Key Takeaways & Executive Findings
- •• A low-noise SAGCM InGaAs/AlGaAsSb APD operating at 1550 nm was successfully fabricated with a double-mesa structure. • The double-mesa structure reduces the electric field at the multiplication region edge by nearly 100 kV/cm compared to single-mesa, suppressing trap-assisted tunneling and reducing dark current by up to four times. • The AlGaAsSb APD exhibits an exceptionally low excess noise factor with a k-value of approximately 0.014, outperforming traditional multiplication materials. • This work validates the potential of AlGaAsSb APDs for achieving both low dark current and low noise, promising for applications in optical communication and LIDAR.
Abstract
Avalanche photodiode (APD) is a kind of photodetector with important applications in optical communication, light detection and ranging (LIDAR) and other fields. APDs fabricated using the recently developed AlGaAsSb as the multiplication material exhibit excellent noise performance. In this work, we report a low-noise separate absorption, grading, charge, and multiplication (SAGCM) InGaAs/AlGaAsSb APD operating at 1550 nm. A double-mesa structure was fabricated to reduce the dark current. Numerical simulations were conducted to compare two different mesa-structured APDs. By analyzing the electric field distribution, it was found that the electric field at the edge of the multiplication region in the double-mesa APD is nearly 100 kV/cm lower than that of the single-mesa structure. Experimental results demonstrate that after device punch-through, the double-mesa APD’s dark current can be reduced by up to four times compared to the single-mesa APD. Quantitative analysis of the dark current components in the AlGaAsSb APD further confirms that the low sidewall electric field in the double-mesa structure effectively suppresses the trap-assisted tunneling. Additionally, noise measurements indicate a k-value of approximately 0.014, which is significantly lower than that of traditional multiplication materials. This work provides preliminary validation for further performance improvements in low noise and low dark current AlGaAsSb APDs.
1. Introduction
In recent years, avalanche photodetectors (APDs) have found increasingly widespread applications. Highly sensitive avalanche photodiodes operating at infrared wavelengths can be used in fields such as autonomous vehicle sensing, free-space optical communication, and climate change monitoring[1−3]. In scenarios involving few photons, avalanche photodiodes enhance photon detection efficiency through avalanche multiplication. This gain is often accompanied by excess noise due to the stochastic nature of the impact ionization process.
Currently, low noise antimonide materials have attracted significant attention from researchers, including AlAsSb[4], AlInAsSb[5−7], and AlGaAsSb[8−22]. The incorporation of Ga into AlAsSb has been demonstrated to effectively reduce surface leakage currents[16]. And APD with AlGaAsSb multiplication layer has lower excess noise than AlInAsSb[6−9]. The AlGaAsSb PIN structure of different thicknesses shows that it has a k value of 0.005−0.01[17−22]. In 2022, Collins et al. reported t
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Yuhang He, Rui Wang, Yan Liang, Yingqiang Xu, Guowei Wang, Haiqiao Ni, Shuo Wang, Zhichuan Niu, Xiaohong Yang (2025). Mesa-structured AlGaAsSb APD: dark current and noise analysis. SinoTechIntel Verified Research. https://doi.org/10.1088/1674-4926/25020025
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Frequently Asked Questions
What is the key innovation of this AlGaAsSb APD?
The key innovation is the use of a double-mesa structure in an InGaAs/AlGaAsSb SAGCM APD, which significantly reduces the electric field at the multiplication region edge, thereby suppressing trap-assisted tunneling and reducing dark current by up to four times compared to a single-mesa design.
How does the double-mesa structure affect the device performance?
The double-mesa structure lowers the electric field at the edge of the multiplication region by nearly 100 kV/cm, which effectively suppresses trap-assisted tunneling and reduces dark current. This leads to improved signal-to-noise ratio and overall device performance.
What is the measured excess noise factor (k-value) of the AlGaAsSb APD?
The measured k-value is approximately 0.014, which is significantly lower than that of traditional multiplication materials such as InP or Si, indicating excellent noise performance.
What are the potential applications of this APD?
This low-noise, low-dark-current APD operating at 1550 nm is suitable for applications in optical communication, LIDAR, free-space optical communication, and other photon-starved environments.
How was the dark current reduction validated?
The dark current reduction was validated through numerical simulations and experimental measurements. Simulations showed a lower electric field at the multiplication region edge in the double-mesa structure, and experiments demonstrated up to four times reduction in dark current after device punch-through.
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