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

Abstract

Effect of the nano-structure Cu-carbon composite absorber layer on the response of superconductive YBCO TEBs Abstract. We have used a nanostructure copper composite layer as the absorber for infrared radiation on superconductive YBCO bolometers. The Cu composite has the advantage of having little destructive effects on superconductive YBCO material and its deposition process is done at low temperature. The bolometer is made of 200nm thick YBCO film on 1mm thick LaAlO 3 and SrTiO 3 crystalline substrates, deposited using pulsed laser deposition technique. The Cu composite layers were made by decomposition of C 2 H 2 and co sputtering of Cu target in an RF system. The layer was deposited on an insulating buffer layer of diamond like carbon (DLC). The spectral absorption of the Cu composite layer was also measured through measurements of the spectral transmission and reflection of the layer on various substrates. The control of the absorption of the composite layer versus Cu composition has been achieved and presented here. In addition, optimization of the Cu component of the absorber layer for maximum increase of the response of the detectors as well as its effects on the response characteristics of the devices are presented in this paper. IntroductionSuperconductor transition-edge sensors are one of the most sensitive radiation detectors in the range of infrared to far infrared [1,2]. 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]. Therefore, surface coating is essential for increasing infrared response of these devices, particularly in the micrometer wavelength range.One of the major hinders of using absorber layers for the superconducting ETBs is due to their destructive effects on the electrical properties of the superconducting YBCO material. For example, they can cause lowering of the critical temperature T c or smoothening the transition curve. Smoothening and widening transition curve is an undesirable effect, which reduces peak value in dR/dT curves and hence reducing the IR response [6]. In this work, we introduce a novel absorber, which was coated using a low temperature process and had very little destructive effect on our bolometer device. The absorber, used in this work, is a copper-carbon nano-composite that is coated in a low temperature planar magnetron sputtering process, where we have control over the percentage of copper composition in the deposited absorber layer. As we show in this paper, the absorption coefficient of this film is strongly dependent on Cu composition, leading to the control of the absorption coefficient.

Compound Hertzian chain model for copper–carbon nanocomposites' absorption spectrum

“…By simultaneous solution of coupled equations (1) experimental results are published previously [14]. Here, we used the DLC absorption spectrum to eliminate its effect of the optical absorption of nanoparticle network.…”

“…For particle size in the range of nanoparticles, the absorption could not thoroughly be associated to skin effect because the dimensions of the particles are well below the range of skin depth [6]. Especially, in addition, previously published experimental data show that the absorption spectrum of the copper nanoparticle Compound Hertzian Chain Model for CopperCarbon Nanocomposites' Absorption Spectrum Alireza Kokabi, Mehdi Hosseini, Saman Saeedi, Ali Moftakharzadeh, Mohammad Ali Vesaghi, and Mehdi Fardmanesh > REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERE TO EDIT) < 2 network of Cu-C composite layer does not completely match to the spectrum governed by electron-surface scattering [14].…”

Digital implementation of the capacitively coupled electrical substitution for resistive bolometers

“…In order to obtain the best intrinsic responsivity of a bolometer, one will choose the best materials based upon their availability and the compatibility of their fabrication processes: resistive material with the highest temperature coefficient of resistance (TCR) for the sensing resistor-VOx [2], high-temperature superconductors (YBCO) or manganese films (LCMO, LSMO) [7,8]-absorbing material with the highest absorption coefficient (η) at the infrared wavelength target range for the absorbing layer-black gold [9,10], nanostructured materials [11]-structural material with the lowest thermal mass C th and thermal conductance G thpolymers, polyimide [12]. Once the materials are selected, one will also develop the best geometries or structures to optimize, i.e.…”