Quantum well intermixing using single layer ZrO2 capped annealing on InGaAsP/InP MQW has been used to achieve integrated two wavelength photodiode pair. The selective solubility of In and Ga in ZrO2 has been used for bandgap engineering. The top layers of the hetrostructure is chosen by lithography and etching into the same hetrostructure. The regions with lower desired bandgaps are chosen to be of lower Ga content. Comparison of different top layer and anneal conditions with respect to wavelength shift and surface quality is also shown. A uniform F ion implantation performed before the annealing has shown an increase of differential blue shift. Regions with up to a minimum of 60 nm InGaAs top layer have been shown to produce a differential bandgap change of 10 nm with no F ion implantation, and 30 nm with uniform F ion implantation (when annealed at 750 °C for 10 s with 300 nm ZrO2 cap).
Viswas Sadasivan, Dagar, S., and Bhowmick, T., “InGaAsP/InP integrated waveguide photodetector pair using quantum well intermixing”, Optical and Quantum Electronics, vol. 48, 2016.