Temperature drift characteristics of Avalanche Photodetector
Avalanche photodiodes (APD Photodetector) occupy a core position in weak optical signal detection fields such as laser ranging, lidar, optical time domain reflectometry, and quantum communication due to their high gain and sensitivity. However, the performance of APD Photodetector, especially its avalanche gain (M) and breakdown voltage (Vbr), is highly susceptible to changes in ambient temperature. This temperature drift characteristic will seriously affect the stability and measurement accuracy of the system. This article analyzes the physical mechanism of Avalanche photodiodes temperature drift, summarizes the laws of its key parameters changing with temperature, and systematically introduces commonly used compensation methods such as temperature compensation circuits, bias adaptive adjustment, and temperature control.
1. The physical mechanism of temperature drift in Avalanche Photodetector
The temperature characteristics of APD Photodetector are mainly determined by the scattering mechanism of charge carriers within the semiconductor material. When a high reverse bias is applied, charge carriers are accelerated by the electric field to obtain kinetic energy, and collide and ionize with lattice atoms, generating new electron hole pairs and forming avalanche multiplication. As the temperature increases, lattice vibrations (phonon scattering) intensify, and the average free path of charge carriers between two collisions shortens. This means that carriers are more difficult to accumulate enough energy to trigger ionization, resulting in a decrease in ionization coefficients (α and β).
2. Introduction to Temperature Characteristics of Avalanche Photodetector
APD utilizes internal avalanche multiplication effect to achieve high sensitivity, but its gain is extremely sensitive to temperature. As the temperature increases, lattice vibrations (phonon scattering) intensify, the average free path of charge carriers shortens, making it more difficult to accumulate enough energy to trigger collisional ionization, resulting in a decrease in ionization coefficient. Therefore, the breakdown voltage Vbr increases with increasing temperature (positive temperature coefficient), while the avalanche gain M decreases with increasing temperature (negative temperature coefficient).
3. Compensation method
The core idea of compensation is “stable gain”, which means keeping the ratio of Vbias/Vbr (T) constant. There are three main types of engineering solutions:
3.1 Analog/digital compensation based on high-voltage bias power supply
Analog compensation: Introducing a thermistor network in the feedback/reference loop to directly output a bias voltage with a positive temperature coefficient.
MCU lookup compensation (mainstream solution): The temperature sensor monitors the temperature, and the MCU calculates the required bias voltage based on the pre stored “temperature breakdown voltage” comparison table, and controls the output of the high-voltage module through DAC. Polynomial fitting can also be used instead of table lookup to achieve bias control.
3.2 Integration of Temperature Sensor and BOOST Boost Circuit Closed Loop Control
3.3 Semiconductor Refrigerator (TEC) PID Constant Temperature Control
4. Summary and selection suggestions
The temperature drift of Avalanche Photodetector is due to the dependence of semiconductor ionization rate on lattice scattering, manifested as Vbr positive temperature coefficient and M negative temperature coefficient.
The compensation method should be selected based on a balance between cost, performance requirements, and environmental constraints
Low cost scenario → Thermistor simulation compensation
Universal high-precision scenario → MCU digital voltage regulation (lookup/fitting)
Extreme sensitivity scenario → TEC constant temperature control
With the development of LiDAR and quantum communication, high-precision and miniaturized intelligent temperature compensation schemes will become a key support for the application of APD photodetector.
Post time: Aug-26-2026