Thermal budget simulations and device performance of microstructured high-T/sub c/ transition edge bolometers on silicon

Abstract

Silicon represents the material of choice for fast superconducting high quality transition edge bolometers. The performance of these devices sensitively depends on their thermal properties where the heat flux critically affects time constant, optical response and noise behavior. In this work extensive numerical Finite Elementcalculations have been performed for various bolometer configurations, using the ABAQUS-code. A high degree of t h e r m a l i s o l a t i o n c a n b e e s t a b l i s h e d t h r o u g h microstructuring techniques. The bolometric performance of a prototype device is compared with the simulated data.Values of the detectivity D* as high as 1~1 0 '~ cm HzH W 1 already should be feasible, while a time constant in the regime below 10 ms would be retained.degree of thermal isolation of the device from the heat sink [l]. Technologically, this is achieved through a very thin membrane type silicon substrate, where the heat flux is reduced, for example, through a microstructured meandering configuration. The high-T, superconductor-silicon system, however, poses a number of technological challenges, particularly in connection with the required multilayer system. It consists of a silicon membrane substrate, a dielectric lattice matched buffer layer, the thin superconducting film, an additional passivation layer and, finally, an optical absorber film on top of the structure. Critical design parameters are illustrated in eqn 1, where the bolometric response So is shown as a function of the temperature increase AT from the incoming radiation, the optical absorptance q, the bias current i, the resistive temperature coefficient p of the superconducting film, and its resistance r.

Thermoelectric and Bolometric Infrared Microsensors

“…Therefore, high-D Ã HTSC bolometers based on this well-established technology will have a better chance of replacing other thermal infrared sensors or quantum detectors in numerous technical applications than other types of HTSC bolometers. If the present fully suspended Si membrane is replaced by a membrane structured in a meandering line with only one suspension point, thus achieving maximal thermal isolation, future D Ã values will reach about 10 10 cm Hz 1/2 aW with a change in time constant to 7 ms as thermal budget simulations have revealed [85]. They were fabricated on 1 mm thick single crystalline (100)-oriented Si membranes fully suspended to the surrounding silicon frame.…”

Thermal budget calculations, design aspects, and device performance of high-Tc air-bridged microbolometers

“…It is composed of a 500-A thick yttria stabilized ZrO buffer layer and a 350-A thick YBa Cu 0 superconducting film. Specific thermal parameters of the materials system, i.e., density, specific heat, and thermal conductivity values, have been taken from the literature [6]. Fig.…”

“…The resistor structure has been arranged with two different total lengths, but otherwise identical properties. A finite element calculation scheme, described in more detail in [6], has been used for the simulation. Convective heat transport to the surroundings, radiative losses, and interfacial thermal resistance effects have been neglected in the calculations.…”