1. A semiconductor-based short wavelength infrared (SWIR) infrared detector sensitive to wavelengths shorter than 2.5 microns comprising:
a stack of semiconductor layers based on III-V materials forming a PIN photodiode, said stack comprising:
a naked electrical contact, called a lower electrical contact, serving as an optical window; and
a detection layer sensitive to said wavelengths, wherein
the lower contact comprises at least one layer of indirect-bandgap III-V material(s) doped n-type, pseudomorphic or lattice matched with a substrate made of a III-V material such as InP or GaAs or of silicon or germanium.
2. The infrared detector according to claim 1, wherein the detection layer is made of GaInAs.
3. The infrared detector according to claim 2, wherein the lower contact comprises an (Al,As,Sb)-based alloy.
4. The infrared detector according to claim 2, wherein the so-called lower contact comprises an AlAs0.563Sb0.437 alloy.
5. The infrared detector according to claim 3, wherein the lower contact comprises at least one alternation of (Al,Ga)AsSb(AlGa)InAs layers.
6. The infrared detector according to claim 5, wherein the alternation of layers comprises at least about ten pairs of (Al,Ga)AsSb and (AlGa)InAs layers.
7. The infrared detector according to claim 1, further comprising:
a layer for matching the conduction bands of the lower contact and the sensitive layer.
8. The infrared detector according to claim 7, wherein the matching layer comprises a set of elementary matching layers comprising an alternation of (Al,Ga)AsSb(Al,Ga)InAs layers.
9. The infrared detector according to claim 1, wherein the detection layer is made of GaAs.
10. The infrared detector according to claim 1, wherein the detection layer is made of InP.
11. The infrared detector according to claim 9, wherein the lower contact comprises at least one layer of AlxGa1-xAs alloy with x lying between 0.42 and 1.
12. The infrared detector according to claim 10, wherein the lower contact comprises an (Al,As,Sb)-based alloy.
13. The infrared detector according to claim 10, wherein the lower contact comprises an AlAs0.563Sb0.437 alloy.
14. The infrared detector according to claim 10, wherein the so-called lower contact comprises at least one alternation of (Al,Ga)AsSb(AlGa)InAs layers.
15. The infrared detector according to claim 10, wherein the lower contact comprises at least about ten pairs of (Al,Ga)AsSb and (AlGa)InAs layers.
16. A fabrication process for fabricating an SWIR infrared detector according to claim 1 comprising:
producing, on the surface of an InP substrate, the lower contact;
producing the detection layer on the surface of the lower electrical contact;
producing a p-type doped upper layer made of a III-V semiconductor and a contact, called the upper contact; and
removing said substrate from the stack produced beforehand.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A semiconductor element, comprising:
a substrate having a pair of main surfaces that face each other;
a semiconductor layer of a first conductivity type on one of the main surfaces of said substrate;
a semiconductor layer of a second conductivity type on said semiconductor layer of the first conductivity type;
an active layer formed between said semiconductor layer of the first conductivity type and said semiconductor layer of the second conductivity type; and
a reflective layer formed on said semiconductor layer of the second conductivity type for reflecting light from said active layer toward said semiconductor layer of the second conductivity type,
wherein the other main surface of said substrate is used as the main light emitting surface,
wherein a translucent conductive layer is formed between said reflective layer and the semiconductor layer of the second conductivity type, and an uneven interface is formed as the interface between said translucent conductive layer and said reflective layer.
2. The semiconductor element according to claim 1 wherein the interface between said translucent conductive layer and said semiconductor layer of the second conductivity type is an approximately flat and smooth surface.
3. The semiconductor element according to claim 1, wherein said uneven surface is provided with inclined surfaces of which the angle of inclination is not greater than 60\xb0 relative to the normal line to the main light emitting surface.
4. The semiconductor element according to claim 1, wherein said uneven surface is in the form of continuous cylindrical lenses.
5. The semiconductor element according to claim 1, wherein said translucent conductive layer is an oxide film that includes at least one of element C selected from a group consisting of at least zinc, indium, tin and magnesium.
6. The semiconductor element according to claim 5, wherein said oxide film includes a trace element D in addition to element C.
7. The semiconductor element according to claim 6, wherein said trace element D is at least one of element selected from among tin, zinc, gallium and aluminum.
8. The semiconductor element according to claim 7, wherein the concentration of said trace element D in the vicinity of the interface between said semiconductor layer and said oxide film is higher than that of the trace element D in the other portion of the film in said oxide film.
9. The semiconductor element according to claim 7, wherein the concentration of said trace element D in the vicinity of the interface between said semiconductor layer and said oxide film is higher than that of said trace element D in the vicinity of the surface opposite to said interface.
10. The semiconductor element according to claim 6, wherein said oxide film includes element D of which the amount is not greater than 20% of the amount of element C.
11. The semiconductor element according to claim 1, wherein said translucent conductive layer is made of ITO.
12. The semiconductor element according to claim 1 wherein said reflective layer includes at least one of element selected from among aluminum, titanium, platinum, rhodium, silver, palladium, iridium, silicon and zinc.
13. The semiconductor element according to claim 1, wherein said reflective layer is a metal film that includes aluminum.
14. The semiconductor element according to claim 1, wherein said reflective layer is made of a dielectric that includes at least any of Si, Zn and Ti.
15. The semiconductor element according to claim 1, wherein the film thickness of said transluent conductive layer is approximately integer times of \u03bb4, wherein the wavelength of light emitted from said active layer is \u03bb.
16. The semiconductor element according to claim 1, wherein the film thickness of said translucent conductive layer is not greater than 1 \u03bcm.
17. The semiconductor element according to claim 1 wherein said reflective layer is also formed in a plane that crosses the main surfaces of substrate.
18. The semiconductor element according to claim 1, wherein at least a portion of the surface of said semiconductor layer that crosses the main surfaces of said substrate is: inclined.
19. The semiconductor element according to claim 1, wherein said semiconductor layer of the first conductivity type is an n-type semiconductor layer and the semiconductor layer of the second conductivity type is a p-type semiconductor layer.
20. The semiconductor element according to claim 1, wherein said semiconductor layer of the first conductivity type and the semiconductor layer of the second conductivity type are nitride semiconductor layers.