Methods of photoluminescence(PL) photovoltage(PV)

and time-resolved spectrum(TRS) are applied to study InGaAs/GaAs strained quantum well. We discover single-quantum well(SQW) and multi-quantum well(MQW) have different spectral properties; and spectral intensity of MQW is much higher and spectral full width at half maximum (FWHM) is larger than those of SQW

but spectral FWHM of SQW increases more quickly than that of MQW

which is caused by exciton-LO phonon coupling. The peaking energy of 11H obtained from PV spectrum has a little redshift compared with that from PL spectrum

which is called Stokes shift. TRS at different temperature shows luminescence delay of all three samples accords with one order at low temperature. But when the temperature is up to 70K

luminescence delay of Sample A accords with two orders

while luminescence delay of Sample B and Sample C still accord with one order. Luminescence delay with one order means one process of luminescence delay and luminescence delay with two orders means two processes of luminescence delay. Considering the different width of the three samples

we know that there are more than one sublevels in conduction or valence band of Sample A. But for the narrower width of quantum well

Sample B and Sample C have only one sublevel in conduction or valence band. As the temperature rises to 70K

KT approximates the transition energy from the first sublevel to the second one in valence

which suggests that transition may occur among valence interbands of Sample A and this transition causes luminescence delay of Sample A according with two orders when the temperature is up to 70K. We also observe that PL lifetime of MQW is longer than that of SQW

which is due to quantum tunneling effect in MQW at low temperature. The transition peaks of PV spectra and PL spectra have been identified compared with the theoretical calculation by Kronig-Penney model.