Status of Cooled and Uncooled Infrared Detectors at SCD, Israel

Abstract

For the highest end mid-wave-infrared applications, SCD, France offers a family of cryogenically cooled detectors with background limited performance (BLIP). The matured InSb planar technology is implemented in a variety of focal plane arrays, from a 320 x 256 format with a 30 µm pitch to a 1280 x 1024 format with a 15 µm pitch, all of which are operated at 77K. A major challenge is to reduce the cooling requirements. Then substantial reductions in size, weight, and power (SWaP) can be achieved by using a smaller cooler and Dewar assembly. SCD's new epi-InSb detectors, grown by molecular beam epitaxy, have a BLIP temperature of ~100 K at F/3. This enhanced operating temperature reduces the required cooling power by ~20 % compared with the conventional 77 K operation. For a very high operating temperature, we have developed the new XBn-InAsSb detector with a 4.2 µm cut-off wavelength. This detector exhibits a BLIP temperature of ~160K at F/3 and a reduction in cooling power of ~60 %. These HOT detectors enable an improved range of solutions, including faster cool-down time and mission readiness, longer mission times, and higher cooler reliability. We can also exploit their reduced dark current to obtain an enhanced signal to noise ratio at lower operating temperatures.The well-established 25 µm pitch family of uncooled µ-Bolometer detectors has two basic formats, 384 x 288 and 640 x 480, and several sensitivity grades. The very high sensitivity 25 µm pitch detector has been demonstrated at F/2.4 for mid-range systems. The wide-band detector is optimized for both the long-wave-infrared and mid-waveinfrared spectral bands. Recently we developed the new 17 µm pitch family of detectors. The 640 x 480 format is a leading candidate for applications such as thermal weapon sights, driver vision enhancers and other mid-range IR systems. The 17 µm family is currently being expanded with the high sensitivity grade and with the addition of two new formats: the compact 384 x 288 for low SWaP applications, and the large 1024 x 768 format for applications requiring high resolution and a wide field of view.

Gas mixture influence on the reactive ion etching of InSb in an inductively coupled methane-hydrogen plasma

“…The dark current density characteristics were measured at 77 K and are shown as a dashed line in figure 2(b). With a value as low as 32 nA cm −2 at −50 mV, this device is state of the art for InSb epi-diode technology [3].…”

“…All those objectives will require several improvements concerning both the fabrication of the material and the device. For the InSb material, structures grown by molecular beam epitaxy (MBE) have demonstrated the ability to obtain very high material quality [2], resulting in an increase in the operation temperature by 15 K [3]. In addition, the MBE growth technique allows the elaboration of a new generation of InSb photodetectors such APDs [4,5] or heterojunction designs [6,7].…”

Compact thermal modeling of microbolometers

“…Another MEMS device is a micro bolometer which is used for sensing infrared radiation. Formerly, mainly because of their price, they were used predominantly in military applications, however now they became affordable and soon they could be even integrated as standard devices with portable devices allowing low cost thermal imaging [1]- [2].…”