Abstract
The relationship between the performance of avalanche photodiode (APD) and structural parameters of the absorption, grading, and multiplication layers has been thoroughly simulated and discussed using the equivalent materials approach and Crosslight software. Based on separate absorption, grading, charge, and multiplication (SAGCM) structure, the absorption layer of APD was replaced with InGaAs/GaAsSb superlattice compared to conventional InGaAs/InP SAGCM APD. The results indicated that the breakdown voltage increased with the doping concentration of the absorption layer. When the thickness of the multiplication layer increased from 0.1 μm to 0.6 μm, the linear range of punchthrough voltage increased from 16 V to 48 V, and the breakdown voltage decreased at first and then increased when the multiplication layer reached the critical thickness at 0.35 μm. The grading layer could not only slow down the hole carrier, but also adjust the electric field. The dark current was reduced to about 10 nA and the gain was over 100 when the APD was cooled to 240 K. The response wavelength APD could be extended to 2.8 μm by fine tuning the superlattice parameters. The simulation results indicated that the APD using superlattice materials has potential to achieve a long wavelength response, a high gain, and a low dark current.
Highlights
In recent years, with the growing concern about eye safety in light detection and ranging (LiDAR) [1] and capacity saturation in traditional communication wavebands, the extended wavelength avalanche photodiode has attracted increasing attention
Avalanche photodiodes (APDs) are ideal for the operation in this spectrum range because its internal gain provides a higher sensitivity than conventional photodiodes, which significantly improves the sensitivity of the receiver
The HgCdTe material can provide an adjustable band gap in the range of 0–1.6 eV, making it an excellent absorption material for all infrared bands. It has a high quantum efficiency (QE) (>70%, at room temperature) in the range of 1–3-μm short-wave infrared (SWIR), but the CdZnTe substrates required for the growth of HgCdTe material are expensive [6]
Summary
With the growing concern about eye safety in light detection and ranging (LiDAR) [1] and capacity saturation in traditional communication wavebands, the extended wavelength avalanche photodiode has attracted increasing attention. Avalanche photodiodes (APDs) are ideal for the operation in this spectrum range because its internal gain provides a higher sensitivity than conventional photodiodes, which significantly improves the sensitivity of the receiver. The HgCdTe material can provide an adjustable band gap in the range of 0–1.6 eV, making it an excellent absorption material for all infrared bands. InSb is a primary material candidate for 2-μm APD applications This material exhibits very low excess noise, it must be operated at cryogenic temperatures to reduce dark current. APDs based on group III-V. such as AlInAsSb and InGaAs/GaAsSb superlattice materials, have become a hot spot for domestic and international research due to their excellent performance and suitable detection wavelength range. We use Crosslight software to simulate the layer structure of T2SL extended wavelength APD and research the relationship between each layer of the APD. The layer structure design of In0.53 Ga0.47 As/GaAs0.51 Sb0.49 T2SL extended wavelength APD was discussed
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