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

Using the selective intermixing of an InGaAs-InGaAsP multiquantum-well (MQW) structure, a wavelength demultiplexing photodetector which can demultiplex two widely separated wavelengths was fabricated. An InGaAs-InGaAsP MQW with a u-InP cladding layer and a n-InGaAs cap layer, grown by metal organic chemical vapor deposition was used. Selective area intermixing of the InGaAs-InGaAsP MQW structure was done by a rapid thermal annealing after the deposition and patterning of the SiO₂ dielectric layer on the InGaAs cap layer. The integrated structure consists of shorter and longer wavelength sections, separated by an absorber section. Shorter wavelength and absorber sections were intermixed with the SiO₂ dielectric layer. At a wavelength of 1477 nm, the output photocurrent ratio was enhanced as the length of the absorber region increased and a ratio of over 30 dB was observed, while at a wavelength of 1561 nm, an output photocurrent ratio of 18.9 dB was observed