Dynamic Photodiode Array Bias Switching for Single-Photon Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current photodetectors, such as Dynamic Photodiodes (DPDs) and Single-Photon Avalanche Diodes (SPADs), face limitations in sensitivity and operational efficiency, particularly in detecting single photons and adapting to varying light conditions.
Innovation Solution
A refined DPD design that allows single-photon detection by configuring the device to generate photocurrent from a single electron-hole pair, enabling lower operational voltage and tunable sensitivity, which can be adjusted for single or multiple photon detection, and reducing pixel area for improved background light immunity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional pn or pin photodetector is operated at constant reverse bias voltage, then the photocurrent magnitude is proportional to light intensity, but the sensitivity is insufficient for single-photon detection
Solution Approach 1:
The patent applies dynamic bias voltage switching, alternating between reverse bias (for photon detection) and forward bias (for signal readout). This dynamic operation enables the photodetector to achieve both high sensitivity for single-photon detection and reliable signal extraction, resolving the contradiction between measurement precision and reliability.
Solution Approach 2:
The patent changes the bias voltage parameter dynamically between reverse and forward bias states. By modulating this parameter, the photodetector can operate in different modes: reverse bias for accumulating charge from single photons (improving sensitivity) and forward bias for reading out the signal (ensuring reliability).
2Measurement precision
If an avalanche photodiode (APD) is operated under high reverse bias voltage to achieve single-photon sensitivity, then single-photon detection becomes possible, but the operational voltage becomes excessively high
Solution Approach 1:
The patent employs periodic switching between reverse bias and forward bias modes. During the reverse bias phase, the detector accumulates charge from photons; during the forward bias phase, the accumulated charge is read out. This periodic action allows single-photon sensitivity to be achieved without maintaining continuously high voltage, thereby reducing overall energy consumption.
Solution Approach 2:
By dynamically switching the bias voltage between two states rather than maintaining a constant high voltage, the patent achieves single-photon detection sensitivity only when needed (during reverse bias), while reducing energy consumption during the readout phase (forward bias).
3Object-affected harmful factors
If the DPD pixel area is reduced to improve background light immunity, then background noise is reduced, but the light collecting area is diminished
Solution Approach 1:
The patent uses dynamic bias switching to accumulate photons over multiple cycles in a small pixel area. By repeatedly switching between reverse bias (accumulation) and forward bias (readout), the detector can integrate signals from weak light sources over time, compensating for the reduced physical collecting area while maintaining immunity to background light through the selective readout mechanism.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The enhanced DPD achieves sensitivity comparable to SPADs with lower operational voltage and increased flexibility in light detection, allowing for efficient single-photon detection and reduced background noise, making it suitable for integration in single-photon detector arrays.
Implementation Method 1
Incident photons are absorbed in a light absorbing region to generate electron-hole pairs
Implementation Method 2
the eroding of the depleted region by interaction with charge carriers generated in the light absorbing region in response to absorption of photons
Data Source
AI summary
A dynamic photodiode detector or detector array having a light absorbing region of doped semiconductor material for absorbing photons. Electrons or holes generated by photon absorption are detected with a construction of oppositely heavily doped anode and cathode regions and a heavily doped ground region of the same doping type as the anode region. Photon detection involves switching the device from reverse bias to forward bias to create a depletion region enclosing the anode region. When a photon is then absorbed the electron or hole thereby generated drifts under the electric field induced by the biasing to the depletion region where it causes the anode-to-ground current to increase. Furthermore, the detector is configured such that anode-to-cathode current starts to flow once a threshold number of electrons or holes reaches the depletion region, where the threshold may be one to provide single photon detection.