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 4.1μm shows NETD ~18mK from 77K based chemical wet etching.

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

We have demonstrated 384×288 pixels mid-wavelength infrared focal plane arrays (FPA) using type II InAs/GaSb superlattice (T2SL) photodetectors. 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 at 5.6 μm is 10 mK at 77K. Finally, the T2SL FPA shows high quality imaging capability at the temperature ranging from 80K to 100K 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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