High-power back-to-back dual-absorption germanium photodetector

Area of Science:

• Optoelectronics
• Semiconductor Devices
• Materials Science

Background:

• Photodetectors are crucial components in optical communication systems.
• High-power operation often leads to performance degradation due to space-charge effects.
• Existing photodetector designs struggle to balance high power handling with low noise.

Purpose of the Study:

• To design and fabricate a high-power germanium photodetector.
• To improve high-power characteristics by mitigating space-charge effects.
• To evaluate the performance of the novel photodetector structure.

Main Methods:

• Utilized cold-wall ultrahigh vacuum chemical vapor deposition for fabrication.
• Implemented a back-to-back dual-absorption structure.
• Characterized optical responsivity, dark current, saturated photocurrent, and 3 dB bandwidth.

Main Results:

• Achieved a saturated photocurrent of 21.3 mA at -3V, an improvement from 16.2 mA in typical p-i-n photodetectors.
• Measured a dark current of 1.31 µA at -1V.
• Obtained optical responsivities of 0.31 A/W at 1550 nm and 0.52 A/W at 1310 nm.
• Demonstrated a 3 dB bandwidth of 4.14 GHz at -3V.

Conclusions:

• The back-to-back dual-absorption structure effectively enhances high-power characteristics in germanium photodetectors.
• The fabricated photodetector exhibits promising performance for high-power applications.
• Future optimizations can further improve the 3 dB bandwidth for advanced applications.