Photodiodes or photo-detectors are the pin semiconductor devices capable of converting light energy into electric current. Avalanche Photodiode or APD are highly sensitive photodetectors with internal gain mechanism and fast rise time and operated at high reverse voltage. APDs are recommended for very sensitive detectors, applications which require high bandwidth/high modulation frequency, less electronic signal amplification or low optical signal strength, and low electronic noise. APDs are suitable for Long Range applications in high ambient light and where direct TOF has to be calculated. Also, the high dynamic range of APDs allow its usage for applications such as object detection, optical distance measurement, remote sensing, scanning, and object/shape recognition Laser meter, laser range finder, area scanning, and LiDAR systems are some of the major applications of APDs and can be served in industries such as military, medical, industrial and automotive.
Amongst these industries automotive has been witnessed as the most lucrative due to the disruption caused by advent of ADAS and Self-Driving/ Autonomous Driving technology. This growth demand from autonomous driving space is going to be a game changer for APD manufacturers. LiDAR is expected to attain high peak growth by capturing larger share of autonomous driving sensor’s pie. The tremendous advancement of LiDAR in automotive space has instigated the growth of photodetector’s/ APD market in this industry. The demand of high-volume, cost-effective packaging combined with high levels of reliability from the automotive LiDAR manufacturers has put immense pressure on APD providers for innovation and advancement in the field.
Other than APDs, PIN Photodiodes, Single-Photon Avalanche Diodes (SPAD) and Silicon Photomultipliers (SiPM) are some of the other detectors that can be used as single-element or array in LiDARs depending on applications. Amongst these detectors, SiPM can only be used with silicon technology while others can be based on silicon or compound semiconductors. APDs are highly preferred for autonomous driving LiDARs due to above mentioned characteristics. From the available wavelength range of APDs- 300nm to 1700nm; silicon APDs can be operated from 300nm to 1100nm, germanium between 800nm and 1600nm, and InGaAs from 900nm to 1700nm. The silicon APDs operate in Geiger mode are relatively cheaper than other APDs, hence most of the companies are providing standard 905nm APDs for automotive LiDAR applications. InGaAs APDs are highly recommended due to its low noise and higher bandwidth and extended spectral response to 1700nm. However, this APD comes with very high cost, hence Germanium is primarily recommended for the application in high electro-magnetic interference (EMI).
Currently, most of the leading APD providers are offering 905nm as standard wavelength of autonomous driving LiDARs so as to achieve cost effective and reliable solution. Major leaders in this market such as Hamamatsu Photonics, Excelitas Technologies and First Senor are providing 905nm APDs while SemiNex Corporation and Voxtel, Inc. are working on 1550nm wavelength for automotive LiDARs.
The other major players providing reliable APDs for automotive LiDAR includes SensL, Philips, Advanced Scientific Concepts, Discovery Semiconductors Inc., Spectrolabs, Espros Photonics Corporation, Laser Components, Micro Photon Devices, Ams Technologies, Analog Modules Inc., OSI Laser Diode, Inc., Pro-Lite Technologies Ltd and among others.
Tremendous strategic developments have been witnessed between APD providers and automotive LiDAR manufacturers from past few years. For instance, Hamamatsu Photonics and Excelitas has partnered with the LiDAR manufacturer LeddarTech, Advanced scientific concepts is acquired by Continental, SensL is acquired by On Semiconductors, and First Sensor has partnered with Velodyne LiDAR.