Substrate and device pattern dependence of the thermal crosstalk in Y Ba2Cu 3O7−δ transition edge bolometer arrays

Abstract

Using YBa2CU3O7-delta (YBCO) thin films, pulsed laser deposited on 1-mm-thick LaAlO3 or SrTiO3 substrates, we made 4 x 1 pixel arrays of transition edge bolometers with separations between neighboring pixels ranging from 40 mu m to 170 mu m for testing purposes. We investigated the effects of the YBCO film thickness (200 and 400 nm), substrate material, and back-etching of the substrate, on the crosstalk between the pixels of the arrays. The investigation was based on the analysis of the voltage response of the de current biased bolometers versus the modulation frequency of a near-infrared laser source. We observed that the bolometer arrays made of 400-nm-thick films had less interpixel thermal crosstalk than the 200-nm-thick films. The effect of substrate thickness on the response of the pixels was investigated by up to 500 mu m back-etching of the substrates. The bolometers made on back-etched LaAlO3 substrates had anomalous crosstalk response behavior, which was effective at higher modulation frequencies. In addition, we present an analytical thermal model for explaining the observed effects of the thermal crosstalk on the response characteristics of the pixels of the arrays. We report the measured response and the anticipated thermal crosstalk of the characterized bolometers'. We describe the responses based on the thermal models and discrepancies from the model's predictions.