Ultrathin high efficiency ultraviolet leds

Abstract

Ultraviolet (UV) or far-UV light-emitting diodes (LEDs), laser diodes (LDs) or other light-emitting devices, with a thickness of less than 1000 nm for the n-type cladding layer, active region, and p-type cladding layer, wherein the efficiency of the UV or far-UV LEDs, LDs, or other light emitting devices, is improved through the reduction of morphological degradation through stress relaxation.

Description

[0001] ULTRATHIN HIGH EFFICIENCY ULTRAVIOLET LEDS

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit under 35 U. S. C. Section 119(e) of the following co-pending and commonly-assigned application:

[0003] U. S. Provisional Patent Application Serial No. 63 / 755,607, filed on February 7, 2025, by Michael Wang, Wenting Gong, Shuji Nakamura and James S. Speck, entitled ‘“ULTRATHIN HIGH EFFICIENCY ULTRAVIOLET LEDS,” docket number G& C 30794.0867USP1 (UC-2025-375-1);

[0004] which application is incorporated by reference herein.

[0005] This application is related to the following co-pending and commonly-assigned applications:

[0006] P. C. T. International Patent Application Serial No. PCT / US26 / 13459, filed on February 2, 2026, by Michael Wang, Wenting Gong, Shuji Nakamura and James S. Speck, entitled “NON-COALESCED ISLAND HOLE INJECTION STRUCTURE FOR ULTRAVIOLET LIGHT-EMITTING DIODES,” docket number G& C 30794.0866WOU1 (UC-2025-371-2), which application claims the benefit under 35 U. S. C. Section 119(e) of co-pending and commonly-assigned U. S. Provisional Patent Application Serial No. 63 / 752,109, filed on January 31, 2025, by Michael Wang, Wenting Gong, Shuji Nakamura and James S. Speck, entitled “NON-COALESCED ISLAND HOLE INJECTION STRUCTURE FOR ULTRAVIOLET LIGHTEMITTING DIODES,” docket number G& C 30794.0866USP1 (UC-2025-371-1);

[0007] which applications are incorporated by7reference herein.

[0008] BACKGROUND OF THE INVENTION

[0009] 1. Field of the Invention.

[0010] This invention relates to a novel design for ultraviolet (UV) or far-UV lightemitting diodes (LEDs). In these devices, the semiconductor layer structures of the UV LED are ultrathin, which decreases the relaxation of the layers and increasesmaterial quality, improving the performance and light extraction of the devices. Therefore, these devices are superior to the prior art which do not make use of the improved material quality of thinner material layers.

[0011] There is a strong desire for efficient UV LED devices. Wavelengths below 300 nm are universally germicidal so that UV disinfection is considered one of the most promising means to fight pandemic disease outbreaks, improve hygiene of water supplies and medical settings, and improve protocols for disinfection of air and surfaces. Other applications of UV light include short-range optical communication, 3D printing, epoxy curing, therapeutic uses, and many others.

[0012] The current state of the art in UV LEDs remains about a factor of five less energy-efficient, and a factor of 10-100 more expensive (in per Watt terms) than Hg-vapor lamp sources. On the other hand, solid-state semiconductor LED based UV light sources are expected to provide many benefits including miniaturization, rapid on / off and dimming for smart functionality, wavelength tunability', durability, and low power consumption. In the future, it is anticipated that UV LEDs will achieve similar efficiency and cost to their blue and white LED counterparts (which vastly outperform all other visible light emitting technologies), and the market for UV LEDs will grow rapidly. In order to achieve increased market share and improved global health outcomes, novel technologies for efficient UV LEDs are needed.

[0013] 2. Description of the Related Art.

[0014] Ill-mtride semiconductors are often used for UV LEDs. As used herein, the terms “Group-Ill nitride,” “Ill-nitride,” or “nitride,” refer to any alloy composition of (Al, Ga, In, B, Sc, Y)N semiconductors having the formula ScjYmGanAlxInyBzN where 0<j<l, 0<m<l, 0<n<l, 0<x<l, 0<y<l, 0<z<l, and j+m+n+x+y+z=l.

[0015] The usefulness of gallium nitride (GaN). aluminum nitride (AIN) and their ternary and quaternary compounds incorporating aluminum and indium (AlGaN, InGaN, AlInGaN), has been well established for the fabrication of visible and ultraviolet optoelectronic devices and high-power electronic devices. These devicesare typically grown epitaxially using metalorganic chemical vapor deposition (MOCVD), hydride vapor phase epitaxy (HVPE), molecular beam epitaxy (MBE), or other methods.

[0016] The development of AlGaN for short wavelength devices in the UV spectrum between 190 nm to 380 nm enabled ITI-nitride-based light emitting diodes (LEDs) and laser diodes (LDs) to overtake many other research ventures. Consequently, III-nitride-based UV LEDs have begun to overtake conventional Hg vapor lamps as the dominant light source for disinfection in some applications such as portable consumer devices and point-of-use water disinfection. The expected market for UV disinfection products is expected to grow significantly in the coming years, but previous UV LED technologies are not yet efficient or inexpensive enough to compete with Hg-based lamps. Technological advances in UV LED efficiency and output power are needed to address worldwide water insecurity, improve health outcomes in developing and developed nations alike, and to address the rapidly growing consumer, enterprise, and public demand for disinfection products. Other novel applications, such as nanolithography, curing, dermatological therapeutics, and many others are also expected to benefit from improved UV LED performance. Finally, far UV-C light (<225 nm) has been shown to not be carcinogenic or cataractogenic while still being strongly absorbed by DNA and RNA, creating a plethora of novel disinfection applications for AlGaN-based devices.

[0017] UV LEDs typically include at least one n-type region, p-type region, and active region. The active region further comprises light-emitting regions (quantum wells) and confinement structures (quantum barriers, spacers, carrier blocking layers, and other structures). Herein, the combination of the light-emitting regions and confinement structures will be referred to as the active region. Each of these semiconductor layers is in principle capable of emitting light, but highly efficient LED operation results when the vast majority of the light is emitted in the quantum wells, so these will be referred to as the light-emitting regions herein. Light emission from the other structures such as doped layers or confinement structures can in somecases be measurable but is usually considered detrimental to LED efficiency as the recombination in these regions is parasitic on the preferred recombination pathway taking place in the quantum wells.

[0018] The external quantum efficiency (EQE) or total efficiency (i / z.) of LEDs is defined as the total rate of photon emission from the device divided by the rate of injection of electrical carriers into the device, and can be expressed by the following equation:

[0019] Y]L= / rad inj jext

[0020] where the light extraction efficiency, i, is defined as the fraction of photons emitted out of the packaged device to those produced within the semiconductor layers, the injection efficiency, tjinj, is defined as the fraction of electron-hole pairs recombining in the active region as opposed to recombining elsewhere in the device, and the radiative efficiency, rjrad (also known as internal quantum efficiency or IQE), is defined as the fraction of electron-hole pairs recombining in the active region of the device, which recombine radiatively, as opposed to non-radiatively.

[0021] UV LEDs can be improved in two major ways: improving the radiative efficiency by improving the light emitting region and carrier injection, or improving the light extraction efficiency by decreasing the optical absorbance of all layers. The growth of high efficiency devices using the AlGaN material system, especially with an Al concentration above 30%, remains a challenge, because current Al GaN-based UV emitters suffer from extremely inefficient radiative carrier recombination due to highly defective material from the use of thick n-cladding and p-cladding layers. The present invention addresses this issue by the use of ultrathin layers, to avoid material quality degradation due to stress relaxation in thicker layers.SUMMARY OF THE INVENTION

[0022] The objective of this invention is to enhance the light output power of III-nitride-based light emitting devices, such as LEDs, and especially UV LEDs, by improving the material quality of the semiconductor films in the device. Improving the material quality leads to an improvement in the energy efficiency of the III-nitride-based light emitting devices, enabling the expansion of Ill-nitride-based semiconductor device applications into various commercial products.

[0023] In the prior art, conventional UV LEDs comprise many semiconductor layers deposited epitaxially on or above a substrate. These layers may include at least: n-type material, an active region comprising quantum barriers and wells, an electron blocking layer, and a p-t pc material. These layers are ty pically grown by MOCVD or some other epitaxial method in an n-down configuration, meaning that the n-type layers are deposited first, and the active and p-type layers are afterwards deposited on or above the n-type layers. This disclosure will assume such an n-down configuration unless otherwise specified, such that terms such as “below” could be understood to mean “to the n-side of’, and “above” can be understood to mean “on the p-side of', in some contexts.

[0024] The present invention discloses a device, such as a Ill-nitride LED, and a method of fabricating the device, including an active region having a single or multiple quantum well structure emitting at an ultraviolet (UV) wavelength between 190 to 380 nm, positioned between at least an n-type cladding layer and a p-type cladding layer, wherein a total thickness of material between a bottom of the n-type cladding layer and a top of the p-type cladding layer is less than 1000 nm.

[0025] The Ill-nitride “films”, “layers”, or “structures” disclosed herein may individually or commonly comprise multiple layers or islands having varying or graded compositions, a heterostructure comprising layers of dissimilar (Al, Ga, In, B, Sc, Y)N composition, or one or more layers of dissimilar (Al, Ga, In, B, Sc, Y)N composition. It is to be understood that films referred to as AlGaN films are referred to in such a way for simplicity, with the implicitunderstanding that the real device may include some In, B, Sc, Y, or any other element without departing from the scope of the present embodiment. For example, a variation of the present invention including Ill-nitride structures with AlGalnN or AlGaBN is understood to be within the scope of this disclosure.

[0026] The Tll-nitride structures disclosed herein may comprise unintentionally doped or intentionally doped structures, with elements such as iron, magnesium, silicon, germanium, oxygen, carbon, and / or zinc, even if not specified directly. The structures may be formed by methods including but not limited to MOCVD. HVPE. or MBE.

[0027] The structures may further comprise Ill-nitride layers grown in any crystallographic Ill-nitride direction, such as on a conventional c-plane oriented crystal, or on a nonpolar plane such as a-plane or m-plane, or on any semipolar plane.

[0028] A first Ill-nitride semiconductor device of the present invention comprises a UV LED structure, with a sapphire (either flat sapphire, or patterned sapphire) substrate, and AlxGayInzN layers where x+y+z=l and x<l, y<l, z<l. In one embodiment, the LED structure includes an AIN buffer; an ALGai-aN buffer where 0.75<a<l; an n- type AlbGai-bN cladding where 0.45<b<0.85 and preferably where 0.55<b<0.75; an active region comprising multiple different layers of ALGai-cN quantum barriers and AlaGai-dN quantum wells where 0.6<c<l and 0. l<d<0.7; a p-type AlcGai-cN electron blocking layer (EBL) where 0.6<e<l; a p-type cladding layer that comprises a short period superlattice (SPSL) comprised of alternating layers of AlfGai-fN and AlgGai-gN where 0.6<f<l and 0<g<0.4. a p-t pe doped bulk AlhGai-hN layer where 0<h<l, and / or a three-dimensional (3D) polarization-doped AliGai-iN layer where 0<i<l, and / or a non-coalesced island hole injection structure comprising a p-type doped AljGai-jN where 0<j<0.2.

[0029] The non-coalesced island hole injection structure comprises one or more noncoalesced islands of Ill-nitride material adjacent to or within the p-type region, e.g., the p-type cladding layer, wherein the Al composition of the non-coalesced island hole injection structure is less than the Al composition of adjacent portions of the p-type region, and the non-coalesced island hole injection structure does not fully cover the p-type region.

[0030] The non-coalesced island hole injection structure is further described in the cross-referenced applications set forth above, namely co-pending and commonly-assigned P. C. T. International Patent Application Serial No. PCT / US26 / 13459, filed on February 2, 2026, by Michael Wang, Wenting Gong, Shuji Nakamura and James S. Speck, entitled “NON-COALESCED ISLAND HOLE INJECTION STRUCTURE FOR ULTRAVIOLET LIGHT-EMITTING DIODES / ’ docket number G& C 30794.0866WOU1 (UC-2025-371-2), which application claims the benefit under 35 U. S. C. Section 119(e) of co-pending and commonly-assigned U. S. Provisional Patent Application Serial No. 63 / 752,109, filed on January 31, 2025, by Michael Wang, Wenting Gong. Shuji Nakamura and James S. Speck, entitled “NON-COALESCED ISLAND HOLE INJECTION STRUCTURE FOR ULTRAVIOLET LIGHTEMITTING DIODES,” docket number G& C 30794.0866USP1 (UC-2025-371-1), which applications are incorporated by reference herein.

[0031] Moreover, a tunnel junction layer grown on or above the p-type cladding layer may be substituted for the non-coalesced island hole injection structure.

[0032] The n-type cladding layer is doped with silicon at a concentration between 1x1017cm’3to 1x1021cm’3, and more preferably the n-type cladding layer is doped with silicon at a concentration between 5xl018cm’3to 5xlO20cm’3.

[0033] The n-type cladding layer and the active region are grown using MOCVD at a V / III ratio less than 1000, including a first embodiment wherein the n-type cladding layer and the active region are grown using MOCVD at a V / III ratio less than 100, and a second embodiment wherein the n-type cladding layer and the active region are grown using MOCVD at a V / III ratio less than 30.

[0034] The p-type cladding is grown using MOCVD at a V / III ratio less than 20000. including an embodiment wherein the p-type cladding is grown using MOCVD at a V / III ratio less than 10000. The p-type cladding layer is doped with magnesium at a concentration between IxlO17cm” to IxlO21cm’3, and more preferably wherein the p-type cladding layer is doped with magnesium at a concentration between 5x1018cm'3to 5xlO20cm'3.

[0035] The total thickness of the n-type cladding layer is between 100 to 500 nm, including an embodiment wherein the n-type cladding layer is less than 300 nm in thickness.

[0036] The total thickness of the active region is betw een 50 to 300 nm, and more preferably the active region is less than 150 nm in thickness.

[0037] The total thickness of the p-type EBL is between 1 to 20 nm

[0038] The total thickness of the p-type cladding layer is between 10 to 300 nm, including an embodiment wherein the p-type cladding layer is less than 150 nm in thickness.

[0039] In the case of a p-type cladding layer of thickness between 180-300 nm, the total thickness of the n-type cladding is between 100 to 500 nm, the total thickness of the p-type EBL is betw een 1 to 20 nm, and the total thickness of the active region is between 50 to 180 nm. The total thickness of the p-type cladding layer from the highest point of the non-coalesced island hole injection structure to the bottom of the p-type SPSL is between 10 to 300 nm. Therefore, the total thickness of the structure between the bottom of the n-type cladding layer to the top of the p-type cladding layer is less than 1000 nm.

[0040] As noted above, the p-type cladding may comprise a 3D polarization-doped layer of AliGai-iN where 0<i<l, and having a thickness less than 300 nm, where the composition throughout the layer can be constant or varied. A possibility for a varied composition profile would be a linearly increasing or decreasing Al composition between the start of the 3D polarization-doped layer and the end of the layer. The layer may also be undoped, or doped with magnesium, beryllium, or other elements, at an average concentration between 1016to 1021cm'3. The doping concentration profile may be constant or varied throughout the layer. Some examples of possible varied doping concentration profiles are a linearly increasing or decreasing amount of dopant, or a constant low or zero doping concentration for most of the layer with afew thin (less than 10 nm thick) sheets of extremely high concentrations (delta doping).

[0041] A second Ill-nitride semiconductor device of the present invention comprises the same structure as the first Ill-nitride semiconductor device of the present invention, without the non-coalesced island hole injection structure.

[0042] A third Ill-nitride semiconductor device of the present invention comprises the same structure as the first III -nitride semiconductor device of the present invention, without the non-coalesced island hole injection structure, and with a tunnel junction layer substituting for the non-coalesced island hole injection structure. The tunnel junction layer comprises multiple semiconductor layers of a total thickness preferably less than 500 nm, and its thickness is not counted towards the 1000 nm limit of the layers in between the bottom of the n-type cladding layer and the top of the p-l pe cladding layer.

[0043] It is understood that additional metallic contact layers or protective ceramic layers may be present on or around the device. It is also understood that all the aforementioned layers may be patterned and / or shaped to enhance light extraction of the device and / or current injection to the device.

[0044] BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Referring now to the drawings in which like reference numbers represent corresponding parts throughout:

[0046] Fig. 1 is a cross-sectional schematic of the first nitride semiconductor device of the present invention, comprising a p-type cladding layer with a non-coalesced island hole injection structure.

[0047] Fig. 2 is a cross-sectional schematic of the second nitride semiconductor device of the present invention, comprising a p-type cladding layer without a noncoalesced island hole injection structureFig. 3 a cross-sectional schematic of the third nitride semiconductor device of the present invention, comprising a tunnel junction layer above the p-type cladding layer.

[0048] DETAILED DESCRIPTION OF THE INVENTION

[0049] In the following description of the preferred embodiment, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration a specific embodiment in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural and compositional changes may be made without departing from the scope of the present invention.

[0050] Overview

[0051] The present invention describes a Ill-nitride-based UV light emitting device, such as an LED, including an active region having a single or multiple quantum well structure emitting at a UV wavelength between 190 to 380 nm, positioned between at least an n-type cladding layer and a p-type cladding layer, wherein a total thickness of material between a bottom of the n-type cladding layer and a top of the p-t pe cladding layer is less than 1000 nm. The use of this structure in UV light emitting devices offers a means of improving the Ill-nitride-based UV light emitting device performance

[0052] Technical Description

[0053] The prior art in UV LEDs ty pically comprises an n-type cladding that is typically above 500-1000 nm thick to increase current spreading. High Al content AlGaN, especially when doped n-type with silicon for conductivity, morphologically degrades significantly with thicker growth. Thinner UV LED structures can provide the benefit of improved morphology7and lower defect density, while maintaining high conductivity7through extremely high silicon doping concentrations. In addition, withthe onset of large morphological degradation at approximately 1000 nm, it is preferable to grow the entire structure of the LED from the n-type cladding to the p-type cladding under 1000 nm. In current state-of-the-art, commercially available UV LEDs, this has not widely been implemented.

[0054] Embodiment 1

[0055] Fig. 1 is a schematic sectional view showing the structure of a Ill-nitride semiconductor light emitting diode device (an LED device) according to the first embodiment of the present invention. This LED comprises a sapphire (either flat sapphire, or patterned sapphire) substrate 102, and deposited successively in the following order on the substrate 102 are the following layers:

[0056] a first buffer layer 103 comprised of AIN (closest to the substrate 102 surface); a second buffer layer 104 comprised of ALGai-aN where 0.75<a<l;

[0057] an n-type cladding layer 105 comprised of AlbGai-bN where 0.45<b<0.85, and preferably where 0.55<b<0.75;

[0058] an active region 101 comprising a multiple quantum well structure comprised of ALGai-cN quantum barriers and AlaGai-aN quantum wells where 0.6<c< 1 and 0.1<d<0.7, and preferably where 0.6<c<0.8 and 0.3<d<0.6;

[0059] a p-type ALGai-cN EBL 106 where 0.6<e<l; and

[0060] a p-type cladding layer 107 comprising:

[0061] an SPSL comprised of alternating layers of AlfGai-fN and AlgGai-gN where 0.6<f<l and 0<g<0.4;

[0062] a bulk layer comprised of AlhGai-hN where 0<h<l; and / or a 3D polarization-doped layer comprised of AkGai-iN where 0<i<l; and / or

[0063] a non-coalesced island hole injection structure 108 comprising p-type AljGai-jN where 0<j<0.2, but more generally may comprise AlxGayIni-x-yN where x<0.2 and y>0.8, and preferably x<0.1 andy>0.9.The non-coalesced island hole injection structure 108 comprises one or more non-coalesced islands of Ill-nitride material adjacent to or within the p-typc cladding layer 107, wherein the Al composition of the non-coalesced island hole injection structure 108 is less than the Al composition of the adjacent portions of the p-type cladding layer 107, and the non-coalesced island hole injection structure 108 does not fully cover the adjacent portions of the p-t pe cladding layer 107.

[0064] With regards to layer compositions, the following are applied:

[0065] • In all the above described layers. 0<a,b,c,d,e.f.g.h,i,j<l, and each of a. b, c, d, e, f, g, h, i, j, can be different from one another.

[0066] • The composition of the 3D polarization-doped AliGai-iN layer throughout the layer can be constant or varied. A possibility for a varied composition profile would be a linearly increasing or decreasing Al composition between the start of the 3D polarization-doped layer and the end of the layer.

[0067] With regards to doping concentrations, the following are applied:

[0068] • The n-type cladding layer 105 is doped with an n-type dopant, preferably silicon, to a concentration between IxlO17cm’3to IxlO21cm’3, and preferably, between 5xl018cm’3to 5x102° cm’3.

[0069] • The p-type cladding 107 is undoped or doped with a p-type dopant, such as magnesium, beryllium, or other elements, wherein the SPSL has a dopant concentration of between IxlO17cm’3to IxlO21cm’3, and preferably between 5xl018cm’3to 5x1020cm’3, and the 3D polarization-doped AkGai-iN layer has an average dopant concentration of between IxlO16cm’3to IxlO21cm’3.

[0070] • The doping concentration profile of the 3D polarization-doped AliGai-iN layer may be constant or varied throughout the layer. Some examples of possible varied doping concentration profiles are a linearly increasing or decreasing amount of dopant, or a constant low or zero doping concentration for most of the layer with a few thin (less than 10 nm thick) sheets of extremely high concentrations (delta doping).

[0071] With regards to layer thicknesses, the following are applied:• The n-type cladding layer 105 preferably has a thickness between 100 to 500 nm, and preferably between 100 and 300 nm.

[0072] • The active region 101 preferably has a thickness between 50 to 300 nm, and preferably has a total thickness between 50 and 150 nm.

[0073] • The p-type EBL 106 has a thickness of between 1 and 20 nm.

[0074] • The p-type cladding 107 preferably has a thickness between 10 and 300 nm, and preferably has a thickness between 20 and 60 nm.

[0075] • The 3D polarization-doped AhGai iN layer has a thickness between 10 and 300 nm.

[0076] • The non-coalesced island hole injection structure 108 has a thickness between 10 and 100 nm, and preferably has a thickness less than 30 nm.

[0077] • Thus, a total thickness between the bottom of the n-type cladding layer 105 and the top of the p-type cladding layer 107 is less than 1000 nm, and preferably between 200 and 700 nm. Alternatively, when the non-coalesced island hole injection structure 108 is present within the structure, a total thickness between the bottom of the n-type cladding layer 105 and the top of the p-type cladding layer 107 including the non-coalesced island hole injection structure 108 is also less than 1000 nm, and preferably between 200 and 700 nm.

[0078] Embodiment 2

[0079] Fig. 2 is a schematic sectional view showing the structure of a Ill-nitride semiconductor light emitting diode device (an LED device) according to the second embodiment of the present invention. This device comprises the same structure as the first Ill-nitride semiconductor device of the present invention, with the removal of the non-coalesced island hole injection structure 108.

[0080] Embodiment 3

[0081] Fig. 3 is a schematic sectional view showing the structure of a nitride semiconductor light emitting diode device (an LED device) according to the thirdembodiment of the present invention. This device comprises the same structure as the first nitride semiconductor device of the present invention, with the replacement of the non-coalesced island hole injection structure 108 with a tunnel junction structure 109. The tunnel junction structure 109 comprises multiple semiconductor layers of a total thickness preferably less than 500 nm, and more preferably less than 300 nm, and its thickness is not counted towards the 1000 nm limit of the layers in between the bottom of the n-type cladding layer 105 and the top of the p-type cladding layer 107.

[0082] Advantages and Improvements

[0083] With the decreased thickness of the epitaxial layers of the LED, the active region is more coherently strained to the template material due to less stress relaxation with material growth. This decreases defect generation in the material and thus decreases the defect density in the emitting region, resulting in a higher internal quantum efficiency in the emitting region and increased LED efficiency.

[0084] Conclusion

[0085] This concludes the description of the preferred embodiment of the present invention. The foregoing description of one or more embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.

Claims

WHAT IS CLAIMED IS:

1. A device, comprising:a IILnitride light-emitting diode (LED), including an active region having a single or multiple quantum well structure emitting at an ultraviolet (UV) wavelength between 190 to 380 nm, positioned between at least an n-type cladding layer and a p-type cladding layer, wherein a total thickness of material between a bottom of the n-type cladding layer and a top of the p-type cladding layer is less than 1000 nm.

2. The device of claim 1, wherein the LED is comprised of AlxGayInzN where x+y+z=l and 0<x<l, 0<y<l, 0<z<l.

3. The device of claim 1, wherein the n-type cladding layer comprises AlbGai-bN where 0.45<b<0.85, and preferably where 0.55<b<0.75.

4. The device of claim 1, wherein the n-type cladding layer is doped with silicon at a concentration between IxlO17cm'3to IxlO21cm'3, and preferably the n-type cladding layer is doped with silicon at a concentration between 5xl018cm'3to 5xl020cm'3.

5. The device of claim 1, wherein the n-type cladding layer has a thickness between 100 to 500 nm, and preferably has a thickness between 100 to 300.

6. The device of claim 1, wherein the active region has a thickness between 50 to 300 nm, and preferably has a thickness between 150 and 150 nm.

7. The device of claim 1, wherein the n-type cladding layer and the active region are grown using MOCVD at a V / III ratio less than 1000, including a first embodiment wherein the n-type cladding layer and the active region are grown using MOCVD at a V / III ratio less than 100, and a second embodiment wherein the n-type cladding layer and the active region are grown using MOCVD at a V / III ratio less than 30.

8. The device of claim 1, wherein the p-type cladding is grown using MOCVD at a V / III ratio less than 20000, including an embodiment wherein the p-type cladding is grown using MOCVD at a V / III ratio less than 10000.

9. The device of claim 1, wherein the p-type cladding layer is doped with magnesium at a concentration between IxlO17cm’3to IxlO21cm’3, and preferably wherein the p-type cladding layer is doped with magnesium at a concentration between 5xl018cm’3to 5xlO20cm’3.

10. The device of claim 1, wherein the p-type cladding layer comprises:a short period superlattice (SPSL) comprised of alternating layers of AlfGai-fN and AlgGai-gN, where 0.6<f<l, and 0<g<0.4;a p-type doped bulk AlhGai-hN layer where 0<h<l; and / ora three-dimensional (3D) polarization-doped AliGai-iN layer where 0<i<l.

11. The device of claim 10, further comprising a non-coalesced island hole injection structure comprising p-type doped AljGai-jN where 0<j<0.2, wherein the noncoalesced island hole injection structure comprises one or more non-coalesced islands of III-ni tride material adjacent to or within the p-type cladding layer, an Al composition of the non-coalesced island hole injection structure is less than the Al composition of adjacent portions of the p-type cladding layer, and the non-coalesced island hole injection structure does not fully cover the adjacent portions of the p-type cladding layer.

12. The device of claim 11, wherein the non-coalesced island hole injection structure has a thickness between 10 and 100 nm, and preferably has a thickness less than 30 nm.

13. The device of claim 1, wherein the p-type cladding layer has a thickness between 10 and 300 nm, including an embodiment wherein the p-type cladding layer has a thickness between 20 and 60 nm.

14. The device of claim 1, further comprising a tunnel junction grown on or above the p-type cladding layer, with a thickness of the tunnel junction is less than 1000 nm and includes an embodiment with a thickness of the tunnel junction less than 500 nm.

15. A method, comprising:fabricating a Ill-nitride light-emitting diode (LED), including an active region having a single or multiple quantum well structure emitting at an ultraviolet (UV) wavelength between 190 to 380 nm, positioned between at least an n-type cladding layer and a p-type cladding layer, wherein a total thickness of material between a bottom of the n-type cladding layer and a top of the p-type cladding layer is less than 1000 nm.

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