A5004768636- GaN-based semiconductor devices and materials
- Semiconductor Quantum Structures and Devices
- ZnO doping and properties
- Ga2O3 and related materials
- Metal and Thin Film Mechanics
- Semiconductor materials and devices
- Semiconductor Lasers and Optical Devices
- Acoustic Wave Resonator Technologies
- Gas Sensing Nanomaterials and Sensors
- Spectroscopy and Laser Applications
- Carbon Nanotubes in Composites
- Neuroscience and Neural Engineering
- Advanced Fiber Laser Technologies
- Graphene research and applications
- Optical Coatings and Gratings
- Photocathodes and Microchannel Plates
University of California, Santa Barbara
2019-2023
University of California, Davis
2011
AP Photonics (China)
2006
Red LEDs were grown by metalorganic chemical vapor deposition with a high active region temperature of 870 °C on relaxed InGaN/GaN superlattice buffer. The buffer was 100% biaxially the thermal decomposition an InGaN underlayer, measured resolution X-ray diffraction. Fabricated showed low forward voltage 2.25 V at current density 25 Acm−2 no Al-containing layers in region, peak emission wavelength 633 nm 200 and on-wafer external quantum efficiency 0.05%. Uniform red relaxation observed...
A highly relaxed InGaN buffer layer was demonstrated over a full two-inch c-plane sapphire substrate by metalorganic chemical vapor deposition. The grown on 100 nm GaN decomposition stop with 3 thick high indium composition underlayer. After thermal of the underlayer at 1000 °C, 200 In0.04Ga0.96N showed 85% biaxial relaxation measured resolution x-ray diffraction reciprocal space map. When used as pseudo-substrate for regrowth InGaN/InGaN multi-quantum wells, sample 75 red-shift in room...
InGaN-based red micro-size light-emitting diodes (μLEDs) have become very attractive. Compared to common AlInGaP-based µLEDs, the external quantum efficiency (EQE) of InGaN µLEDs has less influence from size effect. Moreover, exhibit a much more robust device performance even operating at high temperature up 400 K. We review progress μLEDs. Novel growth methods relax strain and increase wells are discussed.
A novel approach to realize DFB gratings on GaN based laser diodes is presented and continuous-wave single longitudinal mode operation achieved. The first order were fabricated the surface of indium tin oxide (ITO) top ridge, which combines benefits simplified fabrication, easy scalability wider ridges, no regrowth or overgrowth. Under operation, emits with a full FWHM 5 pm, SMSR 29 dB output power from facet as high 80 mW. To best authors' knowledge, this also demonstration DFB-LD semipolar...
Red‐emitting (≈643 nm) InGaN multiquantum well active device layers and micro‐LEDs are grown by metal organic chemical vapor deposition (MOCVD) on relaxed templates, the latter created via thermal decomposition of an underlayer, examined power‐ temperature‐dependent photoluminescence electrical measurements. Maximum internal quantum efficiencies determined to be 7.5% at excitation power density 13 W cm −2 , radiative recombination occurs through monomolecular recombination, fabricated do not...
In this study, III-nitride red micro-light-emitting diodes (µLEDs) with ultralow forward voltage are demonstrated on a strain relaxed template. The ranges between 2.00 V and 2.05 at 20 A/cm2 for device dimensions from 5 × to 100 µm2. µLEDs emit 692 nm 637 A/cm2, corresponding blueshift of 55 due the screening internal electric field in quantum wells. maximum external efficiency wall-plug 0.31% 0.21%, respectively. This suggests that efficient can be realized further material optimizations.
A III-nitride red LED with an active region temperature of 835 °C on a Si substrate utilizing strain-relaxed template (SRT) is demonstrated. The peak wavelength blueshifts from 670 nm at 1 A/cm2 to 636 150 A/cm2. on-wafer external quantum efficiency was 0.021% 7 emission 655 nm. grown exhibited 116 redshift when compared co-loaded sapphire. This attributed the difference in strain state for layers sapphire, allowing more indium be incorporated Si. suggests efficient LEDs and µLEDs SRT can...
The electrical performances of III-nitride blue micro-light-emitting diodes (µLEDs) with different tunnel junction (TJ) epitaxial architectures grown by metalorganic chemical vapor deposition are investigated. A new TJ structure that employs AlGaN is introduced. current density–voltage characteristic improved incorporating layer above the n-side layer, and effects AlGaN/GaN superlattices examined. Based upon data from band diagram simulation, net positive polarization charge formed at...
Electrically driven c-plane InGaN-based blue edge emitting laser diodes on a strain-relaxed template (SRT) are successfully demonstrated. The relaxation degree of the InGaN buffer was 26.6%, and root mean square (RMS) roughness surface morphology 0.65 nm. (LDs) SRT at 459 nm had threshold current density 52 kA/cm2 under room temperature pulsed operation. internal loss LDs 30–35 cm−1. Regardless high density, this is first demonstrated diode using method GaN.
The optical and electrical characteristics of InGaN blue green micro-light-emitting diodes (μLEDs) with GaN tunnel junction (TJ) contacts grown by metalorganic chemical vapor deposition (MOCVD) were compared at different activation temperatures among three methods from the literature, namely, sidewall activation, selective area growth (SAG), treatment before activation. devices resulted in uniform electroluminescence higher light output power, to SAG. Moreover, μLEDs showed greater...
Single-frequency blue laser sources are of interest for an increasing number emerging applications but still difficult to implement and expensive fabricate suffer from poor robustness. Here a novel universal grating design realize distributed optical feedback in visible semiconductor diodes (LDs) was demonstrated on semipolar InGaN LD, its unique effect the performance investigated. For first time, best our knowledge, low threshold voltage, record-high power output, ultra-narrow single-mode...
As the Feature size of interconnect technology continues to scale down nanometer sizes, state-of-the-art Cu is expected run into its physical limit in near future. Carrier scattering at surfaces and grain boundaries leads a dramatic increase resistivity nanoscale, resulting increasing resistance–capacitance signal delay [1].
A novel approach to realize DFB gratings on GaN based laser diodes is presented and single longitudinal mode operation achieved. For lasers with plasma-etched surface gratings, was maintained until 900 mA the spectral width FWHM less than 5 pm a SMSR of more 29 dB. Moreover, several issues limiting performance semipolar III-Nitride etched grating are also addressed in this work. Besides these first order that were formed by electron beam lithography shallow plasma etching, an improved design...
InGaN based c-plane blue LDs on strain relaxed template (SRT) with a reduced absorption loss was demonstrated. The is from 27 cm−1 to 20 cm−1. Due the lower loss, threshold current density improved 51.1 kA/cm2 43.7 kA/cm2, and slope efficiency also increased by factor of 1.22. decomposition layer (DL) in SRT confirmed be major extra source both experimental simulation results. With higher indium content buffer waveguide layers, optical leakage into DL can suppressed.
We discuss the use of GaN high-power laser diode in general lighting applications. After reviewing achievements; phosphors materials, optical design and possible performances these devices are discussed.