Recent advances in high sensitivity avalanche photodetectors

Recent advances in high sensitivity avalanche photodetectors

Room temperature high sensitivity 1550 nm avalanche photodiode detector

In the near infrared (SWIR) band, high sensitivity high speed avalanche diodes are widely used in optoelectronic communication and liDAR applications. However, the current near-infrared avalanche photodiode (APD) dominated by Indium gallium arsenic avalanche breakdown diode (InGaAs APD) has always been limited by the random collision ionization noise of traditional multiplier region materials, indium phosphide (InP) and indium aluminum arsenic (InAlAs), resulting in a significant reduction in the sensitivity of the device. Over the years, many researchers are actively looking for new semiconductor materials that are compatible with InGaAs and InP optoelectronic platform processes and have ultra-low impact ionization noise performance similar to bulk silicon materials.

The innovative 1550 nm avalanche photodiode detector helps the development of LiDAR systems

A team of researchers in the United Kingdom and the United States have for the first time successfully developed a new ultra-high sensitivity 1550 nm APD photodetector (avalanche photodetector), a breakthrough that promises to greatly improve the performance of LiDAR systems and other optoelectronic applications.

New materials offer key advantages

The highlight of this research is the innovative use of materials. The researchers chose GaAsSb as the absorption layer and AlGaAsSb as the multiplier layer. This design differs from traditional InGaAs/InP and brings significant advantages:

1.GaAsSb absorption layer: GaAsSb has a similar absorption coefficient to InGaAs, and the transition from GaAsSb absorption layer to AlGaAsSb (multiplier layer) is easier, reducing the trap effect and improving the speed and absorption efficiency of the device.

2.AlGaAsSb multiplier layer: AlGaAsSb multiplier layer is superior to traditional InP and InAlAs multiplier layer in performance. It is mainly reflected in high gain at room temperature, high bandwidth and ultra-low excess noise.

With excellent performance indicators

The new APD photodetector (avalanche photodiode detector) also offers significant improvements in performance metrics:

1. Ultra-high gain: The ultra-high gain of 278 was achieved at room temperature, and recently Dr. Jin Xiao improved the structure optimization and process, and the maximum gain was increased to M=1212.

2. Very low noise: shows very low excess noise (F < 3, gain M = 70; F<4, gain M=100).

3. High quantum efficiency: under the maximum gain, the quantum efficiency is as high as 5935.3%. Strong temperature stability: breakdown sensitivity at low temperature is about 11.83 mV/K.

Fig 1 Excess noise of APD photodetector devices compared with other APD photodetector

Wide application prospects

This new APD has important implications for liDAR systems and photon applications:

1. Improved signal-to-noise ratio: The high gain and low noise characteristics significantly improve the signal-to-noise ratio, which is critical for applications in photon-poor environments, such as greenhouse gas monitoring.

2. Strong compatibility: The new APD photodetector (avalanche photodetector) is designed to be compatible with current indium phosphide (InP) optoelectronics platforms, ensuring seamless integration with existing commercial communication systems.

3. High operational efficiency: It can operate efficiently at room temperature without complex cooling mechanisms, simplifying deployment in various practical applications.

The development of this new 1550 nm SACM APD photodetector (avalanche photodetector) represents a major breakthrough in the field, Addresses key limitations associated with excess noise and gain bandwidth products in traditional APD photodetector (avalanche photodetector) designs. This innovation is expected to boost the capabilities of liDAR systems, especially in unmanned liDAR systems, as well as free-space communications.