Realization of Ultrahigh Quality InGaN Platelets to be Used as Relaxed Templates for Red Micro-LEDs

Bi, Zhaoxia; Lü, Taiping; Colvin, Jovana; Sjögren, Elis; Вайнорюс, Неймантас; Gustafsson, Anders; Johansson, Jonas; Timm, Rainer; Lenrick, Filip; Wallenberg, Reine; Ḿonemar, B.; Samuelson, Lars

doi:10.1021/acsami.0c00951

Cited by 27 publications

(17 citation statements)

References 32 publications

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“…Promising red photoluminescence (PL) results were also reported from relaxed sub‐micrometer InGaN platelets. [ 32 ] Other routes toward the fabrication of relaxed InGaN pursued in the past include deposition on ZnO [ 33,34 ] or ScAlMgO 4 . [ 35,36 ] The low temperatures required for the growth on ZnO and the high n‐type conduction of the InGaN films grown on ScAlMgO 4 when using metal–organic chemical vapor deposition (MOCVD) as the growth technique, however, hampered further development.…”

Section: Introductionmentioning

confidence: 99%

Patterned III‐Nitrides on Porous GaN: Extending Elastic Relaxation from the Nano‐ to the Micrometer Scale

Keller

Pasayat

Gupta

et al. 2021

Physica Rapid Research Ltrs

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Investigations of the use of patterned porous GaN underlayers to achieve elastic relaxation of lattice‐mismatched top layers such as InGaN and AlGaN are reviewed. Thereby, the degree of relaxation of the top layers increases with the porosity and associated decrease in mechanical hardness of the porous GaN underlayers as well as with decreasing pattern size and increase in thickness of the lattice‐mismatched top layers, following the trends observed for nanostructures. Micrometer‐sized, high‐fill‐factor GaN‐on‐porous‐GaN tile arrays are used as universal substrate for the deposition of InGaN and AlGaN. Due to the elastic nature of the relaxation process, the threading dislocation density in the epitaxial material grown on top of the GaN‐on‐porous‐GaN tiles is equivalent to that in the GaN base material. InGaN and AlGaN layers grown on top of relaxed or partially relaxed InGaN or AlGaN underlayers by metal–organic chemical vapor deposition display a higher indium or aluminum content compared to their counterparts deposited on coloaded planar GaN reference wafers due to the decreased lattice mismatch. First applications of the patterned porous GaN‐based technology for optoelectronic and electronic devices are presented and serve as a pathway toward future implementations.

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Section: Introductionmentioning

confidence: 99%

Patterned III‐Nitrides on Porous GaN: Extending Elastic Relaxation from the Nano‐ to the Micrometer Scale

Keller

Pasayat

Gupta

et al. 2021

Physica Rapid Research Ltrs

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“…This configuration has satisfied the needs of most optoelectronic devices for several decades, but it has limitations for many emerging applications where extremely efficient current spreading [ 3–5 ] or unconventional geometries are required. [ 6–10 ] Examples of these applications include not only light emitters such as high‐power blue and ultraviolet vertical III‐nitride LEDs [ 11–17 ] and LEDs for electroluminescent cooling, [ 18 ] but also current collection devices such as carrier‐selective GaAs solar cells. [ 19 ] We have previously suggested diffusion‐driven charge transport (DDCT) as a possible alternative for the DHJ based current injection method to overcome its limitations.…”

Section: Introductionmentioning

confidence: 99%

Back‐Contacted Carrier Injection for Scalable GaN Light Emitters

Kim

Kauppinen

Radevici

et al. 2021

Physica Status Solidi (a)

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It has recently been proposed that back‐contacted III–V light‐emitting diodes (LEDs) could offer improved current spreading as compared to conventional mesa or double side contacted structures. This has inspired also experimental efforts to realize such structures, but fabrication methods for them have not yet been fully established. Herein, the use of unintentionally doped and partially carrier‐selective contacts (SC) is studied to realize back‐contacted indium gallium nitride (InGaN) LEDs. The sharp electroluminescence peak at 439 nm from the multiquantum well stack demonstrates that the approach allows fabricating back‐contacted InGaN LEDs without intentionally doped n‐GaN layers and without inflicting damage in the active region, often observed in alternative approaches relying on lateral doping and the use of high energy particles during fabrication. The samples are fabricated on a finger configuration with several finger widths between 1 and 20 μm. It is observed that the emission spreads most uniformly throughout the structure for fingers with the width of 5 μm. As shown by the simulations, with improved contact resistances, the structures reported herein could enable fabricating back‐contacted LEDs with unity injection efficiency and improved current spreading, offering a path toward large‐area LEDs without contact shading even in materials where n‐doping is elusive.

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“…We have used two different approaches to achieve the flat platelets, either high temperature annealing or chemical mechanical polishing (CMP). [15,40,41] The high temperature annealing under NH 3 protection etches the pyramids from the top apex, while the inclined s-planes stay intact. Annealing for several minutes can result in a thin structure (< 100 nm in thickness) as shown in the SEM image in Fig.…”

Section: Ingan Platelets and Rgb Microledsmentioning

confidence: 99%

“…With both methods, high quality InGaN platelets with indium contents up to 18% can be fabricated with only single bilayer steps on the top c-plane. [15,40] As 18% is the target composition, we have to date not gone beyond 18%. The PL spectra measured at room temperature show full-widths at half-maximum (FWHMs) of 16 nm at 420 nm emission and 25 nm at 480 nm emission.…”

Section: Ingan Platelets and Rgb Microledsmentioning

confidence: 99%

Bottom-up approaches to microLEDs emitting red, green and blue light based on GaN nanowires and relaxed InGaN platelets

Bi¹,

Gustafsson²,

Samuelson³

2023

Chinese Phys. B

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Miniaturization of light-emitting diodes (LEDs) with sizes down to a few micrometers has become a hot topic in both academia and industry due to their attractive applications on self-emissive displays for high-definition televisions, augmented/mixed realities and head-up displays, and also on optogenetics, high-speed light communication. The conventional top-down technology uses dry etching to define the LED size, leading to damage to the LED side walls. Since sizes of microLEDs approach the carrier diffusion length, the damaged side walls play an important role, reducing microLED performance significantly from that of large area LEDs. In this paper, we review our efforts on realization of microLEDs by direct bottom-up growth, based on selective area metal-organic vapor phase epitaxy. The individual LEDs based on either GaN nanowires or InGaN platelets are smaller than 1 μm in our approach. Such nano-LEDs can be used as building blocks in arrays to assemble microLEDs with different sizes, avoiding the side wall damage by dry etching encountered for the top-down approach. The technology of InGaN platelets is especially interesting since InGaN quantum wells emitting red, green and blue light can be grown on such platelets with a low-level of strain by changing the indium content in the InGaN platelets. This technology is therefore very attractive for highly efficient microLEDs of three primary colors for displays.

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Realization of Ultrahigh Quality InGaN Platelets to be Used as Relaxed Templates for Red Micro-LEDs

Cited by 27 publications

References 32 publications

Patterned III‐Nitrides on Porous GaN: Extending Elastic Relaxation from the Nano‐ to the Micrometer Scale

Patterned III‐Nitrides on Porous GaN: Extending Elastic Relaxation from the Nano‐ to the Micrometer Scale

Back‐Contacted Carrier Injection for Scalable GaN Light Emitters

Bottom-up approaches to microLEDs emitting red, green and blue light based on GaN nanowires and relaxed InGaN platelets

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