Group III-nitride based led having a transparent current spreading layer
A light emitting device has an n-type layer and a p-type layer, which cooperate with one another to form a light generating region. At least one n+ layer is formed upon either the n-type layer or the p-type layer. At least one current spreading layer is formed upon the n+ layer.
1 . A method for forming a light emitting device, the method comprising:
forming a light generating region from two differently doped semiconductor materials;
forming at least one n+ layer upon at least one of the two semiconductor materials; and
forming a current spreading layer upon the n+ layer.
2 . A method for forming a light emitting device, the method comprising:
forming an n-type layer and a p-type layer in a manner such that they cooperate with one another to define a light generating region;
forming at least one n+ layer upon at least one of the n-type layer and the p-type layer; and
forming at least one current spreading layer upon the n+ layer.
3 . The method as recited in claim 2 , wherein at least one of the n-type layer and the p-type layer are formed upon a substrate.
4 . The method as recited in claim 2 , wherein the n+ layer is formed upon the p-type layer and wherein the n-type layer is formed upon a substrate.
5 . The method as recited in claim 2 , wherein the n+ layer is formed upon the n-type layer and wherein the p-type layer is formed upon a substrate.
6 . The method as recited in claim 2 , wherein the n-type layer and the p-type layer comprise AlInGaN.
7 . The method as recited in claim 2 , wherein the n+ layer comprises GaN.
8 . The method as recited in claim 2 , wherein the current spreading layer comprises a conductive oxide layer.
9 . The method as recited in claim 2 , wherein the current spreading layer comprises an indium tin oxide layer.
10 . The method as recited in claim 2 , wherein the current spreading layer comprises a material selected from the group consisting of:
InO x ,
Indium Tin Oxide; and
SnO x .
11 . The method as recited in claim 2 , wherein the current spreading layer comprises a zinc oxide layer.
12 . The method as recited in claim 2 , wherein the current spreading layer comprises a material selected from the group consisting of:
ZnO;
ZnGaO; and
ZnAlO.
13 . The method as recited in claim 2 , wherein the current spreading layer and the n+ layer are substantially transparent to at least one wavelength of visible light.
14 . The method as recited in claim 2 , wherein the sheet resistivity of the current spreading layer is less than approximately 200 ohm/sq.
15 . The method as recited in claim 2 , wherein the sheet resistivity of the current spreading layer is between approximately 10 ohms/cm 2 and approximately 200 ohm/sq.
16 . The method as recited in claim 2 , wherein a thickness of the n+ layer is less than approximately 100 angstroms.
17 . The method as recited in claim 2 , wherein a doping concentration of the n+ is greater than 10 19 cm −3
18 . The method as recited in claim 2 , wherein the conductive oxide layer is in ohmic contact with the n-layer.
19 . The method as recited in claim 2 , wherein the n+ layer cooperates with at least one of the n-type layer and the p-type layer to define a tunneling diode.
20 . The method as recited in claim 2 , wherein a thickness of the oxide layer is an integer number of T, where T is 0.25λnm/n oxide , λ is the emitting wavelength of the light generated from the light emitting device, and n oxide is the refractive index of the oxide material.
21 . The method as recited in claim 2 , wherein the n+ layer is formed at a temperature of less than approximately 900° C.
22 . The method as recited in claim 2 , wherein the n+ layer is formed at a temperature of between approximately 700° C. and approximately 900° C.