A Rocket-Borne Liquid Helium-Cooled Infrared Telescope. II: Photoconductive Detectors.

Area of Science:

• Astrophysics and Space Science
• Condensed Matter Physics
• Infrared Technology

Background:

• Far-infrared (FIR) detectors are crucial for astronomical observations.
• Extrinsic photoconductive detectors offer high sensitivity in the FIR spectrum.
• Minimizing noise is essential for detecting faint cosmic signals.

Purpose of the Study:

• To investigate the performance of extrinsic photoconductive detectors in the far-infrared spectrum.
• To achieve a high responsivity and low noise equivalent power (NEP) for space-based astronomy.
• To identify the limiting noise sources in Germanium: Gallium (Ge:Ga) detectors.

Main Methods:

• Utilized a low-noise, liquid helium-cooled preamplifier.
• Employed Germanium: Gallium (Ge:Ga) as the extrinsic semiconductor material.
• Designed a specialized instrument for rocket-borne infrared astronomy.

Main Results:

• Achieved a noise equivalent power (NEP) of 10(-14) W Hz(-1/2) at 100 micrometers.
• Demonstrated very high responsivity in the absence of a thermal radiation background.
• Identified generation-recombination noise from other impurities as the limiting factor.

Conclusions:

• Far-infrared extrinsic photoconductive detectors are highly effective for astronomical applications.
• Ge:Ga detectors, when properly cooled and amplified, can achieve state-of-the-art NEP.
• Further research into impurity-related noise is needed to optimize detector performance.