We demonstrate a high-speed nonpolar m-plane InGaN/GaN micro-scale light-emitting diode (LED) with record electrical -3 dB modulation bandwidth of 1.5 GHz at current density 1 kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . A differential carrier lifetime (DLT) 200 ps was extracted using rate-equation model. The short DLT is attributed to the high electron-hole wave function overlap in polarization-free quantum wells, which leads...

Free-standing nonpolar GaN substrates provide an excellent platform for the fabrication of high-speed blue and green light-emitting diodes (LEDs), which are attractive visible-light communication, plastic optical fiber short-range under water communication. Nonpolar LEDs on free-standing exhibit a large electron-hole wave function overlap, low extended defect density, favorable thermal properties. Here, we demonstrate InGaN/GaN with peak emission wavelength between 455 465 nm substrates. A...

High-speed InGaN/GaN blue light-emitting diodes (LEDs) are needed for future gigabit-per-second visible-light communication systems. Large LED modulation bandwidths typically achieved at high current densities, with reports close to 1 GHz bandwidth densities ranging from 5 10 kA/cm2. However, the internal quantum efficiency (IQE) of LEDs is quite low due well-known droop phenomenon. Here, we show experimentally that nonpolar and semipolar orientations GaN enable higher where IQE expected be...

We present the first demonstration of RF characteristics electrically injected GaN/InGaN core–shell nanowire-based micro light-emitting diodes (μLEDs) for μLED displays and visible-light communication. A record −3 dB modulation bandwidth ∼1.2 GHz at 1 kA/cm2 (higher than any LED grown on c-plane GaN), a low-leakage current–voltage characteristic with excellent rectifying behavior are achieved. Analysis using small-signal equivalent electrical circuit μLEDs indicates significantly longer...

This work describes a small-signal microwave method for determining the differential carrier lifetime and transport effects in electrically injected InGaN/GaN light-emitting diodes (LEDs). By considering diffusion, capture, thermionic escape, recombination, rate equations are used to derive an equivalent electrical circuit LEDs, from which expressions input impedance modulation response obtained. The simultaneously fit experimental data nonpolar micro-LEDs on free-standing GaN substrates....

The yellow luminescence band was studied in undoped and Si-doped GaN samples by steady-state time-resolved photoluminescence. At low temperature (18 K), the zero-phonon line (ZPL) for is observed at 2.57 eV attributed to electron transitions from a shallow donor deep-level defect. higher temperatures, ZPL 2.59 emerges, which conduction same In addition ZPL, set of phonon replicas observed, caused emission phonons with energies 39.5 meV 91.5 meV. defect called YL1 center. possible identity...

We demonstrate the first electrically injected nonpolar m-plane GaN-based vertical-cavity surface-emitting lasers (VCSELs) with lattice-matched nanoporous bottom DBRs. Lasing under pulsed operation at room temperature was observed near 409 nm a linewidth of ∼0.6 and maximum output power ∼1.5 mW. The VCSELs were linearly polarized polarization-locked in a-direction, polarization ratio 0.94. high pinning reveal that optical scattering from DBRs is negligible. A characteristic 357 K resulted...

We theoretically and experimentally investigate Tamm plasmon (TP) modes in a metal/semiconductor distributed Bragg reflector (DBR) interface. A thin Ag (silver) layer with thickness (55 nm from simulation) that is optimized to guarantee low reflectivity at the resonance was deposited on nanoporous GaN DBRs fabricated using electrochemical (EC) etching freestanding semipolar (20 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mover> <mml:mn>21</mml:mn> <mml:mo...

We observed varying thermal quenching behavior of the yellow luminescence band near 2.2 eV in different GaN samples. In spite behavior, all samples is caused by same defect—the YL1 center. conductive n-type GaN, quenches with exponential law, and Arrhenius plot reveals an ionization energy ∼0.9 for semi-insulating abrupt tunable observed, where apparent activation not related to defect. this case, can be found analyzing shift characteristic temperature PL excitation intensity. conclude that...

We report the fabrication of m-plane nanoporous distributed Bragg reflectors (DBRs) on free-standing GaN substrates. The DBRs consist 15 pairs alternating undoped and highly doped n-type ([Si] = ∼3.7 × 1019 cm−3) GaN. Electrochemical (EC) etching was performed to convert regions into a porous material, consequently reducing effective refractive index layers. demonstrate DBR with peak reflectance greater than 98% at 450 nm stopband width ∼72 nm. polarization ratio an incident polarized light...

Diffusion lengths of photo-excited carriers along the c-direction were determined from photoluminescence (PL) and cross-sectional cathodoluminescence (CL) measurements in p- n-type GaN epitaxial layers grown on c-plane sapphire by metal-organic chemical vapor deposition. The investigated samples incorporate a 6 nm thick In0.15Ga0.85N active layer capped with either 500 p-GaN or 1500 n-GaN. top etched steps PL InGaN region underlying was monitored as function thickness upon photo-generation...

We report the carrier dynamics and recombination coefficients in single-quantum-well semipolar (202 ̅ 1 ) InGaN/GaN light-emitting diodes emitting at 440 nm with 93% peak internal quantum efficiency.The differential lifetime is analyzed for various injection current densities from 5 A/cm 2 to 10 kA/cm , corresponding are obtained.The coupling of efficiency vs injected density (n) enables separation radiative nonradiative lifetimes extraction Shockley-Read-Hall (SRH) (), Auger () their n-dependency

InGaN/GaN light-emitting diodes (LEDs) with large modulation bandwidths are desirable for visible-light communication. Along speed, the consideration of internal quantum efficiency (IQE) under operating conditions is also important. Here, we report characteristics semipolar (202¯1¯) single-quantum well (SQW) and multiple-quantum-well (MQW) active regions grown on free-standing GaN substrates peak efficiencies (IQEs) 0.93 0.73, respectively. The MQW LEDs exhibit average about 40–80% higher...

We report high-voltage regrown nonpolar m-plane p-n diodes on freestanding GaN substrates. A high blocking voltage of 540 V at ~1 mA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (corresponding to an electric field E ~ 3.35 MV/cm), turn-ON voltages between 2.9 and 3.1 V, specific on-resistance 1.7 mΩ·cm 300 A/cm , a minimum ideality factor were obtained for the diodes. Our results suggest that Si, O, C interfacial impurity levels up...

Abstract Multiphysics processes such as recombination dynamics in the active region, carrier injection and transport, internal heating may contribute to thermal efficiency droop InGaN/GaN light-emitting diodes (LEDs). However, an unambiguous methodology characterization technique decouple these under electrical determine their individual roles phenomena is lacking. In this work, we investigate electrically injected single-quantum-well LEDs by decoupling inherent radiative efficiency, effects...

We report on the polarity control of ZnO grown by plasma assisted molecular beam epitaxy Ga polar (0001) GaN/sapphire templates simply via oxygen‐to‐Zn (VI/II) ratio during growth a thin nucleation layer at 300 °C. Following Zn pre‐exposure, layers nucleated with low VI/II ratios (&lt;1.5) exhibited Zn‐polarity. Those above 1.5, O‐polarity. Supported scanning transmission electron microscopic imaging, we have unequivocally demonstrated that inversion takes place without formation any...

We report on the vertical hole transport through unipolar unintentionally doped (UID) and p-type AlGaN heterostructures to evaluate effectiveness of UID as barriers transport. Band diagram current density–voltage (J–V) simulations are conducted in one-dimensional three-dimensional schemes, with latter including compositional fluctuations within alloy barrier layer. The simulation results using a self-consistent Poisson-drift diffusion scheme, incorporating Localization Landscape theory,...

Optical properties of GaN/Al0.2Ga0.8N multiple quantum wells grown with semi-polar (10-11) orientation on patterned 7°-off Si (001) substrates have been investigated. Studies performed at 8 K reveal the in-plane anisotropic behavior QW photoluminescence (PL) intensity for this orientation. The time resolved PL measurements were carried out in temperature range from to 295 deduce effective recombination decay times, respective radiative and non-radiative contributions. component remains...

We demonstrate a superluminescent diode fabricated on nonpolar m-plane GaN substrate by employing linearly tapered waveguide design. A high electrical -3dB modulation bandwidth ( f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3dB</sub> ) of 2.5 GHz at current density 30 kA/cm <sup xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is achieved. The attributed to the shorter carrier recombination lifetime, linear gain curve in quantum wells,...

The effect of δ-doping In0.06Ga0.94N barriers with Mg on the quantum efficiency blue light-emitting-diodes (LEDs) active regions composed 6 (hex) 3-nm In0.15Ga0.85N is investigated. Compared to reference sample, first barrier n-side LED structure improves peak external (EQE) by 20%, owing increased hole concentration in wells adjacent n-side, as confirmed numerical simulations carrier distributions across region. Doping second barrier, addition one, did not further enhance EQE, which likely...

A nonpolar GaN-based vertical-cavity surface-emitting laser (VCSEL) using nanoporous bottom epitaxial distributed Bragg reflector (DBR) is demonstrated at room temperature (RT) under continuous-wave (CW) optical pumping. The porous layers enable the growth of lattice-matched high-reflectance DBRs without sacrificing conductive properties needed for high-performance VCSELs. 2-λ cavity VCSEL reported here employs a hybrid design with top dielectric DBR and DBR. Single longitudinal mode lasing...

Impacts of silicon, carbon, and oxygen interfacial impurities on the performance high‐voltage vertical GaN‐based p–n diodes are investigated. The results indicate that moderate levels (≈5 × 10 17 cm −3 ) all lead to reverse blocking voltages ( V b greater than 200 at 1 μA −2 forward leakage less nA 1.7 V. At higher impurity levels, becomes compromised. Herein, it is concluded each has a different effect device performance. For example, high carbon spike junction correlates with off‐state...

Among the major obstacles for development of non-polar and semipolar GaN structures on foreign substrates are stacking faults which deteriorate structural optical quality material. In this work, an in-situ SiNx nano-network has been employed to achieve high heteroepitaxial (112¯2) m-plane sapphire with reduced fault density. This approach involves deposition a porous interlayer that serves as nano-mask subsequent growth, starts in nanometer-sized pores (window regions) then progresses...

We extract the injection efficiency as a function of current density in single-quantum-well semipolar (202¯1¯) InGaN/GaN light-emitting diodes (LEDs) using small-signal RF measurements and rate equation analysis dominant carrier mechanisms. The equations are used to derive equivalent circuit that yields expressions for modulation response input impedance LED. Simultaneous fitting measured LED gives differential lifetime, net escape time from active region, recombination lifetime cladding...