Excess noise in InAs/GaSb type-II superlattice pin-photodiodes

• The white noise of InAs/GaSb superlattice infrared pin-photodiodes is investigated.
• Shot-noise model fails to describe noise for diodes with increased dark current.
• McIntyre’s excess noise model fits experimentally observed data very well.
• Avalanche processes are presumably caused by localized high electric field domains.
• Macroscopic defects thus provoke increased dark current and excess noise.

We characterize the low-frequency white noise behavior of a large set of InAs/GaSb superlattice infrared pin-photodiodes for the mid-wavelength infrared regime at 3–5 μm. For diodes with an increased dark current in comparison to the dark current of generation–recombination limited bulk material, the standard shot-noise model fails to describe the noise experimentally observed in the white part of the spectrum. Instead, we find that McIntyre’s noise model for avalanche multiplication processes is compliant with our data. We suggest that within high electric field domains localized around macroscopic defects, avalanche multiplication processes leading to increased dark current and excess noise.