Patent ID: 8618622

Claim:
A backlit detector for the detection of electromagnetic radiation around a predetermined wavelength, including: a semiconductor absorption layer for the absorption of said radiation, formed above a medium at least partially transparent to said radiation, and having a thickness capable of transmitting at least some of said radiation; and a mirror placed above the semiconductor layer to reflect radiation received therethrough, wherein it comprises, placed between the mirror and the semiconductor layer, a periodic grating of metallic patterns, the mirror and the periodic grating being included in a layer of material at least partially transparent to said radiation and formed on the semiconductor layer, and wherein the mirror and the periodic grating of metallic patterns are designed to verify the following relations: d â‰¤ Î» Re â¡ ( n 1 ) Î» 16 Ã— Re â¡ ( n 2 ) + m Ã— Î» 2 Ã— Re â¡ ( n 2 ) â‰¤ h â‰¤ 3 Ã— Î» 8 Ã— Re â¡ ( n 2 ) + m Ã— Î» 2 Ã— Re â¡ ( n 2 ) Re â¡ ( n 2 ) â‰¤ 1 , 3 Ã— Re â¡ ( n 1 ) Re â¡ ( n 1 ) â‰¥ Re â¡ ( n substrat ) where Re denotes the real component; d is the distance between the semiconductor layer and the periodic grating, h is the distance between the mirror and the periodic grating, m is a positive or null integer, Î» is a wavelength at which the semiconductor layer is absorbent, n 1 is the refractive index of the semiconductor layer, n 2 is the refractive index of the layer in which the periodic grating and the mirror are formed; and n substrat is the refractive index of the medium above which the semiconductor absorption layer is formed.