Vertical LEDs on Rigid and Flexible Substrates Using GaN-on-Si Epilayers and Au-Free Bonding

Zou, Xinbo; Zhang, Xu; Chong, Wing Cheung; Tang, Ching Wan; Lau, Kei May

doi:10.1109/ted.2016.2526685

Cited by 17 publications

(11 citation statements)

References 38 publications

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“…The GaN blue LED epilayers were grown on a 6‐inch Si(111) substrate by metal organic chemical vapor deposition (MOCVD). The epilayers include a 1.2‐μm‐thick graded AlGaN buffer layer, a 0.5‐μm‐thick undoped GaN layer, a 2‐μm‐thick Si‐doped n‐type GaN layer, 10 pairs of InGaN/GaN multiple quantum wells (MQWs), and a 0.2‐μm‐thick Mg‐doped p‐type GaN layer in sequence 21 …”

Section: Methodsmentioning

confidence: 99%

Active matrix monolithic micro‐LED full‐color micro‐display

Zhang

Chong

et al. 2020

J Soc Info Display

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An active matrix monolithic micro‐LED full‐color micro‐display with a pixel density of 317 ppi is demonstrated. Starting from large‐scale and low‐cost GaN‐on‐Si epilayers, monolithic 64 × 36 blue micro‐LED arrays are fabricated and further transformed to full‐color micro‐displays by applying a photo‐patternable color conversion layer. This full‐color fabrication scheme shows feasible manufacturability, suggesting a potential for volume production of micro‐LED full‐color micro‐display.

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Section: Methodsmentioning

confidence: 99%

Active matrix monolithic micro‐LED full‐color micro‐display

Zhang

Chong

et al. 2020

J Soc Info Display

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“…This can be attributed to the reason that the whole p-GaN layer is in contact with the Cu layer here, thereby improving the innate high resistivity of the p-GaN, as reported in similar work. 30 Hence, during the design phase of the nanowires, we have further optimized the p-GaN thickness to study the effect of p-GaN thickness on the LEE of nanowire LEDs.…”

Section: Simulation and Device Structurementioning

confidence: 99%

“…Shown in Figure a, LED 2 demonstrated an enhancement in the LEE compared to LED 1 because of the shorter distance between the active region and the Si substrate, consequently stronger reflection from the substrate. When compared to the light-absorptive properties of the silicon material, the flip-chip LEDs with light-reflective mirrors have been reported to have an enhanced LEE. ,, The aforementioned argument has been used to support the fact that LED 3 has a higher LEE compared to LED 2, attributed to the presence of a stronger reflection of light from the metal/Cu substrate and also because of the reduced absorption in Cu as compared to the Si substrate. , The stronger reflection ensures a higher probability of light generated from the active region to be reflected back from the substrate, which is eventually extracted after multiple total internal reflections inside the LED structure. Moreover, the presence of a metal layer in the flip-chip LEDs ensures the formation of a good Ohmic contact at the p-type region , and serves as the optical reflector and the current spreading layer to facilitate the current injection to LED-active regions.…”

Section: Simulation and Device Structurementioning

confidence: 99%

“…When compared to the light-absorptive properties of the silicon material, the flip-chip LEDs with lightreflective mirrors have been reported to have an enhanced LEE. 30,35,36 The aforementioned argument has been used to support the fact that LED 3 has a higher LEE compared to LED 2, attributed to the presence of a stronger reflection of light from the metal/Cu substrate and also because of the reduced absorption in Cu as compared to the Si substrate. 37,38 The stronger reflection ensures a higher probability of light generated from the active region to be reflected back from the substrate, which is eventually extracted after multiple total internal reflections inside the LED structure.…”

Section: ■ Introductionmentioning

confidence: 98%

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Fabrication of Phosphor-Free III-Nitride Nanowire Light-Emitting Diodes on Metal Substrates for Flexible Photonics

Philip¹,

Choudhary²,

Djavid³

et al. 2017

ACS Omega

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In this paper, we report our study on high-performance III-nitride nanowire light-emitting diodes (LEDs) on copper (Cu) substrates via the substrate-transfer process. Nanowire LED structures were first grown on silicon-on-insulator (SOI) substrates by molecular beam epitaxy. Subsequently, the SOI substrate was removed by combining dry- and wet-etching processes. Compared to conventional nanowire LEDs on Si, the nanowire LEDs on Cu exhibit several advantages, including more efficient thermal management and enhanced light-extraction efficiency (LEE) because of the usage of metal reflectors and highly thermally conductive metal substrates. The LED on Cu, therefore, has stronger photoluminescence, electroluminescence intensities, and better current–voltage characteristics compared to the conventional nanowire LED on Si. Our simulation results further confirm the improved device performance of LEDs on Cu, compared to LEDs on Si. The LEE of the nanowire LED on Cu is nine times higher than that of the LED on Si at the same nanowire radius of 60 nm and spacing of 130 nm. Moreover, by engineering the device-active region, we achieved high-brightness phosphor-free LEDs on Cu with highly stable white-light emission and high color-rendering index of ∼95, showing their promising applications in general lighting, flexible displays, and wearable applications.

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“…Lastly, due to the excellent electron transport properties of the two-dimensional electron gas (2DEG), the planar Gunn diode generates a higher oscillation frequency than bulk ones [9][10][11][12]. However, on one hand, the radio frequency (RF) output power of the planar Gunn diode has been predicted to be much lower than the vertical ones [13][14][15]. On the other hand, the fundamental oscillation of Gunn diodes with a channel length of 1-2 µm reported so far have been far from the terahertz regime [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Physical-Based Simulation of the GaN-Based Grooved-Anode Planar Gunn Diode

Wang

2020

Micromachines

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In this paper, a novel gallium nitride (GaN)-based heterostructure Gunn diode is proposed for the first time to enhance the output characteristics of Gunn oscillation waveforms. A well-designed grooved anode contact is adopted to separate the long-channel diode into two short-channel diodes in parallel. If the grooved anode contact is positioned in the middle of the device, the output power nearly doubles in the grooved-anode diode compared with the single-channel ones, as does the output frequency. Based on the numerical results, the best output characteristics are obtained at the 2.0-µm symmetrical grooved-anode diode, which produces nearly 5.48 mW of power at the fundamental frequency of 172.81 GHz, with 3.13% efficiency of power conversion. If the grooved anode contact is not positioned in the middle of the diode, the harmonic frequency would be enhanced. The GaN heterostructure grooved-anode Gunn diode has been demonstrated to be an excellent solid-state source of terahertz oscillator.

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Vertical LEDs on Rigid and Flexible Substrates Using GaN-on-Si Epilayers and Au-Free Bonding

Cited by 17 publications

References 38 publications

Active matrix monolithic micro‐LED full‐color micro‐display

Active matrix monolithic micro‐LED full‐color micro‐display

Fabrication of Phosphor-Free III-Nitride Nanowire Light-Emitting Diodes on Metal Substrates for Flexible Photonics

Physical-Based Simulation of the GaN-Based Grooved-Anode Planar Gunn Diode

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