Interfacial Characteristics of HgCdTe Infrared Detectors Grown on Alternative Substrates

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Physics

Background:

• CdZnTe substrates limit large-format, low-cost HgCdTe infrared focal plane arrays (IRFPAs).
• Epitaxial growth on alternative substrates like GaAs faces challenges due to ~14% lattice mismatch, causing defects and interfacial recombination.
• These defects degrade infrared detector performance.

Purpose of the Study:

• To develop an interface optimization method for HgCdTe/GaAs.
• To improve the performance of GaAs-based HgCdTe infrared detectors by addressing interfacial defects and recombination.

Main Methods:

• Substrate removal using chemical mechanical polishing (CMP) and selective wet chemical etching.
• Surface damage layer elimination with a bromine-based solution (Br2-HBr).
• Simultaneous surface passivation and optical antireflection using a composite dielectric film.

Main Results:

• Average quantum efficiency increased from 58% to 84% (3.5-6.1 μm).
• Blackbody responsivity improved from 8.7 × 10^6 V/W to 1.6 × 10^7 V/W at 80 K.
• Performance reached levels comparable to CdZnTe-based detectors.
• Interfacial optimization reduced surface potential by two orders of magnitude, suppressing recombination.

Conclusions:

• The proposed interfacial optimization method effectively enhances HgCdTe/GaAs detector performance.
• This approach overcomes limitations of alternative substrates, enabling high-performance infrared detectors.
• The optimized interface significantly suppresses recombination, leading to superior quantum efficiency and responsivity.