A structure for detecting electromagnetic radiation having a predetermined wavelength. The structure includes a device wafer having a sensing element disposed on a predetermined region of a surface of the device wafer responsive to the electromagnetic radiation. A cover wafer is provided having a region thereof transparent to the electromagnetic radiation for passing the electromagnetic radiation through the transparent region onto a surface of the sensing element. A bond gap spacer structure is provided for supporting the surface of the sensing element from an opposing surface of the transparent region of the cover wafer a distance less than a fraction of the predetermined wavelength when. the cover wafer is bonded to the device wafer.