Ultra‐High‐Speed Dilute Nitride Photodetectors on GaAs Substrate for 1310 nm Operation

Abstract Ultra‐high‐speed photonic devices covering O‐ and C‐bands (1260–1565 nm) are in great demand for datacom and telecom applications, and are almost exclusively produced on InP substrates due to its bandgap, and high carrier mobility. Addition of small amounts of Nitrogen to III–V compounds, known as dilute nitride (DN) technology, modifies the bandgap, but results in high effective masses, making it unsuitable for transit‐time dependent devices such as transistors, PIN and metal‐semiconductor‐metal photodetectors (MSM‐PD's). A family of devices is produced that circumvent these limitations by incorporating doped heterojunctions that decrease the dark current, produce reservoir(s) of confined two‐dimensional electron gas (2DEG), and landscape the electric field. Consequently, optically generated electrons navigate a thin absorption region to reach the 2DEG, causing current in external circuitry without arriving at anode. These 2DEG‐DNMSM's have low dark current (<1.0 nA), and the fastest reported DN response speed with rise time of 11 ps, fall time of 28 ps, and pulse‐width of 14 ps; a speed which remains the same even when cathode‐anode distance increases by 3x. These opto‐plasmonic InGaAs:N devices, fabricated on GaAs using standard processes compete favorably, at fraction of the cost, with InGaAs on InP devices which have > 60x higher electron mobility.