A bispectral detector for detecting a first and a second electromagnetic radiation ranges, comprising: - a stack of upper and lower semiconductor layers of a first conductivity type in order to absorb a first and a second electromagnetic radiation ranges respectively, separated by an intermediate layer that forms a potential barrier between the upper and lower layers; - semiconductor zones (44; 20) of a second conductivity type opposite to the first conductivity type and implanted in the upper layer and lower layer, each semiconductor zone in the lower layer being implanted at least partially in the bottom of an opening that passes through the upper layer and intermediate layer; and - electrical conductor elements (28, 30, 32, 34) connected respectively to semiconductor zones (44; 20) in order to collect the electrical charges in these zones; characterised: - in that at least that part of each opening that passes through upper layer is separated from said upper layer by a semiconductor cap layer of the second conductivity type: ▪ whereof the concentration of dopants of the second conductivity type is greater than 10 17 cm -3; and ▪ whereof the thickness is chosen as a function of said concentration so that it exceeds the minority carrier diffusion length in the cap layer; - in that every semiconductor zone of the second conductivity type:in the upper layer forms with an adjacent semiconductor zone of the second conductivity type:of the lower layer a continuous volume; - and in that the intermediate layer is made of a material that is insulating with respect to the materials of the upper and lower layers or is made of a semiconductor material of the first conductivity type, whereof the band gap is more than three times that of each of the upper layer and lower layer. - a stack of upper and lower semiconductor layers of a first conductivity type in order to absorb a first and a second electromagnetic radiation ranges respectively, separated by an intermediate layer that forms a potential barrier between the upper and lower layers; - semiconductor zones (44; 20) of a second conductivity type opposite to the first conductivity type and implanted in the upper layer and lower layer, each semiconductor zone in the lower layer being implanted at least partially in the bottom of an opening that passes through the upper layer and intermediate layer; and - electrical conductor elements (28, 30, 32, 34) connected respectively to semiconductor zones (44; 20) in order to collect the electrical charges in these zones; - in that at least that part of each opening that passes through upper layer is separated from said upper layer by a semiconductor cap layer of the second conductivity type: ▪ whereof the concentration of dopants of the second conductivity type is greater than 10 17 cm -3; and ▪ whereof the thickness is chosen as a function of said concentration so that it exceeds the minority carrier diffusion length in the cap layer; ▪ whereof the concentration of dopants of the second conductivity type is greater than 10 17 cm -3; and ▪ whereof the thickness is chosen as a function of said concentration so that it exceeds the minority carrier diffusion length in the cap layer; - in that every semiconductor zone of the second conductivity type:in the upper layer forms with an adjacent semiconductor zone of the second conductivity type:of the lower layer a continuous volume; - and in that the intermediate layer is made of a material that is insulating with respect to the materials of the upper and lower layers or is made of a semiconductor material of the first conductivity type, whereof the band gap is more than three times that of each of the upper layer and lower layer.