InAs/GaSb superlattice focal plane arrays for high-resolution thermal imaging

Abstract

The first fully operational mid-IR (3–5 μm) 256×256 IR-FPA camera system based on a type-II InAs/GaSb short-period superlattice showing an excellent noise equivalent temperature difference below 10 mK and a very uniform performance has been realized. We report on the development and fabrication of the detecor chip, i.e., epitaxy, processing technology and electro-optical characterization of fully integrated InAs/GaSb superlattice focal plane arrays. While the superlattice design employed for the first demonstrator camera yielded a quantum efficiency around 30%, a superlattice structure grown with a thicker active layer and an optimized V/III BEP ratio during growth of the InAs layers exhibits a significant increase in quantum efficiency. Quantitative responsivity measurements reveal a quantum efficiency of about 60% for InAs/GaSb superlattice focal plane arrays after implementing this design improvement.

Effect of pressure on electrical properties of short period InAs/GaSb superlattice

“…1 Introduction As a consequence of recent results obtained at low as well as at room temperature [1][2][3][4], InAs/GaSb type-II superlattice (SL) photodiode is now considered as an interesting material system for infrared detectors [5]. Nevertheless, improvement of device technology as well as a better knowledge on material properties of this binary/binary SL photodiodes is still needed to reach performances suitable for third generation IR FPAs.…”

Role of beryllium doping in strain changes in II-type InAs/GaSb superlattice investigated by high resolution X-ray diffraction method

“…Recently, type II InAs/GaSb superlattices were considered as a candidate for third generation infrared detectors [1,2]. It is due to unusual type II band alignment of InAs conduction band and GaSb valence band.…”

Transport measurements on InAs/GaSb superlattice structures for mid-infrared photodiode

“…Thanks to recent results obtained in the mid-infrared domain (MWIR 3-5µm), InAs/GaSb superlattice (SL) is now considered as a new material system 1 for the fabrication of high performance infrared (IR) p-i-n photodiodes suitable for thermal imaging camera 2 . To enhance performances and/or temperature operation, improvements of device technology as well as a better knowledge on fundamental properties of the SL photodiodes are still necessary.…”