Abstract: An infrared photodetector that is capable of efficiently detecting single photon over an extensive range of wavelengths from several ?m to several hundreds of ?m and is suitable for arraying, and wherein an oscillatory electric field of a single infrared photon (37) parallel to a plane of the patch section (36) of a microstrip antenna when the photon is incident to cause the latter to resonate therewith is converted to an oscillatory electric field (38z) in a z direction, which an electron (39) in a quantum dot (24a) in its base state subband (30) is allowed to absorb, thereby being excited to a first excitation state subband (31) to tunnel through a potential barrier (32) and set free to escape into a quantum well (26) in a ?z direction where it is absorbed. An electric field by ionization of the quantum dot (24a) as a result of escape of the electron (39) causes change in conductance of a point contact (26e).

Abstract: An infrared photodetector that is capable of efficiently detecting single photon over an extensive range of wavelengths from several ?m to several hundreds of ?m and is suitable for arraying, and wherein an oscillatory electric field of a single infrared photon (37) parallel to a plane of the patch section (36) of a microstrip antenna when the photon is incident to cause the latter to resonate therewith is converted to an oscillatory electric field (38z) in a z direction, which an electron (39) in a quantum dot (24a) in its base state subband (30) is allowed to absorb, thereby being excited to a first excitation state subband (31) to tunnel through a potential barrier (32) and set free to escape into a quantum well (26) in a ?z direction where it is absorbed. An electric field by ionization of the quantum dot (24a) as a result of escape of the electron (39) causes change in conductance of a point contact (26e).