Pixel of microdisplay having integrated catadioptric light extraction system
Disclosed is a unit pixel of a microdisplay having a concave reflector with a center aperture. The light extractor has a protrusion and a bulk portion formed using the same epitaxial growth process. The concave reflector with a center aperture is formed on the protrusion, and epitaxial growth of the light-emitting body is made through the aperture concave reflector. In addition, the light rays reflected by the concave reflector with a center aperture has exit angles that are nearly perpendicular to the exit surface and are thus easily emitted to the outside.
1 . A pixel of a microdisplay comprising:
a light extractor having a compound semiconductor and having a hemispherical protrusion and a bulk portion having the same material as the protrusion;
a reflector with a center aperture formed on a surface of the protrusion; and
a light emitting body formed on the reflector with the center aperture and a single crystal grown from the light extractor to form light of a specific wavelength,
wherein the hemispherical protrusion has a convex shape toward the light emitting body, the light of the specific wavelength formed at the light emitting body passes the center aperture and the light passing through the center aperture is directed toward the light extractor through reflections at the hemispherical inner surface of the reflector contacted with the hemispherical protrusion.
2 . The pixel of a microdisplay of claim 1 , wherein the light extractor is doped n-type, and the light-emitting body forms visible light or ultraviolet light.
3 . The pixel of a microdisplay of claim 1 , wherein the reflector with the center aperture has a concave shape toward the light extractor, and the central portion of the reflector with the center aperture is open.
4 . The pixel of a microdisplay of claim 1 , wherein the reflector with the center aperture has a uniform thickness.
5 . The pixel of a microdisplay of claim 1 , wherein the reflector with the center aperture has a non-uniform thickness and is formed to fill space between the protrusion and the light emitting body.
6 . A pixel of a microdisplay comprising:
a light extractor having a hemispherical protrusion made of a GaN material and a bulk portion having the same material as the protrusion;
a reflector with a center aperture formed on a surface of the protrusion; and
a light-emitting body formed on the reflector with the center aperture for forming light of a first wavelength and light of a second wavelength longer than the first wavelength,
wherein the hemispherical protrusion has a convex shape toward the light emitting body, the lights of the first wavelength and the second wavelength formed at the light emitting body passes the enter aperture and the light passing through the center aperture is directed toward the light extractor through reflections at the hemispherical inner surface of the reflector contacted with the hemispherical protrusion.
7 . The pixel of a microdisplay of claim 6 , wherein the light extractor is doped n-type.
8 . The pixel of a microdisplay of claim 6 , wherein the reflector with the center aperture has a concave shape toward the light extractor, and the central portion of the reflector with the center aperture is open.
9 . The pixel of a microdisplay of claim 8 , wherein the reflector with a center aperture has SiO 2 or Al 2 O 3 .
10 . The pixel of a microdisplay of claim 8 , wherein the reflector with the center aperture has a uniform thickness.
11 . The pixel of a microdisplay of claim 8 , wherein the reflector with the center aperture has a refractive index that is larger than the refractive index of air and smaller than the refractive index of GaN.
12 . The pixel of a microdisplay of claim 8 , wherein the reflector with the center aperture has a non-uniform thickness and is formed to fill a space between the surface of the protrusion and the light-emitting body.
13 . The pixel of a microdisplay of claim 6 , wherein the light emitting body includes,
a first light-emitting diode formed on the reflector with the center aperture, and generating the light of the first wavelength; and
a second light-emitting diode formed on the first light emitting diode and generating the light of the second wavelength.
14 . The pixel of a microdisplay of claim 13 , wherein the light emitting body further includes a third light-emitting diode that is formed on the second light-emitting diode and generates light of a third wavelength that is longer than the second wavelength,
wherein the light of the first wavelength is blue light, the light of the second wavelength is green light, and the light of the third wavelength is red light.