Resumen
The invention relates to an infrared photodetector containing a region of semiconductor quantum dots (1), n type doped in the barrier region (2), and sandwiched between two layers of semiconductors of n type (3) and p type (4). When infrared photons (5) are absorbed, they create electronic transitions (6) from the confined states in the dots (7) to the conduction band (8). This causes the appearance of a voltage between device p (9) and n (10) contacts or the production of an electrical current. In either way, the detection of the infrared light is possible. A low band-pass filter (12) prevents high energy photons (13) from entering the device and cause electronic transitions (14) from the valence (15) band to the conduction band (8).
Reivindicaciones
1. Infrared photodetector device by means of producing an electric current or a voltage that involves: a semiconductorp -type layer (4), which we call"p- emitter"; a semiconductorn -type layer (3), which we call "n -emitter"; between both of them, one or more quantum dot layers (11) separated among them by layers of semiconductor barrier (2); and where the energy levels corresponding to the confined states in the dots (7) are separated by a zero density of states from the conduction (8) and valence (15) bands and contain both empty states able to receive electrons from the valence band and full states that can pump electrons to the conduction band. 2. Infrared photodetector device, according to claim 1, characterised by the fact that the energy levels corresponding to the electrons confined in the dots (7) originate from a confined potential in the conduction band or the valence band. 3. Infrared photodetector device, according to claims 1 to 2, in which the band structure of the dots is either of type I or type II. 4. Infrared photodetector device, according to claims 1 to 3, in which the barrier or dot regions are doped to fill the confined states with electrons or holes. 5. Infrared photodetector device, according to claim 1 to 4, in which the emitter which receives the IR-radiation in the first place is eitherp -type orn -type. 6. Infrared photodetector device, according to claims 1 to 5, in which the emitter that receives the radiation is covered by a metallization grid that makes the electrical contact and allows the IR-radiation to pass through towards the inner structure. 7. Infrared photodetector device, according to claims 1 to 6, in which the layers that constitute the p- and n- emitter can be substituted byp -type and n-type regions both at the rear side of the device. 8. Infrared photodetector device, according to claims 1 to 7, in which the semiconductor that constitutes the n orp emitters have a higher bandgap than the barrier material. 9. Infrared photodetector device, according to claims 1 to 8, in which ann -type layer can be inserted between the p emitter and the region with quantum dots and the barrier semiconductor layers. 10. Infrared photodetector device, according to claims 1 to 9, in which ap -type layer can be inserted between the n emitter and the region with quantum dots and the barrier semiconductor layers. 11. Infrared photodetector device, according to claims 1 to 10 characterised by the emitter having a surface passivating layer (43) that reduces surface recombination speed. 12. Infrared photodetector device, according to claims 1 to 11 characterised by an IR-radiation back reflector located at the rear side of the device, in order to reflect the non-absorbed photons towards the dot region. 13. Infrared photodetector device according to claims 1 to 12 characterised by a filter (12) that allows only IR-radiation to flow towards the device surface. 14. A method to covert light into electric signals, using the device described in claims 1 to 13, that consists of the following: photons from the IR- radiation to be detected pump electrons (6) from the energy levels created by the confined electrons in the dots, to the higher energy levels, being this transition assisted by electron pumping from the lower energy levels to the energy levels created by the confined electrons in the dots (34), being this last transition, at its time, caused either by a thermal mechanism or by a light source external to the device. 15. Method, according claim 14, in which photons from the IR-radiation to be detected pump electrons from the lower energy levels to energy levels created by the confined electrons in the dots, being this transition assisted by electron pumping from the energy levels created by the confined electrons in the dots to the higher energy levels, being this last transition, at its time, caused either by a thermal mechanism or by a light source external to the device.
