaks have different character

the two high energy peak might be originated from local exciton recombination

and the low energy peak is stimulated emission peak

and might be originated from electron-hole plasma(EHP) recombination.Temperature dependence of PLspectra was investigated

peak positions of high energy peak changed with "S-shape" by increasing of temperature

and it is different from character of the low energy peak.The red shift of the peak positions as increase temperature indicated the increasing of refract index.