Steven P. DenBaars
· NAE, NAI Mitsubishi Professor of Solid State Lighting and Displays, Materials Distinguished Professor, Electrical & Computer EngineeringVerifiedUniversity of California, Santa Barbara · Materials
Active 1986–2026
About
Steven P. DenBaars is a Mitsubishi Professor of Solid State Lighting and Displays and a Distinguished Professor in the Department of Electrical & Computer Engineering at the University of California, Santa Barbara. He is also the Co-Director of the Solid State Lighting & Energy Electronics Center and a Group Leader at the IEE. His research interests include the growth of wide-bandgap (GaN based) semiconductors and their application to blue LEDs, laser devices, and high power electronic devices. His work has led to the first U.S. university demonstration of a blue GaN laser diode. Dr. DenBaars has received numerous honors, including being named an IEEE Fellow, receiving the Aron Kressel Award from the IEEE Photonics Society, the Japanese Science of Applied Physics (JSAP) Outstanding Paper Award, the Viterbi Award, and the Distinguished Alumni Award from the University of Southern California. He holds a Ph.D. in Electrical Engineering from the University of Southern California, an M.S. in Materials Science from the same institution, and a B.S. in Materials and Metallurgical Engineering from the University of Arizona.
Research topics
- Materials science
- Optics
- Optoelectronics
- Physics
- Nanotechnology
- Atomic physics
- Chemistry
Selected publications
Meta-LEDs for directing arbitrarily-polarized spontaneous emission in 2D
2026-03-05
articleDouble-dielectric DBR blue VCSEL via electrochemical lift-off technology
2026-03-05
articleOptics Express · 2025-04-16 · 1 citations
articleOpen accessWe 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 .
III-nitride thin film liftoff using electrochemical etching
Applied Physics Letters · 2025-09-08 · 3 citations
articleWe 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.
Optics Express · 2025-12-19 · 2 citations
articleOpen accessSenior authorEnhancing 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.
Physical Review Applied · 2025-03-03 · 6 citations
articleDifferential 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.
Applied Physics Letters · 2025-05-19
articleOpen accessThe quantum efficiency of micro-light emitting diodes (micro-LEDs) is lower than that of large area LEDs. This efficiency reduction is typically attributed to the nonradiative Shockley–Read–Hall recombination at the surface defects and current leakage through the sidewall region without a clear distinction between these effects. In this work, we attempt to find out which of these phenomena is most critical for the reduced efficiency of micro-LEDs. This has been done by mapping electroluminescence (EL) and photoluminescence (PL) and measuring PL dynamics in blue GaN micro-LEDs fabricated by dry etching. It has been found that in the as-etched device, the EL intensity is much lower than in devices with KOH etching and atomic layer deposition of SiO2. This effect is especially pronounced close to the sidewalls. On the other hand, PL decay times are similar in as-etched and passivated devices, both in their center and at the sidewalls. This allows concluding that the main mechanism of the reduced efficiency of micro-LEDs fabricated by dry etching is the current leakage in the sidewall region and not the nonradiative recombination. The KOH etching has been found to be the most efficient means to eliminate the current leakage.
Recent Advancements in N-polar GaN HEMT Technology
Crystals · 2025-09-22 · 2 citations
articleOpen accessN-polar GaN HEMT technology has emerged as a disruptive technology that outperforms Ga-polar GaN HEMTs in terms of high-frequency power amplification capability. In this paper, the authors present a comprehensive review of the evolution of N-polar GaN HEMT technology from the perspective of crystal growth, dielectrics, and metals on N-polar GaN, transistor design, and performance. Specifically, the authors discuss the progress of the N-polar GaN HEMTs toward high-frequency, high-power, and high-efficiency applications with recent record-level performances, demonstrated by the authors, at mmWave frequencies.
2025-03-19
articleSenior author2025-03-19
articleSenior authorIII-Nitride distributed feedback (DFB) laser diodes offer an elegant chip-scale solution for single-frequency blue and green photon sources, but are challenging to fabricate due to the narrow Fabry-Pérot mode spacing, delicate p-contact layer, and lattice mismatch in the nitride material system. Here, we present MOCVD-grown InGaN-based DFBs fabricated with first- and third-order SiOx surface gratings embedded in the ITO p-cladding layer. We compare two fabrication methods: first using electron beam lithography of hydrogen silsesquioxane (HSQ), then a more cost-effective and scalable fabrication using holographic lithography. Blue DFBs exhibit single longitudinal mode behavior with 5 pm (resolution-limited) full-width at half maximum and 25 dB side mode suppression. We characterize the free-running frequency noise power spectral density of a 443 nm InGaN DFB with a first-order grating using a correlated delayed self-heterodyne frequency discriminator, yielding a free-running intrinsic linewidth of 685 kHz and a β-separation line integrated linewidth of 3.47 MHz.
Recent grants
Understanding Defects Generated by the Low Temperature Aqueous Synthesis of ZnO
NSF · $330k · 2009–2012
Frequent coauthors
- 760 shared
James S. Speck
University of California, Santa Barbara
- 743 shared
Shuji Nakamura
University of California, Santa Barbara
- 505 shared
S. Keller
University of California, Santa Barbara
- 492 shared
Umesh K. Mishra
- 129 shared
Feng Wu
University of California, Santa Barbara
- 124 shared
P. Fini
- 119 shared
U. K. Mishra
Institute of Science and Technology Austria
- 100 shared
Shigefusa F. Chichibu
Tohoku University
Education
- 1988
PhD, Electrical Engineering
University of Southern California
- 1986
MS, Materials Science
University of Southern California
- 1984
BS, Metallurgical Engineering
The University of Arizona
Awards & honors
- IEEE Fellow
- Aron Kressel Award, IEEE Photonics Society
- Japanese Science of Applied Physics (JSAP) Outstanding Paper…
- Viterbi Award, USC
- Distinguished Alumni Award, University of Southern Californi…
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