Apparatus for performing wavelength-conversion using phosphors with light emitting diodes

DETAILED DESCRIPTION FIG.
1 illustrates a light-emitting device according to an embodiment of the present invention.
Light-emitting device 100 includes contact layer 110, active region 120, substrate 130, phosphor layer 140 and contact 150.
Active region 120 can further include device layer 121, active layer 122, and device layer 123.
Active region 120 can be any type of layer(s), which through the stimulated emission process, produces light having a particular band of wavelengths.
This particular band of wavelengths can be a subset of a large group of wavelengths that can be produced by a particular active layer.
For example, an active layer 122 constructed of at least Al.
sub.
x Ga.
sub.
1-x N, where x is a value between 0 and 1, can produce light having a band of wavelengths between approximately 300 nanometers and approximately 500 nanometers.
This range of wavelengths (i.
e.
, 300 nm to 500 nm) can be characterized as being between ultraviolet and blue.
Said another way, the group of possible wavelengths produced by active layer 122 can be described as wavelengths producible by an active region constructed of at least Al.
sub.
x Ga.
sub.
1-x N, where x is a value between 0 and 1.
In one embodiment, the active layer 122 can be constructed of at least InGaN/Al .
sub.
x Ga.
sub.
1-x N, device layer 121 can be a p-type AlGaN layer in contact with active layer 122, and device layer 123 can be an n-type AlGaN layer disposed between and in contact with active layer 122 and substrate 130.
This type of active region has been described in previous publications.
The active region 120 can be activated by contact 110 and contact 150 where contact 150 has a ring shape around the device layer 123.
Note that the terms "device layer" and "active layer" each can include multiple layers such as a superlattice structure having multiple layers.
For example, a p-type device layer can comprise multiple layers that overall exhibit a p-type behavior.
Specific to FIG.
1, device layer 121, active layer 122, device layer 123 each can comprise, for example, multiple layers having, for example, a superlattice structure