A device for detecting a chemical species, including a Geiger-mode avalanche diode, which includes a body of semiconductor material delimited by a front surface. The semiconductor body includes: a cathode region having a first type of conductivity, which forms the front surface; and an anode region having a second type of conductivity, which extends in the cathode region starting from the front surface. The detection device further includes: a sensitive structure arranged on the anode region and including at least one sensitive region, which has an electrical permittivity that depends upon the concentration of the chemical species; and a resistive region, arranged on the sensitive structure and electrically coupled to the anode region.