Epitaxial YBa₂Cu₃O_7-y bolometers on micromachined windows in silicon wafers

Epitaxial YBCO thin-film bolometers have been successfully fabricated on thin Si(100) substrates. Substrates included prethinned wafers ranging from 400 μm down to 4 μm thick, and a window, 0.75 μm thick, micromachined into a 400-μm wafer. As the Si is made thinner, the speed and responsivity both improve considerably. A 500-μs rise time was achieved on the micromachined window bolometer (0.75-μm-thick Si) under chopped infrared illumination. Calculations of heat flow in Si windows are in excellent agreement with the observed window-bolometer response waveform.