Longwave IR lattice matched L-valley Ge/GeSiSn waveguide quantum cascade detector

Area of Science:

• Optoelectronics
• Materials Science
• Semiconductor Physics

Background:

• Group-IV materials offer a pathway to integrated photonic devices.
• Longwave infrared (LWIR) detection is crucial for various applications.
• Existing group-IV photodetectors have limitations in spectral range.

Purpose of the Study:

• To propose and analyze a lattice-matched Germanium/Germanium-Silicon-Tin (Ge/GeSiSn) quantum cascade detector (QCD).
• To achieve LWIR operation using intersubband transitions within the L-valley.
• To extend the spectral response beyond current group-IV photodetectors.

Main Methods:

• Utilized N-doped quantum wells (QWs) within a waveguided lattice-matched structure.
• Deposited the structure strain-free on a Germanium (Ge) buffer on a Silicon (Si) substrate.
• Optimized the QCD design by analyzing photoresponsivity and detectivity (D*).

Main Results:

• Demonstrated a photovoltaic mode QCD with tunable spectral response from 9 to 16 µm.
• Achieved optical absorption and carrier transport via intersubband transitions in the L-valley.
• The proposed QCD shows potential for significantly extended spectral range.

Conclusions:

• The Ge/GeSiSn QCD is a promising device for LWIR detection.
• This technology can surpass the performance of group-IV photodiodes and photoconductors.
• Applications include imaging, sensing, lidar, and fiber/space communications.