Abstract: The invention relates to a radiation-sensitive device comprising a thin radiation-sensitive element (2), in particular a thin photodiode (2). The device includes a substrate (1) on which a photodiode (2) is provided. The surface (5) of the photodiode serves as a semi-pervious mirror (5) through which the radiation (100) enters; a reflecting layer (6) situated between the photodiode (2) and the substrate (1) also serves as a mirror (6). As a result, a so-called resonant cavity effect is possible, resulting, inter alia, in wavelength selectivity of the device. The known device has insufficient wavelength selectivity, which, in addition, cannot readily be set in an accurate and reproducible manner. A device in accordance with the invention is characterized in that the reflecting layer (6) is a metal layer (6) and in that the photodiode (2) is secured to the substrate (1) by means of an adhesive layer (7).