Bandgap tuning of In _0.53 Ga _0.47 As/InPmultiquantum well structureby impurity free vacancy diffusionusing In _0.53 Ga _0.47 As cap layer and SiO ₂ dielectric capping

Integration of waveguide-type wavelength demultiplexing photodetectors by selective intermixing of InGaAs/InGaAsP quantum well structure

“…In this case, absorption loss and photocurrent generation for 1561 nm is small in the area annealed with the SiO dielectric cap and low crosstalk is expected in this wavelength. In order to achieve a large bandgap difference, an MQW with a large bandgap difference, such as InGaAs(P)-InP or InGaAs-InAlAs, is preferable because under the same annealing condition, a larger bandgap shift can be obtained compared with lattice matched InGaAs-InGaAsP MQW structure [7]- [9]. This is because confined electron, heavy and light hole energies in the MQW will be affected to a greater extent and bandgap shifts for a fully intermixed MQW will be larger for thinner wells and larger bandgap difference between well and barrier materials.…”

“…The intermixing techniques for InP-based MQW's are important because of their potential application in 1.55 m fiber-optic communication systems in optoelectronic devices which require different bandgap energies. We recently reported on an impurity free vacancy diffusion (IFVD) technique using an SiO dielectric film on an InGaAs cap layer for promoting the intermixing of an InGaAs-InP MQW system, in which large bandgap shifts were observed [7]. This method was also applied to InGaAsP-InP and InGaAs-InGaAsP MQW systems where the spatial resolution of the IFVD process was found to be less than 3 m and a large loss reduction in ridge-type waveguides was investigated [8], [9].…”

Disordering of Quantum Structures for Optoelectronic Device Integration

“…The diffusion of defects is mainly affected by the thermal stress imposed on the semiconductor by the capping layer during annealing due to their mismatched thermal expansion coefficients (Fu et al, 2003(Fu et al, , 2002bPepin et al, 1997), as well as the diffusion mechanism, which is largely dependent on the types of stress (compressive or tensile) and the type and concentration of point defects (vacancies or interstitials) that are generated in the heterostructures during annealing. Nevertheless, SiO 2 is still found to be able to introduce large band-gap shifts in various InP-based QW systems (Lee et al, 1997;Si et al, 1998;Yeo et al, 2000). By choosing proper dielectric layers to control both the defect generation and the diffusion processes, intermixing can be either enhanced or suppressed in different material systems, making it possible to achieve spatially selective intermixing.…”

Fast Tuneable InGaAsP DBR Laser Using Quantum-Confined Stark-Effect-Induced Refractive Index Change

“…Varying the material of the top buffer layer provides yet another parameter for bandgap detuning control, because the types of defects generated in the material during implantation depend on the material composition itself. Increased bandgap blue shifts have been reported using an InGaAs cap layer, compared to an InP cap, below the SiO 2 layer in IFVD [27], [28]. In order to investigate this in the case of shallow implantation and to select the final conditions for the QCSE-tuned lasers, we performed calibration runs using only the InP or both the InGaAs and InP implantation buffer layers of the structure of Fig.…”

“…8(a) shows in more detail the bandgap detuning for samples with an InP or InGaAs cap as a function of annealing time. There have been a number of theories on how intermixing takes place in InGaAsP, and bandgap detuning has been ascribed to the interdiffusion of both group III and group V defects [27], [28], [33]. Fig.…”