REAM-SOA integrating Ru doped InP current blocking layer

The new generation of equipments requires more and more high bit-rate transmissions. This constant augmentation of the data circulation implies an evolution towards the Fiber To the Home (FTTH) access network. The wavelength division multiplexed passive optical networks appears to be a promising candidate for the future thanks to the flexibility and the capacity. The electroabsorption modulator monolithically integrated with semiconductor optical amplifier (REAM-SOA) is very interesting for this approach being able to handle data rates of 10 Gb/s and higher [1-2]. Our REAM-SOA uses the semi-insulating buried heterostructure (SIBH) technology. Fe is a common dopant used to obtain a semi-insulating InP. A high resistivity, superior than 108 .cm can be reached, leading to reduced capacitance [3]. However, a major drawback of Fe doping is the strong interdiffusion between Fe and p-dopant located adjacent to each other in SIBH devices. This usually requires interdiffusion blocking layers made of n-doped or non-InP alloy materials [4] leading to complex technology and/or parasitic capacitance penalties. Since few years, Ruthenium has appeared to be an alternative dopant to get semi-insulating InP [5-6]. This Ru doping shows no interdiffusion with pdopant [5-6] and high resistivity characteristics. We report on the realization of an REAM-SOA using the Ru dopant (fig. 1). The active material is based on tensile-strained AlGaInAs multiple Quantum Well (MQW). A gap-wavelength detuning of 75 nm between the modulator and the SOA is realized by Selective Area Growth (SAG).