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US-20260130008-A1 - PLASMONIC MICRO-LEDS FOR HIGH SPEED COMMUNICATION

US20260130008A1US 20260130008 A1US20260130008 A1US 20260130008A1US-20260130008-A1

Abstract

A method for fabricating a high-speed semiconductor device, the method comprising the steps of: providing a light emitting device structure on substrate, activated p-doped; etching grooves on the p-doped layer, partially or fully filling the grooves with noble metal; and constructing at least one top emitting flip chip light emitting device and/or at least one bottom emitting flip chip light emitting device.

Inventors

  • Bilal JANJUA
  • Hossein FARIBORZI
  • Mohsen ASAD

Assignees

  • HYPERLUME INC.

Dates

Publication Date
20260507
Application Date
20250223

Claims (20)

  1. 1 . A method for fabricating a semiconductor device, the method comprising the steps of: providing a substrate; patterning nanoholes through a p-doped GaN layer down towards a multiple quantum well (MQW) emitting region of a noble metal; depositing a nanostructured noble metal film in the nanoholes.
  2. 2 . The method of claim 1 , wherein the texturing comprises etching.
  3. 3 . The method of claim 1 , wherein the holes are at least one of a vertical or angled profile.
  4. 4 . The method of claim 1 , wherein the semiconductor device comprises a plasmonic III-Nitride device epi-structure.
  5. 5 . The method of claim 4 , wherein the plasmonic III-Nitride device structure comprises a plasmonic region comprising the nanoholes and an electronic region free of the nanoholes.
  6. 6 . The method of claim 1 , further comprising a step of maximizing a near-field coupling between the multiple quantum well (MQW) emitting region and the p-GaN layer/noble metal interface supporting a surface plasmon when a distance between the near-field coupling and the multiple quantum well (MQW) emitting region is minimized.
  7. 7 . The method of claim 6 , wherein the distance of plasmonic nanoparticle from the nearest quantum well of the multiple quantum well (MQW) emitting region is less than a penetration depth of the surface plasmon.
  8. 8 . The method of claim 7 , wherein the distance of plasmonic nanoparticle from the nearest quantum well of the multiple quantum well (MQW) emitting region is less than about 50 nm at wavelength of about 450 nm.
  9. 9 . The method of claim 8 , wherein the p-GaN layer is thicker than a depletion width on a p-side of the diode to facilitate carrier transport.
  10. 10 . The method of claim 9 , wherein the p-GaN layer is approximately more than 50 nm with sufficient doping levels in the p and n regions.
  11. 11 . The method of claim 6 , wherein the nanostructured noble metal film couples the surface plasmon to increase radiative recombination rates without sacrificing significantly p-contact resistance.
  12. 12 . The method of claim 1 , wherein the semiconductor device comprises at least one of a buffer layer, a superlattice strain relief layer, a low doped high material quality n-doped layer, a high doped low temperature grown p-doped layer, a heavily doped high temperature grown p-doped layer, and an aluminum gallium nitride based larger bandgap electron blocking layer.
  13. 13 . A method for fabricating a semiconductor device, the method comprising the steps of: providing a substrate; activating a top p-doped layer comprising at least one step of metal deposition, rapid thermal annealing and chemical wet etching; etching features into the p-doped layer using a thin dielectric and resist as a mask; depositing a passivation layer and/or a noble metal into the etched features; and fabricating the semiconductor device a flip chip bonding process.
  14. 14 . The method of claim 13 , comprising a further step of etching the features into the p-doped layer with various 3D geometric shapes to improve plasmonic coupling.
  15. 15 . The method of claim 13 , comprising a further step of etching the features into the p-doped layer with a positive angle profile for closer proximity to at least one quantum well.
  16. 16 . The method of claim 13 , comprising a further step of etching the features into the p-doped layer with a negative angle profile for a reduced semiconductor/metal interface, thereby minimizing surface recombination and contact resistance.
  17. 17 . The method of claim 13 , comprising a further step of removing deposited metal on an un-etched p-doped surface to improve light extraction.
  18. 18 . The method of claim 13 , comprising a further step of depositing an intermediate layer before depositing the noble metal to finely tune resonance energy of a plasmonic nanoparticle.
  19. 19 . The method of claim 13 , comprising a further step of depositing a passivation layer at a noble metal/semiconductor interface to reduce surface recombination velocity.
  20. 20 . The method of claim 13 , comprising a further step of partially filling the etched features with the noble metal for enhanced plasmonic effect.

Description

FIELD Aspects of the disclosure relate to methods for manufacturing semiconductor devices for high-speed communication. BACKGROUND Group III nitrides are compounds formed by nitrogen and one or more Group III elements from the periodic table, such as aluminum (Al), gallium (Ga), and indium (In). These materials have attracted substantial attention in optoelectronics, particularly for use in portable consumer devices like handheld projectors, high-resolution televisions, displays, lighting systems, and high-speed communication technologies. Among the Group III nitride materials, micro-LEDs are especially valued for their compatibility with a wide range of portable consumer devices, such as handheld projectors, high-resolution televisions, displays, lighting solutions, and high-speed communication systems. The lower thermal resistance of micro-LEDs allows for operation at higher current densities. Since power consumption according to P=I2R, scales quadratically with I, increase in resistance at smaller LED sizes does not dominate the lower current requirements. Thus higher current densities with lower power consumption leads to greater 3 dB bandwidth and improved emission efficiency. Furthermore, their compact size enables the integration of micro-LED arrays, which significantly boosts system throughput. However, significant challenges remain in the fabrication of GaN-based micro-LEDs, including high material defect densities (around 109 defects per cm2) and strong intrinsic polarization fields (in the megavolt-per-centimeter range), both of which lead to efficiency losses at a wide range of current densities. GaN epitaxy is typically grown on substrates with considerable lattice mismatch, such as sapphire, silicon, or silicon carbide (SiC), which may result in misalignment and asymmetry between the substrate and GaN layer, and increases the incidence of material defects. In addition, polarization is an inherent, non-centrosymmetric property of GaN crystals. In the typical <0001> growth direction, wurtzite (hexagonal) phase GaN displays distinct polarity, which negatively impacts LED recombination characteristics by causing inefficient recombination between misaligned electron and hole wavefunctions. Recently, significant efforts have focused on improving the emission efficiency of InGaN/GaN multiple quantum wells (MQWs) by coupling them with surface plasmons (SPs). In 1999, Gontijo et al. predicted that when surface plasmons (SPs) are resonantly excited in metal nanostructures, the spontaneous emission rate (SER) of the emitter could be enhanced by over 1000 times, with the resulting evanescent field influencing the emitter [1]. When a metal layer is placed near a quantum well (QW) and the bandgap energy of the quantum well is close to the energy of the SPs, energy can be transferred to the SPs at the metal interface, creating surface plasmon polaritons (SPPs) or localized surface plasmon (LSP). This energy transfer increases electron-hole recombination rates and enhances spontaneous emission, improving internal quantum efficiency (IQE) and extraction efficiency and speeding up carrier dynamics. To emit light from SPPs, momentum matching is required, which can be achieved by texturing the metal layer through diffraction gratings or rough surfaces. A recent demonstration of a light-emitting hyperbolic metasurface, utilizing nanostructured silver (Ag) and indium gallium arsenide phosphide (InGaAsP) quantum wells, highlights the potential of III-V compound semiconductors as promising candidates for developing LEDs that are both efficient and fast. Several studies have reported improved emission efficiency of InGaN/GaN multiple quantum wells (MQWs) in the blue-light spectral region through quantum well-surface plasmon (QW-SP) coupling. Okamoto et al. demonstrated a 14-fold increase in blue emission using bottom excitation and detection from a silver (Ag)-coated sample with a 10-nm GaN spacer layer between the InGaN QWs and the silver layer [2]. Furthermore, the anisotropic polarization response of the metasurface can enhance the transmission rate of LEDs used in visible light communication (VLC) by providing an additional degree of freedom using light polarization for encoding information. However, these designs are impractical for devices due to poor p-doping and light-blocking effects. Kwon et al. embedded Ag particles near the n-GaN/MQW interface for improved device operation, however, there were challenges such as process interruptions, impurity risks, and poor crystal quality [3]. J. Henson's work with silver nanocylinder arrays showed near-green light enhancement but also required a thin spacer layer for efficient SP coupling, making it less feasible for practical devices [4]. Overall, while SP coupling shows potential for improving LED efficiency, numerous challenges remain for practical implementation, including reliability and radiative efficiency issues. Currently, the total light output power from the