Efficient surface passivation of germanium nanostructures with 1% reflectance
Tsun Hang Fung1, Joonas Isometsä1, Juha-Pekka Lehtiö2
1Department of Electronics and Nanoengineering, Aalto University, FI-02150 Espoo, Finland.
Nanotechnology
|May 4, 2023
Summary
Researchers developed an effective surface passivation technique for nanostructured germanium (Ge) surfaces, significantly reducing surface recombination velocity (SRV) for enhanced optoelectronic device performance.
Area of Science:
- Optoelectronics
- Materials Science
- Nanotechnology
Background:
- Germanium (Ge) is crucial for near-infrared optoelectronic applications.
- High optical absorption (>99%) in nanostructured Ge (300-1700 nm) is achieved.
- Efficient surface passivation is critical for device performance beyond optics.
Purpose of the Study:
- To identify limiting factors for surface recombination velocity (SRV) in nanostructured Ge.
- To develop an effective surface passivation scheme for nanostructured Ge.
- To demonstrate the impact of passivation on Ge-based optoelectronic devices.
Main Methods:
- Extensive surface and interface characterization using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS).
- Development of a passivation scheme involving atomic-layer-deposited aluminum oxide and chemical treatments.
- Measurement of surface recombination velocity (SRV) and reflectance.
Main Results:
- Identification of key factors limiting SRV in nanostructured Ge.
- Achieved a low SRV of 30 cm/s.
- Obtained low reflectance (~1%) across the ultraviolet to near-infrared spectrum (300-1700 nm).
Conclusions:
- The developed passivation scheme significantly improves nanostructured Ge surfaces.
- Low SRV and reflectance are crucial for advanced Ge optoelectronics.
- This work enables enhanced performance in photodetectors and thermophotovoltaic cells.
