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The silicon nitride/silicon (Si₃N₄/Si) photonic platform has attracted significant interest due to its ultra-low-loss waveguides and high-performance optical components. Progress in heterogeneous integration has enabled the development of active photonic devices on Si₃N₄, including PIN waveguide photodiodes. However, to the best of our knowledge, an integrated avalanche photodiode (APD) with internal gain operating at 1550 nm wavelength has not been demonstrated to date. Here, we report on the design, fabrication, and characterization of InP/InGaAs separate absorption, charge, and multiplication (SACM) APDs heterogeneously integrated on Si₃N₄waveguides. Our APDs have a dark current of 5 nA near breakdown at room temperature, a multiplication gain of 166, and an internal responsivity of 0.61 A/W at unity gain. The 3-dB bandwidth is 4.2 GHz, and we demonstrate open eye diagrams at 7.5 Gbps. 

Matrix-based quantum kinetic simulations have been widely used for the predictive modeling of electronic devices. Inelastic scattering from phonons and electrons are typically treated as higher-order processes in these treatments, captured using mean-field approximations. Carrier multiplication in avalanche photo-diodes (APDs), however, relies entirely on strongly inelastic impact ionization, making electron-electron scattering the dominant term requiring a rigorous, microscopic treatment. We go well beyond the conventional Born approximation for scattering to develop a matrix-based quantum kinetic theory for impact ionization, involving products of multiple Green’s functions. Using a model semiconductor in a reverse-biased p-i-n configuration, we show how its calculated nonequilibrium charge distributions show multiplication at dead-space values consistent with energy-momentum conservation. Our matrix approach can be readily generalized to more sophisticated atomistic Hamiltonians, setting the stage for a fully predictive, first-principles theory of APDs. 

This paper presents a physics-based approach to calculate the alloy scattering rate in Sb-based quaternary alloys. Considering the screened Coulomb interactions and electronic band non-parabolicity in III-V semiconductors, our method advances Monte Carlo simulations, enabling precise modeling and improved design of APDs for enhanced performance. 

Highly mismatched B-III–V alloys present a promising avenue for near-infrared (NIR), direct bandgap optoelectronics that can be integrated on GaAs or Si, owing to their ability to vary bandgap and lattice constant independently. Here, we report the epitaxial growth, fabrication, and characterization of nearly strain-free, all-BGaInAs, p-i-n photodiodes on GaAs substrates grown by molecular beam epitaxy. Incorporating boron effectively reduced the strain in InGaAs, yielding nearly lattice-matched BGaInAs layers with high surface quality, as confirmed by high-resolution x-ray diffraction and atomic force microscopy measurements. Strong photoluminescence (PL) intensity was observed for BGaInAs with up to 3.2% B (7% In). The operating wavelength consistently extended with increasing boron and indium incorporation as evidenced by PL and external quantum efficiency measurements, which agree with density functional theory predictions. Altogether, these results highlight precise control of the operating wavelength and suggest highly substitutional boron incorporation. BGaInAs photodiodes with low boron and indium concentrations demonstrated high sensitivity with low dark current. We also report the effective thermal conductivity of the BGaInAs p-i-n structures and find that the thermal conductivity is largely insensitive to boron content with dominant effects from the indium content. Altogether, these findings underscore the potential for strain-free BGaInAs photodiodes as promising candidates for high-performance NIR optoelectronics. 

The proposed Monte Carlo model reveals the effect of alloy scattering on the excess noise factor (F(M)) in Al_0.7InAsSb avalanche photodiodes. A comparison between the F(M) of different combinations of scattering rates is investigated. 

Al_xIn_1−xAs_ySb_1−yis a promising multiplier for avalanche photodiodes (APD) on InP for near-infrared applications. In this work, we investigated the potential of two different ternary-containing layer stacks for the growth of AlInAsSb digital alloys on InP and InP-on-Si templates with applications in future photodetectors. STEM measurements confirmed high-quality material and interfaces on both substrates with no evidence of phase separation. Low dark currents and high gains were measured from PIN diodes grown on both substrates, with slightly higher dark currents observed in the Si-based device due to defects resulting from lattice mismatch in the template. 

Single-photon avalanche diodes (SPADs) that are sensitive to photons in the Short-wave infrared and extended short-wave infrared (SWIR and eSWIR) spectra are important components for communication, ranging, and low-light level imaging. The high gain, low excess noise factor, and widely tunable bandgap of Al_xIn_1-xAs_ySb_1-yavalanche photodiodes (APDs) make them a suitable candidate for these applications. In this work, we report single-photon-counting results for a separate absorption, charge, and multiplication (SACM) Geiger-mode SPAD within a gated-quenching circuit. The single-photon avalanche probabilities surpass 80% at 80 K, corresponding with single-photon detection efficiencies of 33% and 12% at 1.55 µm and 2 µm, respectively.