In this work , impurity free vacancy diffusion (IFVD) quantum well intermixing(QWI) technology by high thermal-expansion-induced stress is used to perform bandgap engineering. In this paper, 1530nm InGaAsP multiple QWs sandwiched by p-InP (2£gm thickeneess, top) and n-InP (bottom) material is used as testing material structure also laser fabrication material, where contact materials (InGaAs and InP) on p-InP are used for comparison. By the difference between thermal expansion coefficients of SiO2 on the different material (InGaAs, InP), large different behaviors of QWI are observed, while low different dependence on defects created by ion-implantation is found. Above 70nm photo luminance (PL) wavelength shift of InGaAsP MQW below 2£gm thick InP is realized in this method. Further more, CW in-plane laser structures are also successfully fabricated and demonstrated by such QWI, giving the same shift as PL. It shows that good qualify of material can be obtained in such QWI method. Using local deposition of SiO2 causes different bandgap materials, re-growth free processing for monolithic integration can be expected, offering a powerful scheme of QWI for bandgap engineering.

In this work, a quantum well intermixing(QWI) technology, called impurity free vacancy diffusion(IFVD), is used to do the bandgap engineering in an optoelectronic monolithic integration. The monolithic integration of SOAs and EAMs is taken as an example. By IFVD, the transition energy levels of EAM quantum wells can be shifted to shorter wavelength region, while SOA quantum wells are kept the same. Therefore, the overall SOA-integrated EAM efficiency can be improved. We use dielectric film¡XSiO2 and Si3N4 to control the impurity free vacancy diffusion, both of these two dielectric layer will induce stress on the wafer, but they will come to the totally different result base on the difference atom chemistry with the substrate. Using Ga atom diffusion into SiO2 to relax stress, the IFVD will be operated to enhance quantum well intermixing, leading to energy bang transition change. On the other hand, with Si3N4 film, no significant intermixing is observed, implying atom chemistry dominates the whole process. Also, a super critical fluid technique by H2O2 is also employed to further improving SiO2 quality, a as large as 180nm blue shift is obtained, further improving such mechanism. Through difference properties between SiO2 and Si3N4 dielectric layers, different bandgap transitions in one single chip can be controlled in an area of 30£gm¡Ñ50£gm, leading to a planar bandgap engineering. Use these techniques, an EAM-SOA integration is designed and fabricated, obtaining an wavelength offset of 40nm with good quality of material structure. In the future, we can use this technique on large scale chip, tuning the bandgap to make photonic integration circuit without re-growth.