Recent progress in high-temperature superconductor bolometric detectors: from the mid-infrared to the far-infrared (THz) range

Abstract

This paper reviews and summarizes the progress in research on high-T c superconducting infrared bolometers since the discovery of high-temperature superconductor (HTSC) materials. After mentioning previous review articles and their particular themes in the introduction, we recall bolometer basics in section 2, where key parameters are presented and design principles summarized. The latter include incident radiation to HTSC thermometer coupling techniques (absorber and antenna approaches) and the thermal balance inside the active region. Section 3 (which forms the largest part of the article) is devoted to medium and near-infrared transition edge bolometers (0.8-20 µm wavelength range), covering both monolithic and composite (absorber coupled) devices. The main landmarks and state-of-the-art devices are described in the order of the increasing degree of technological complexity (thick substrates, thinned or suspended substrates, micromachined silicon-based structures), while keeping in mind the sensitivity versus time response compromise and the aimed competitiveness with photon detectors. The last section treats far-infrared (antenna coupled) hot electron bolometers (HEBs), whose emergence has benefited from newly developed superconducting nanostructures and which are promising candidates for terahertz heterodyne detection. Finally, recent results on both HTSC and (more mature) low-T c HEBs are given.

Terahertz detectors and focal plane arrays

“…They have not reached high state of technological maturity since their complicated composition does not allow fabrication of very thin layers with high critical temperature. Kreisler and Gau− gue reviewed antenna−coupled high−T c bolometers for both homodyne and heterodyne applications in the FIR and THz frequencies [220,223]. HTSC belongs to the phonon cooled type and electron diffusion mechanism is negligible [209,223,224].…”

“…Kreisler and Gau− gue reviewed antenna−coupled high−T c bolometers for both homodyne and heterodyne applications in the FIR and THz frequencies [220,223]. HTSC belongs to the phonon cooled type and electron diffusion mechanism is negligible [209,223,224]. These receivers are noticeably noisier, compared to low temperature devices, as phonon dynamics play an appreciable role due to the relatively high operating tempe− rature and introduce of excess noise [225,226].…”

THz radiation sensors

“…They cannot be sepa− rated into two classes like low temperature supeconducting (LTSC) HEBs, because they are mainly phonon−cooled de− vices, since the electron−diffusion mechanisms are negligi− ble in HTSC films [144,128]. These receivers are noticeably noisier compared to LTSC devices, phonon dynamics play an appreciable role due to the relatively high operating tem− peratures and introduce excess noise in these devices.…”

“…These receivers are noticeably noisier compared to LTSC devices, phonon dynamics play an appreciable role due to the relatively high operating tem− peratures and introduce excess noise in these devices. Thus, they are not expected to reach the sensitivity of LTSC HEBs [144], but, because of very short electron−phonon relaxation time (t e−ph~1 .1 ps in YBaCuO [145] makes YBaCuO material a good candidate for producing the wide bandwidth devices. Moreover, YBaCuO HTSC HEBs require much higher cooling temperatures of T 80-90 K compared to cooling temperatures of LTSC re− ceivers.…”

Effect of the nano-structure Cu-carbon composite absorber layer on the response of superconductive YBCO TEBs

“…One of the most effective parameters in the sensitivity of these types of detectors is their surface absorption that determines the efficiency of radiation absorption. Typical transition-edge sensors are implemented by thin layer of high-T c superconductor such as YBCO [3]. But due to weak absorption of YBCO material in the IR range [4], these devices typically do not reach their potentially high detectivity values because a little fraction of input power is absorbed by the device when using the bare YBCO film [5].…”