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Two-step etch in n-on-p type-II superlattices for surface leakage reduction in mid-wave infrared megapixel detectors

Ramos David, Delmas Marie, Ivanov Ruslan, Žurauskaitė Laura, Evans Dean, Almqvist Susanne, Becanovic Smilja, Hellström Per-Erik, Costard Eric, Höglund Linda

Opto-Electronics Review

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2023

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Vol. 31, Special Issue

art. no. e144556

EN

This work investigates the potential of p-type InAs/GaSb superlattice for the fabrication of full mid-wave megapixel detectors with n-on-p polarity. A significantly higher surface leakage is observed in deep-etched n-on-p photodiodes compared to p-on-n diodes. Shallowetch and two-etch-step pixel geometry are demonstrated to mitigate the surface leakage on devices down to 10 μm with n-on-p polarity. A lateral diffusion length of 16 μm is extracted from the shallow etched pixels, which indicates that cross talk could be a major problem in small pitch arrays. Therefore, the two-etch-step process is used in the fabrication of 1280 × 1024 arrays with a 7.5 μm pitch, and a potential operating temperature up to 100 K is demonstrated.

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High performance type-II InAs/GaSb superlattice infrared photodetectors with a short cut-off wavelength

Delmas Marie, Ramos David, Ivanov Ruslan, Žurauskaitė Laura, Evans Dean, Rihtnesberg David, Almqvist Susanne, Becanovic Smilja, Costard Eric, Höglund Linda

Opto-Electronics Review

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2023

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Vol. 31, Special Issue

art. no. e144555

EN

This work investigates the potential of InAs/GaSb superlattice detectors for the shortwavelength infrared spectral band. A barrier detector structure was grown by molecular beam epitaxy and devices were fabricated using standard photolithography techniques. Optical and electrical characterisations were carried out and the current limitations were identified. The authors found that the short diffusion length of ~1.8 µm is currently limiting the quantum efficiency (double-pass, no anti-reflection coating) to 43% at 2.8 µm and 200 K. The dark current density is limited by the surface leakage current which shows generation-recombination and diffusion characters below and above 195 K, respectively. By fitting the size dependence of the dark current, the bulk values have been estimated to be 6.57·10ˉ⁶ A/cm² at 200 K and 2.31·10ˉ⁶ A/cm² at 250 K, which is only a factor of 4 and 2, respectively, above the Rule07.

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Cryogenic solutions for IR detectors : a guideline for selection

Griot René, Vasse Christophe, Arts Roel, Ivanov Ruslan, Höglund Linda, Costard Eric

Opto-Electronics Review

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2023

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Vol. 31, Special Issue

art. no. e144566

EN

As long as high resolution or long-range observation is to be achieved using infrared detection, it will be necessary to cool down the detector in order to reach the best sensitivity and dynamics. This paper describes different cooling solutions currently used for this purpose discussing advantages and drawbacks. Some guideline is given for cooler choice and selection. The focus is on rotary Stirling coolers illustrated by description of the RMs1 cooler dedicated to high operating temperature size, weight, and power infrared detectors. A user case study is presented with cooler power consumption and cool down time of the RMs1 cooler when integrated in IRnova’s Oden MW IDDCAs.