Blue-light-enhanced avalanche photodiode with a multi-finger grating structure for fluorescence detection

Area of Science:

• Optoelectronics
• Semiconductor Devices
• Photonics

Background:

• Photodetector responsiveness is crucial for fluorescent fiber optical temperature sensor accuracy.
• Traditional photodiodes (PDs) have low gain and signal-to-noise ratio (SNR), limiting high-precision detection.
• Existing photodetectors struggle to meet the demanding requirements of advanced sensing applications.

Purpose of the Study:

• To develop a novel multi-finger grating (MFG) avalanche photodiode (APD) to overcome limitations of traditional PDs.
• To enhance the conversion capability and responsiveness of photodetectors for improved sensing.
• To investigate the performance of MFG APDs in fluorescence detection applications.

Main Methods:

• Device principle simulated and verified using technology-computer-aided design (TCAD).
• Fabrication of standard grating APD (SG-APD) and multi-finger grating APDs (2FG-APD, 3FG-APD, 4FG-APD) using a 0.18 µm CMOS process.
• Establishment of an optoelectronic test platform to analyze device characteristics.

Main Results:

• The MFG structure significantly enhances photodetector conversion capability.
• At 480 nm, responsivity increased by 79.3% (2FG-APD), 96.9% (3FG-APD), and 70.2% (4FG-APD) compared to SG-APD.
• The 3FG-APD demonstrated a strong photon response in the blue light spectrum.

Conclusions:

• The novel MFG APD design effectively improves photodetector performance.
• The 3FG-APD shows particular promise for blue light detection in fluorescence sensing.
• This device holds significant potential for applications in fluorescence detection and high-precision sensing systems.