Performance of an optimized substrate-free focal plane array for optical readout uncooled infrared detector

Abstract

This note presents an optimized substrate-free focal plane array ͑FPA͒, which is implemented in an optical readout uncooled infrared ͑IR͒ detector. The supporting frame of such FPA is a temperature-variable one due to the large decreases in both the heat capacity and the thermal conductance. This brings a unique thermal characteristic: the supporting frame functions as a "thermal isolation" frame which reduces the thermal conductance and therefore increases the temperature change and also functions as a "thermal diffusion" frame which certainly results in the temperature prechange in the ones not absorbing IR radiation. This characterization could significantly increase the temperature change of microcantilevers and therefore improve the performance of the substrate-free FPA. In the proposed IR detector, the fabricated 160ϫ 160 FPA has an average noise equivalent temperature difference ͑NETD͒ and a response time of 330 mK and 16 ms, respectively. The performance of the IR detector theoretically increases by about 5.5 times compared with the one using a substrate FPA. Here, the geometry of the substrate FPA is just the same as the fabricated FPA, but the supporting frame is assumed to be a temperature-constant one. If the optical readout sensitivity can be increased enough using an enhanced IR absorber, the fabricated FPA thus has the potential to achieve a NETD value of 70 mK.

A substrate-free optical readout focal plane array with a heat sink structure

“…Firstly, the substrate-free FPA chip without HSS is prepared, the fabricated processes of the chip have been given in Refs. [14,19] using Au and low stress SiN x OE20 . Secondly, the HSS is fabricated on the frame of the FPA chip.…”

Optimal design of optomechanical uncooled infrared focal plane array with integrated metalens

“…However, the two-layer designs increase the complexity of fabrication due to the multiple sacrificial layer processes, resulting in low yield and high costs. The group of Q. Zhang developed a substrate-free bi-material FPA with optimized multi-fold interval metallized legs [20][21][22]. The multi-fold cantilever was designed with long thermomechanical cantilevers in total length and a decent fill factor.…”

“…Compared with the structures putting all the components on one pixel, it breaks the limit of the pixel size in one direction and provides more freedom for structure designing. However, when there are long cantilevers, the fill factors of both multi-fold structure and nested structure are usually below 50% [20][21][22][23], severely limiting the detector sensitivity. On the other hand, some other researchers enhanced the performance of detectors by finding substitute materials, but always be plagued by manufacturing incompatibilities [24][25][26][27].…”

MWIR room temperature photodetector based on laser-doped silicon carbide

“…5 A number of concepts have been proposed to operate IR photodetectors at or near room temperature. [6][7][8] Apart from photoconductive detectors and photodiodes, three other types of IR photodetectors can operate at near room temperature, which are photoelectromagnetic (PEM) detectors, magnetoconcentration detectors and Dember effect detectors 4 . Auger thermal generation of electrons is suppressed in various non-equilibrium devices, such as excluded photoconductors, extracted photodiodes and magnetoconcentration effect detectors by controlling the minority carrier concentration.…”