Near-infrared germanium PIN-photodiodes with >1A/W responsivity

Area of Science:

• Semiconductor physics
• Optoelectronics
• Materials science

Background:

• Near-infrared (NIR) detection is crucial for many applications.
• Current NIR detectors face limitations in spectral responsivity or material cost and compatibility.
• Germanium (Ge) is a CMOS-compatible material with potential for optoelectronic devices.

Purpose of the Study:

• To develop a high-performance, CMOS-compatible NIR photodiode using germanium.
• To achieve high external quantum efficiency (EQE) over a wide spectral range.
• To reduce optical and electrical losses in germanium photodiodes.

Main Methods:

• Fabrication of a nanoengineered PIN-photodiode using CMOS-compatible germanium.
• Minimization of optical losses through surface nanostructures.
• Reduction of electrical losses via atomic-layer-deposited aluminum oxide passivation and dielectric-induced electric field carrier collection.

Main Results:

• Verified external quantum efficiency (EQE) exceeding 90% for wavelengths between 1.2-1.6 µm at room temperature and zero bias.
• High responsivity of 1.15 A/W at 1.55 µm.
• Exceptional spectral response range, with EQE over 100% below 300 nm.
• Low dark current density of 76 µA/cm² at -5 V bias, lower than previously reported for Ge photodiodes.

Conclusions:

• The nanoengineered Ge PIN-photodiode demonstrates state-of-the-art performance for NIR detection.
• The device is CMOS-compatible, offering a cost-effective alternative to III-V materials.
• This advancement has significant implications for the design and manufacturing of germanium photodiodes and NIR detection technologies.