Monolithic On-chip Integration of Electronics & Photonics Using III-nitrides for Telecoms

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Internet and telecoms are facing an explosive growth in data traffic, increasing at 50% per year. This requires the development of monolithic on-chip integration of electronics and photonics, which offers a massive reduction in both footprint and processing costs. Such a compact system will require a high power density and excellent high temperature tolerance. Monolithically integrating III-nitride based electronics and photonics on silicon on a single chip will represent the most promising approach to meeting the requirements in the telecoms regime. The photonic parts include active (laser diodes) and passive (photodetectors) components linked by waveguides, where the laser diodes are controlled by high electron mobility transistors. The electronic and photonic parts both need to meet the requirements for high power, high frequency and high temperature operation, as well as excellent temperature stability and robust mechanical properties. Conventional III-V semiconductors (GaAs or InP) suffer a number of fundamental limitations such as intolerance to high-temperatures, temperature sensitivity, limited power density capacity and fragility. They also exhibit high losses due to scattering (high refractive index) and multiphoton absorption. III-nitride semiconductors all have direct bandgaps and cover a vast spectral region from deep ultraviolet to infrared. Compared with conventional III-V materials, the III-nitrides exhibit major advantages in the fabrication of high power, high frequency and high temperature devices due to their intrinsically high breakdown voltage, high saturation electron velocity and excellent mechanical hardness. III-nitrides exhibit low free carrier absorption, negligible multiphoton absorption, low refractive index (2.3 for GaN compared with 3.5 for GaAs) and superior temperature stability of the refractive index (one order of magnitude higher than that of InP). Therefore, III-nitrides offer great potential to revolutionise current internet and telecoms and enable ultra-fast speed and ultra-broad bandwidths, going far beyond that so-far achieved in the telecoms regime (1.3-1.55 um). Up to now research on III-nitrides has mainly been confined to the visible spectral range but this is not a limit. III-nitrides based devices exhibit superior properties in terms of delivering the power/efficiency required for next-generation telecoms. This is important to the communications industry, which is expected to use 20% of the global electricity by 2025, where a large proportion (>30%) is consumed by the data centre cooling systems. Monolithically integrating III-nitride electronics and photonics on silicon on a single chip by direct epitaxy in the telecoms regime would therefore offer transformative performance.Our ambitious vision is to employ the two major leading epitaxial growth techniques (MOVPE and MBE) for III-nitrides, combining the leading-expertise established at Sheffield, Cardiff and Strathclyde along with a world-leading research team at Michigan in USA in order to demonstrate the first monolithic on-chip integration of III-nitride based electronics and photonics on silicon with operation in the telecoms regime. This is expected to revolutionise current internet and telecoms.