Epitaxial YBa2Cu3O7−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.