Yüksek sıcaklık süperiletken bolometre dizilerinde termal bağlaşımın incelenmesi, modellenmesi ve uygulama olanakları

Title:Investigation, modeling, and applications feasibility of the thermal crosstalk in High Tctransition edge bolometer arraysAuthor:Ali BozbeySo far, the high Tc transition edge bolometer (TEB) devices are mostly used as singlepixel detectors. Recently, there are a number of groups working on the 2-4 pixel arrayapplications of the high Tc TEB. Though the target spectrum of the TEB is far IR andmm-waves, we are using a near IR laser source in our investigation due to practicalreasons since the response analysis is similar.We have designed and implemented 4-pixel YBa2Cu3O7-x (YBCO) edge transitionbolometer arrays. The crosstalk study was made possible through the illumination of thesense-devices and measuring the voltage response of the blocked read-out device inthe same array. This was done using a silver coated shadow mask. In order to preventthermal artifacts created by the mask, the mask was made in free standing configurationon top of the devices. The devices were made of 200 nm and 400 nm thick pulsed laserdeposited YBCO films on SrTiO3 and LaAl2O3 substrate materials.In this thesis, we made the qualitative investigation of the dependence of the thermalcrosstalk on the various device parameters such as the substrate material, devicelayout, YBCO film thickness, operating temperature, and modulation frequency. Then,based on the experimental results, we proposed an analytical thermal model. Weproposed two models: i) Basic model, which takes into account only the lateral heatdiffusion in the substrate for quick design purposes ii)Analytical model, which takes intoaccount the lateral heat diffusion, vertical heat diffusion, and the effect of the leakinglaser radiation through the shadow mask, for detailed design purposes and verifying thequalitative analysis. Finally, we proposed and verified possible applications of thethermal crosstalk in TEB arrays. One proposed application of the crosstalk is theelectrical free read-out of the sense pixels by utilization of the unique dependence of themagnitude and phase of the response on the thermal crosstalk between bolometerpixels in an array.The qualitative investigation made in this study is the most detailed investigation aboutthe bolometer arrays and the proposed analytical model is the strongest among thereported ones so far in terms of fitting the experimental results, explaining the effects ofthe various parameters, and designing TEB arrays. The proposed crosstalk based read-out method is expected to decrease the read-out circuitry for possible TEB basedapplications. Since multilayer process is difficult to make in high Tc superconductors,decreasing the complexity of the read-out circuitry by half is even important and it is thefirst time that such a method is utilized including bolometer arrays made of differenttypes of materials.