LIGHT-EMITTING DEVICE
A light-emitting device according to the present invention includes a plurality of columnar semiconductors 30 arranged on a GaN substrate 7 , and a plurality of protrusions 13 formed on a side face of each columnar semiconductor 30 . Each columnar semiconductor 30 has a light-emitting portion composed of a nitride compound semiconductor, and is supported by the GaN substrate 7 at a lower end. The columnar semiconductor 30 has a multilayer structure including an n-cladding layer 9 , an active layer 10 , and a p-cladding layer 11 , the active layer 10 having a multi-quantum well structure in which In W Ga 1-W N (0<W<1) well layers and GaN barrier layers are alternately deposited.
1 . A light-emitting device comprising:
at least one columnar semiconductor having a light-emitting portion composed of a nitride compound semiconductor;
a plurality of protrusions formed on a side face of the columnar semiconductor; and
a p electrode and an n electrode for supplying a current to the light-emitting portion,
wherein,
each of the plurality of protrusions is composed of a material having a larger band gap than a band gap of the nitride semiconductor in the light-emitting portion.
2 . (canceled)
3 . The light-emitting device of claim 1 , wherein each of the plurality of protrusions has a size of no less than 5 nm and no more than 500 nm along a direction perpendicular to an axial direction of the columnar semiconductor.
4 . The light-emitting device of claim 3 , wherein the columnar semiconductor has a multilayer structure including an n-cladding layer, a p-cladding layer, and an active layer provided between the n-cladding layer and the p-cladding layer, the active layer functioning as the light-emitting portion.
5 . The light-emitting device of claim 1 , comprising a plurality of said columnar semiconductors, and a substrate supporting the plurality of columnar semiconductors.
6 . The light-emitting device of claim 5 , wherein the substrate is composed of a nitride compound semiconductor.
7 . The light-emitting device of claim 5 , wherein a phosphor material is provided in between the plurality of columnar semiconductors.
8 . The light-emitting device of claim 7 , wherein the phosphor material absorbs at least a portion of light which is emitted from the columnar semiconductor, contains a phosphor which emits light having a longer wavelength than a wavelength of the light, and is filled in between the columnar semiconductors.
9 . The light-emitting device of claim 8 , wherein one of the p electrode and the n electrode covers the plurality of columnar semiconductors and the phosphor material.
10 . The light-emitting device of claim 5 , comprising: at least one first conductive layer connected to the p electrodes of the plurality of columnar semiconductors; and at least one second conductive layer connected to the n electrodes of the plurality of columnar semiconductors.
11 . The light-emitting device of claim 10 , wherein the first conductive layer and the second conductive layer serve also as, respectively, a plurality of p electrodes and a plurality of n electrodes.
12 . The light-emitting device of claim 11 , wherein the phosphor material is located between a plane which is defined by the first conductive layer and a plane which is defined by the second conductive layer.
13 . The light-emitting device of claim 1 , wherein each of the plurality of columnar semiconductors has a length of no less than 1×10 2 nm and no more than 1×10 5 nm along an axial direction.
14 . A light-emitting device comprising:
a substrate;
a plurality of columnar semiconductors arranged on the substrate, each having a light-emitting portion composed of a nitride compound semiconductor;
a plurality of protrusions formed on a side face of each columnar semiconductor;
a phosphor material being filled in between the plurality of columnar semiconductors and being in contact with the columnar semiconductors;
a first electrode layer covering the phosphor material and the plurality of columnar semiconductors and being electrically connected to one end of each columnar semiconductor; and
a second electrode layer being electrically connected to another end of each columnar semiconductor.
15 . An illumination device comprising:
the light-emitting device of claim 1 ; and
a circuit for controlling emission of light by the light-emitting device.