The band gap tuning of multiple quantum wells (MQWs) structure in the compound semiconductor is becoming an important tool in fabricating optoelectronic devices.Especially

phonic integrated devices based on InGaAsP multiple quantum wells structure are particular imporance because of its dramatic increase in demand for long wavelength optical communication.To integrate several optoelectronic devices on a single wafer

we must divide area with different optolectronic properties such as refractive index and absorption wavelength.Selective regrowth and selective area epitaxy are two possible techniques that can be used for this purpose.However

there is considerable interesting in post growth quantum well intermixing (QWI) technique which can be used to modify the geometry and composition of MQWs in selected regions. There are several quantum well intermixing (QWI) techniques that provide the localized formation of band gap shifted area.Among these QWI techniques

impurity free vacancy disordering (IFVD)is believed to be a promising technique without free carrier absorption and damage of crystal lattice. In this paper

band gap blue shift of InGaAsP/InP multiple quantum wells by IFVD was investigated using photoluminescence(PL) and photoreflectance(PR).Si

3

N

4

and SiO

2

were used for the dielectric layer to create the vacancies.Then all samples were annealed by rapid thermal ananealing (RTA).The results indicate that band gap blue shift depends on the annealing temperature and time.Band gap blue shift increases with the annealing temperature and time but it tends to saturate when the annealing time attains certain extent.The SiO

2

capping was successfully used with InGaAs cladding layer to cause larger band tuning effect in the InGaAsP/InP MQWs material than Si

3

N

4

used with InGaAs cladding layer.On the other hand

samples with Si

3

N

4

-InP cap layer combinations also show larger energy shifts than SiO

2

-InP cap layer combinations.At the same time

the results of band gap blue shift measured by PR are basically consistent with the results from PL.So

photoreflectance(PR) is alternative method

which can be used to measure band gap blue shift.To our knowledge

no report was concerned with measuring band gap blue shift using PR.Furthermore

the band gap blue shift affected by cap layer combinations created a new method for IFVD investigation. Sum up

this paper first reports the results of band gap blue shift measured by PR.To obtain large energy shift

the optimal selected cap layer combination is Si

3

N

4

-InP or SiO

2

-InGaAs.