High-speed uni-traveling-carrier photodiodes on silicon nitride

Abstract

Integrated photonics is an emerging technology for many existing and future tele- and data communication applications. One platform of particular interest is Silicon Nitride (SiN) thanks to - amongst others - its very low-loss waveguides. However, it lacks active devices, such as lasers, amplifiers and photodiodes. For this, hybrid or heterogeneous integration is needed. Here, we bring high-speed uni-travelling-carrier photodiodes (UTC PDs) to a low-loss SiN-platform by means of micro-transfer-printing. This versatile technology for heterogeneous integration not only allows very dense and material-efficient III-V integration, it also eases fabrication yielding high-performance detectors. The waveguide-coupled photodiodes feature a responsivity of 0.3 A/W at 1550 nm, a dark current of 10 nA and a bandwidth of 155 GHz at a low bias. At zero bias, a record bandwidth of 135 GHz is achieved. We further demonstrate that this integrated detector can be used for direct photomixing at terahertz frequencies. A back-to-back communication link with a carrier frequency around 300 GHz is set up, and data rates up to 160 Gbit/s with low error vector magnitude (EVM) are shown, showcasing near-identical performance at zero bias.

Integrated PbS Colloidal Quantum Dot Photodiodes on Silicon Nitride Waveguides

“…Most of the photodetectors integrated on SiN waveguides reported in literature were based on bonded or transfer-printed III–V semiconductors, , Ge monolithically grown on Si, , and two-dimensional materials, , approaches that result in increased integration complexity. Integration of evaporated amorphous and polycrystalline photoconductors has also been demonstrated, offering promising pathways for less complex heterogeneous integration.…”

“…While the saturation power of WG-QDPDs is better than that of two-dimensional materials photodetectors, it is still not on par with III–V or Ge photodetectors, which have saturation powers exceeding 1 mW. , Hence, a significant enhancement of the saturation power is needed to make WG-QDPDs competitive in this way, a step that is contingent upon better fabrication techniques and the design and operation of the QDPD stack. For the fabrication, we believe that minimizing damage to the QD and transport material films, as well as ensuring cleaner interfaces, could significantly enhance the performance of WG-QDPDs, bringing them closer to that of planar QDPDs.…”

“…In addition, our WG-QDPDs demonstrate a high responsivity of 0.69 A/W at around 1.3 μm, which is comparable to, or even better than, reported waveguide-coupled PDs. 53,55,60 Moreover, the use of QDs as active material offers the benefits of a low-cost material, compatibility with standard fabrication techniques, ease of processing, and scalability toward higher volume production. These features make WG-QDPDs attractive for low-cost, lowpower, and noise-sensitive applications.…”

“…49 This demonstrates the flexibility of this on-chip approach and opens up its use in many different applications such as in vivo glucose monitoring 50,51 and fiber Bragg grating readout. 52 ■ DISCUSSION Most of the photodetectors integrated on SiN waveguides reported in literature were based on bonded or transfer-printed III−V semiconductors, 37,53 Ge monolithically grown on Si, 54,55 and two-dimensional materials, 56,57 approaches that result in increased integration complexity. Integration of evaporated amorphous 58 and polycrystalline 59 photoconductors has also been demonstrated, offering promising pathways for less complex heterogeneous integration.…”

High-speed PiN photodiode design space exploration to break the speed-efficiency trade-off

“…High-speed silicon-compatible photodiodes are in high demand due to their transcendent applications across domains in data communication, photon detection, and advanced imaging. To cater to the need for visible light and near-infrared wavelength applications (e.g., visible light communication, 1 fluorescence lifetime imaging, 2 and light detection and ranging 3 ), semiconductors such as silicon, [4][5][6][7][8] GaAs, 9 and InGaAs [10][11][12] are being explored. In addition to the type of absorber material, various device architectures such as metal-semiconductors-metal detectors, lateral illumination photodiodes, 13 PiN, 7,8 avalanche photodiodes (APD), 14,15 and single-photon detectors are proposed for high-speed communication and imaging applications.…”