Impurity-free vacancy disordering (IFVD) using SiO 2 and SrF 2 dielectric caps to induce selective quantum-well (QW) intermixing in the GaAs-AlGaAs system is studied. The intermixing rate of IFVD was found to be higher in n-i-p and intrinsic than in p-in structures, which suggests that the diffusion of the Group III vacancy is not supported in p-type material. Single-mode waveguides have been fabricated from both as-grown and bandgap-tuned double-quantum-well (DQW) laser samples. Propagation losses as low as 8.5 dB1cm 01 were measured from the bandgap-tuned waveguides at the lasing wavelength of the undisordered material, i.e., 860 nm. Simulation was also carried out to study the contribution of free-carrier absorption from the cladding layers, and the leakage loss induced by the heavily p-doped GaAs contact layer. It was found that the leakage loss contributed by the GaAs cap layer is significant and increases with wavelength. Based on IFVD, we also demonstrate the fabrication of multiple-wavelength lasers and multichannel wavelength division multiplexers using the one-step "selective intermixing in selected area" technique. This technique enables one to control the degree of intermixing across a wafer. Lasers with bandgaps tuned to five different positions have been fabricated on a single chip. These lasers showed only small changes in transparency current, internal quantum efficiency, or internal propagation loss, which indicates that the quality of the material remains high after being intermixed. Four-channel wavelength demultiplexers based on a waveguide photodetector design have also been fabricated. Photocurrent and spontaneous emission spectra from individual diodes showed that the absorption edge was shifted by different degrees due to the selective degree of QW intermixing. The results obtained also imply that the technique can be used in the fabrication of broad-wavelength emission superluminenscent diodes.

No abstract

Large blueshift in InGaAs/InGaAsP laser structure using inductively coupled argon plasma-enhanced quantum well intermixing Suppression of interdiffusion in GaAs/AlGaAs quantum-well structure capped with dielectric films by deposition of gallium oxide J. Appl. Phys. 92, 3579 (2002); 10.1063/1.1503857 Impurity-free intermixing of GaAs/AlGaAs quantum wells using SiO x capping: Effect of nitrous oxide flow rate A phosphorus-doped silica ͑SiO 2 :P͒ cap containing 5 wt% P has been demonstrated to inhibit the bandgap shifts of p-i-n and n-i-p GaAs/AlGaAs quantum well laser structures after rapid thermal processing. The intermixing suppression has been attributed to the fact that SiO 2 :P is more dense and void free compared with standard SiO 2 together with a strain relaxation effect of the cap layer during annealing. Band gap shift differences as large as 100 meV have been observed from samples capped with SiO 2 and with SiO 2 :P. The n-i-p structure showed a higher degree of intermixing compared to p-i-n structure. This behaviour has been attributed to the rise of Fermi level in the n doped structure, through which the formation energy of Ga vacancies is reduced compared to the p doped structure.

No abstract

No abstract