Mid-wavelength type II InAs/GaSb superlattice infrared focal plane arrays

Highlights

•The superlattice materials were grown with both GaAs-like and InSb-like interface to balance the strain.

•The pixel was isolated by chlorine-based plasma etching together with citric acid-based chemical wet etching.

•The first device with 50% cutoff wavelength of 4.1 μm shows NETD~18 mK from 77 K to 100 K.

•The NETD of the second device with 50% cutoff wavelength at 5.6 μm is 10 mK at 77 K.

We have demonstrated 384 × 288 pixels mid-wavelength infrared focal plane arrays (FPA) using type II InAs/GaSb superlattice (T2SL) photodetectors with pitch of 25 μm. Two p-i-n T2SL samples were grown by molecular beam epitaxy with both GaAs-like and InSb-like interface. The diode chips were realized by pixel isolation with both dry etching and wet etching method, and passivation with SiN_x layer. The device one with 50% cutoff wavelength of 4.1 μm shows NETD~18 mK from 77 K to 100 K.of the other device with 50% cutoff wavelength at 5.6 μm is 10 mK at 77 K. Finally, the T2SL FPA shows high quality imaging capability at the temperature ranging from 80 K to 100 K which demonstrates the devices’ good temperature performance.

Keywords: Type II InAs/GaSb superlattice;  Focal plane arrays;  Mid-wavelength infrared

Source: Sciencedirect

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