About

Shuji Nakamura is a professor in the Materials Department at the University of California, Santa Barbara. He is widely recognized as a pioneer in light emitters based on wide-bandgap semiconductors and has made significant advancements in the development of GaN thin film technology for high-efficiency Nitride-based LEDs and laser diodes. Nakamura's research focuses on electronic and photonic materials, and he has received numerous honors including the Nobel Prize in Physics, the Global Energy Prize, the Zayed Future Energy Prize, the Harvey Prize for advancements in Science and Technology, the Benjamin Franklin Medal in Engineering, and the Millennium Technology Prize. He holds the title of CREE Professor of Solid State Lighting and Displays and is affiliated with the Materials faculty at UC Santa Barbara.

Research topics

• Materials science
• Optoelectronics
• Optics
• Physics
• Nanotechnology
• Chemistry
• Atomic physics

Selected publications

• Probing In-Solid Proton Energy Distributions in Laser-Driven Fusion via Nuclear Activation Diagnostics

  ArXiv.org · 2026-05-09

  articleOpen access

  The energy distribution of energetic protons inside a solid target is a key quantity governing nuclear reaction yields and energy deposition in high-intensity laser-driven fusion, including nonthermal proton--boron (p--B) schemes and proton fast ignition. Yet it has remained inaccessible to conventional particle diagnostics, which detect only ions escaping the target and are perturbed by intense plasma electromagnetic fields. Here we establish a quantitative diagnostic that uses nuclear activation reactions occurring within the target itself as an internal probe of the in-solid proton energy distribution. Applied to laser-driven p--B fusion experiments on the kJ-class laser, the method reconstructs an exponential-equivalent in-solid proton energy distribution from the absolute yields of $^{11}\mathrm{C}$ and $^{7}\mathrm{Be}$ produced via $\mathrm{^{11}B(p,n)^{11}C}$ and $\mathrm{^{10}B(p,α)^{7}Be}$, and yields the absolute number of $\mathrm{^{11}B(p,2α)^{4}He}$ reactions through a side-channel analysis with propagated cross-section uncertainties. This work opens a quantitative window onto the in-solid proton dynamics that drive nuclear reactions in laser-driven fusion experiments.

  PublisherOA PDF

• Probing In-Solid Proton Energy Distributions in Laser-Driven Fusion via Nuclear Activation Diagnostics

  arXiv (Cornell University) · 2026-05-09

  preprintOpen access

  The energy distribution of energetic protons inside a solid target is a key quantity governing nuclear reaction yields and energy deposition in high-intensity laser-driven fusion, including nonthermal proton--boron (p--B) schemes and proton fast ignition. Yet it has remained inaccessible to conventional particle diagnostics, which detect only ions escaping the target and are perturbed by intense plasma electromagnetic fields. Here we establish a quantitative diagnostic that uses nuclear activation reactions occurring within the target itself as an internal probe of the in-solid proton energy distribution. Applied to laser-driven p--B fusion experiments on the kJ-class laser, the method reconstructs an exponential-equivalent in-solid proton energy distribution from the absolute yields of $^{11}\mathrm{C}$ and $^{7}\mathrm{Be}$ produced via $\mathrm{^{11}B(p,n)^{11}C}$ and $\mathrm{^{10}B(p,α)^{7}Be}$, and yields the absolute number of $\mathrm{^{11}B(p,2α)^{4}He}$ reactions through a side-channel analysis with propagated cross-section uncertainties. This work opens a quantitative window onto the in-solid proton dynamics that drive nuclear reactions in laser-driven fusion experiments.

  PublisherDOI

• Developments toward monolithic III-N microLEDs: red InGaN active region and tunnel junctions grown by MOCVD

  2025-03-19

  article
  PublisherDOI

• Enhanced emission efficiency and directionality in InGaN/GaN microLEDs laterally enclosed by distributed Bragg reflectors

  Optics Express · 2025-12-19 · 2 citations

  articleOpen access

  Enhancing the efficiency and beam directivity of GaN micron-scale light-emitting diodes (µLEDs) is critical for visible-light communication, which has emerged as a promising platform for high-bandwidth optical links in data-center environments. We demonstrate a µLED design where the emitting mesa is laterally enclosed by a distributed Bragg reflector (DBR). This design achieves ∼20% higher optical output through air-side emission and ∼130% higher optical output through substrate-side emission with ∼30% reduced divergence compared to reference devices enclosed by a TiO 2 film. Our results present a manufacturable route to efficient, directional µLEDs with applications in optical interconnects and advanced display technologies.

  PublisherDOI

• Gallium Nitride and Related Materials

  ˜The œMaterials Research Society series · 2025-01-01 · 162 citations

  bookOpen access
  PublisherOA PDFDOI

• 10.4% external quantum efficiency 294 nm UV LEDs at 20 A/cm² with a fully transparent tunnel junction

  Optics Express · 2025-04-16 · 1 citations

  articleOpen access

  We report on the successful demonstration of an all metalorganic chemical vapor deposition (MOCVD) grown fully transparent tunnel junction (TJ) germicidal UV LED, resulting from the use of a lightly doped n - -AlGaN contact layer enabling rapid MOCVD growth optimization. We found that the optimal condition for LED performance was a 3 nm p ++ -Al 0.6 Ga 0.4 N / 9 nm n ++ -Al 0.65 Ga 0.35 N TJ above a 20 period 1 nm p-Al 0.8 Ga 0.2 N/ 1 nm p-Al 0.2 Ga 0.8 N short-period superlattice (SPSL). We observed a peak external quantum efficiency (EQE) of the λ = 294 nm TJ UV LED of 12.1%, and an EQE of 10.4% at 20 A/cm 2 and 9.1% at 35 A/cm 2 , with an excess voltage of 1.5 V at 1 A/cm 2 .

  PublisherDOI

• Laser-based inertial fusion energy system enabled by optical enhancement cavities and a direct-drive configuration reactor

  Optics Express · 2025-10-20 · 1 citations

  articleOpen accessSenior author

  We propose a novel and highly efficient laser inertial fusion energy reactor concept based on the shock ignition scheme, in which laser-plasma instabilities are mitigated through 500-beam, multicolor, slowly rotating polarization laser beam irradiation. The system employs coherent beam-combined fiber lasers injected into high-finesse optical enhancement cavities, which have already demonstrated energy enhancement factors approaching 60,000 and are expected to surpass 100,000. The 1.06 μ m laser output is frequency-tripled to 0.35 μ m ultraviolet light, resulting in an overall wall-plug-to-ultraviolet-light efficiency of approximately 10%. The reactor integrates a helium-gas-cooled lead-lithium blanket and a direct energy conversion for high-efficiency operation. It is designed for cryogenic deuterium-tritium targets in a direct drive scheme at 1–10 Hz, repetition rate, providing net electric output at 0.1–2.8 GW. This approach offers a compact, scalable, and credible pathway toward practical commercial laser fusion energy.

  PublisherDOI

• A Fabrication Method for Lifting off Wafer-Scale III-Nitride Materials with Smooth Lift-off Interfaces

  2025-01-01

  articleSenior author

  Wafer-scale III-nitride epitaxial layers are selectively lifted off via an innovative electrochemical etching method, allowing epilayers to achieve ultra-high relaxation, preserved quality, and sub-nanometer root-mean-square interface roughness for diverse applications, as demonstrated with micro-light-emitting diodes.

  PublisherDOI

• Unexpected origin of the quantum efficiency reduction in long-wavelength <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mo stretchy="false">(</mml:mo><mml:mi>In</mml:mi><mml:mo>,</mml:mo><mml:mi>Ga</mml:mi><mml:mo stretchy="false">)</mml:mo><mml:mrow><mml:mrow><mml:mi mathvariant="normal">N</mml:mi></mml:mrow></mml:mrow></mml:math> light-emitting diodes

  Physical Review Applied · 2025-03-03 · 6 citations

  article

  Differential carrier lifetime (DCL) measurements were performed on c-plane ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{N}/\mathrm{Ga}\mathrm{N}$ single-quantum-well (QW) light-emitting diodes (LEDs) with varying indium-content QWs (x = 13.5%, 16%, 22%), emitting with violet, blue, and green wavelengths. The recombination lifetimes of LEDs were found to increase with increasing indium composition, resulting in increased carrier densities n measured by DCL. Extraction of the A coefficients, which are assumed to not vary with n, and of the effective B(n) and C(n) coefficients of the ABC model of the internal quantum efficiency (IQE) of QWs showed no significant changes in the A coefficient with increasing indium content [$\mathrm{In}$] in the ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{N}$ QW, and a reduction in the B(n) and C(n) coefficients with increasing [$\mathrm{In}$]. When looking at the Shockley-Read-Hall (SRH) recombination rate An, the radiative recombination rate B(n)${n}^{2}$, and the Auger-Meitner (AM) recombination rate C(n)${n}^{3}$, we observed that at any given n, the SRH rate is the same for the three [$\mathrm{In}$] measured, while the radiative rate decreases (by up to approximately 9 times) and the AM rate decreases (by up to approximately 7 times) with increasing indium content. This shows that the larger reduction in radiative recombination rates relative to nonradiative recombination rates with increasing [$\mathrm{In}$] is the largest contributor to the decreased quantum efficiencies of LEDs (the ``green gap'') at any given n. While some of the reduction in the effective recombination coefficients B(n) and C(n) can be explained by the reduced wave-function overlaps of the QW with increasing indium content, the larger reduction of B(n) relative to C(n) motivates further study of the intrinsic recombination coefficients ${B}_{0}$ and ${C}_{0}$ of bulk ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{N}$ alloys and how they are related to the effective recombination coefficients B(n) and C(n) in QWs. The relative contributions of nonradiative recombination are enhanced at any given current density due to the sublinear relationship between the carrier density n and the current density. Thus, the solution to the green gap, up to any intrinsic limitations set by the indium content of the QW, from an IQE perspective, requires the design of long-wavelength $(\mathrm{In},\mathrm{Ga})\mathrm{N}$ LEDs with improved wave-function overlaps that can operate with a lower carrier density at any given current density.

  PublisherDOI

• III-nitride thin film liftoff using electrochemical etching

  Applied Physics Letters · 2025-09-08 · 3 citations

  articleSenior author

  We report a selective electrochemical etching-based liftoff technique for III-nitride thin films using a heavily Si-doped sacrificial layer. This method enables the detachment of the millimeter-sized III-nitride thin films with tunable thickness from arbitrary substrates, achieving minimal damage and sub-nanometer liftoff surface roughness, offering more flexibility than traditional liftoff methods such as laser liftoff. Structure and optical characterization confirm the preservation of the crystal quality throughout the process. Notably, InGaN-based blue μLEDs were lifted off and transferred onto Si substrates, maintaining excellent optoelectronic properties, showing great potential in mass transfer of nitride-based μLEDs for micro-display. This proof-of-concept demonstration highlights a scalable, low-damage pathway for heterogeneous integration of III-nitride materials onto diverse platforms for advanced optoelectronic applications.

  PublisherDOI

Frequent coauthors

• Steven P. DenBaars

  743 shared

• James S. Speck

  University of California, Santa Barbara

  571 shared

• Shigefusa F. Chichibu

  Tohoku University

  143 shared

• Claude Weisbuch

  École Polytechnique

  127 shared

• Feng Wu

  University of California, Santa Barbara

  123 shared

• S. Keller

  University of California, Santa Barbara

  113 shared

• Umesh K. Mishra

  98 shared

• Kenji Fujito

  Mitsubishi Chemical (Japan)

  77 shared

Awards & honors

• Nobel Prize in Physics
• NAE
• NAI
• NIHF
• Royal Academy of Engineering CREE Professor of Solid State L…