Schematic illustration (not to scale) of a small section of a 100 or 150 mm diameter SOI wafer: (a) as received from the manufacturer and (b) after etching steps that remove the parts of the handle layer and buried oxide layers underlying the region that will form the thin detector. For the detectors made for the EPI-Hi instrument, the device, buried oxide, and handle-layer thicknesses were 12 (L0 detector) or 25 μm (L1 detector), 0.65, and 500 μm, respectively.