High-performance GeSi/Ge multi-quantum well photodetector on a Ge-buffered Si substrate

Area of Science:

• Optoelectronics
• Materials Science
• Semiconductor Physics

Background:

• Photodetectors are crucial for optical communication and infrared sensing.
• Germanium-Silicon (GeSi) alloys offer tunable bandgaps for infrared applications.
• Developing cost-effective, high-performance photodetectors compatible with silicon fabrication is essential.

Purpose of the Study:

• To demonstrate a high-performance photodetector utilizing a GeSi/Ge multi-quantum well (MQW) structure.
• To evaluate the photodetector's performance characteristics, including dark current, responsivity, and temperature coefficient of resistance (TCR).
• To assess the potential of this CMOS-compatible structure for short-wave infrared (SWIR) and uncooled infrared imaging.

Main Methods:

• Fabrication of PIN mesa photodetectors with a 4-cycle Ge0.86Si0.14/Ge MQW structure.
• Growth of the MQW structure using reduced pressure chemical vapor deposition (RPCVD) on a Ge-buffered Si (100) substrate.
• Characterization of device performance under varying bias conditions and wavelengths, including dark current, optical responsivity, and temperature coefficient of resistance.

Main Results:

• Achieved low dark current density of 3 mA/cm² at -1 V bias.
• Demonstrated optical responsivities of 0.51 A/W at 1310 nm and 0.17 A/W at 1550 nm, with a cutoff wavelength of 1620 nm.
• Observed a high temperature coefficient of resistance (TCR) of -5.18%/K, exceeding commercial thermal detectors.
• Confirmed good high-power performance and repeatable light response.

Conclusions:

• The fabricated Ge0.86Si0.14/Ge MQW photodetector exhibits high performance suitable for SWIR detection.
• The device's high TCR suggests potential for uncooled thermal infrared imaging applications.
• The CMOS-compatible and low-cost nature of the GeSi/Ge multilayer structure makes it a promising candidate for future integrated optoelectronic systems.