Analysis of Undoped and Ag-doped High-Tc YBCO Superconducting Bolometers Fabricated Using a Novel Anti-Reflective Coating and Photolithographic Technique

Abstract

AbstractSuperconducting transition edge bolometers have been fabricated on Ag-doped and undoped YBCO layers on Si(100) substrates using a YSZ buffer layer. We have also fabricated bolometer devices using a stacked-structure of undoped and Ag-doped YBCO material. These thin films were deposited using pulsed laser deposition (PLD). These devices were fabricated using a novel photolithographic/anti-reflective coating (ARC) process. The use of the anti-reflective coating shows no degradation in the overall quality of the superconducting film, but rather it serves as a barrier to moisture, and improves the overall optical collection efficiency of the bolometer device. At a bias of ImA, and chopping frequency of 100Hz, we have measured photoresponse as a function of device temperature, calculated responsivity, and estimated noise equivalent power (NEP) for each of the three device structures. Peak photoresponse, responsivity, and estimated NEP for the undoped bolometer device are 12μV, 0.6mV(W/cm2), and 2.03×103 W/cmHz1/2 respectively. Peak photoresponse, responsivity, and estimated NEP for the Ag-doped bolometer device are 50μV, 2.5mV(W/cm2), and 9.40×10−8 W/cmHz1/2 respectively. Peak photoresponse, responsivity, and estimated NEP for the stacked structure bolometer device are 70μV, 3.5mV(W/cm2), and 1.02× 10−7 W/cmHz1/2 respectively. These results are the first for Ag-doped YBCO bolometers, as well as for superconducting bolometers fabricated using our novel photoresist/anti-reflective coating method.