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Showing papers in "Applied Physics Express in 2013"


Journal ArticleDOI
TL;DR: In this article, the use of an n-type Ga2O3 thin film can greatly improve the performance of n-Ga2O/p-Cu2O heterojunction solar cells.
Abstract: High-efficiency heterojunction solar cells consisting of a nondoped Ga2O3 thin film as an n-type semiconductor layer and a p-type Cu2O sheet as the active layer as well as the substrate, prepared by thermally oxidizing a Cu sheet, are demonstrated. The use of an n-type Ga2O3 thin film can greatly improve the performance of n-Ga2O3/p-Cu2O heterojunction solar cells. The highest efficiency of 5.38% was obtained in an Al-doped ZnO/Ga2O3/Cu2O heterojunction solar cell fabricated with an n-Ga2O3 thin-film layer prepared at room temperature with a thickness of 75 nm by a pulsed laser deposition method.

258 citations


Journal ArticleDOI
TL;DR: In this paper, a donor doping technique for β-Ga2O3 by using Si-ion (Si+) implantation was developed, which achieved a high activation efficiency of above 60% after annealing in a nitrogen gas atmosphere at a relatively low temperature of 900-1000 °C.
Abstract: We developed a donor doping technique for β-Ga2O3 by using Si-ion (Si+) implantation. For the implanted Ga2O3 substrates with Si+=1×1019–5×1019 cm-3, a high activation efficiency of above 60% was obtained after annealing in a nitrogen gas atmosphere at a relatively low temperature of 900–1000 °C. Annealed Ti/Au electrodes fabricated on the implanted Ga2O3 layers showed ohmic behavior. The Ga2O3 with Si+=5×1019 cm-3 showed the lowest specific contact resistance and resistivity obtained in this work of 4.6×10-6 Ωcm2 and 1.4 mΩcm, respectively.

246 citations


Journal ArticleDOI
TL;DR: In this article, the authors achieved over 60 mW output power from pseudomorphic ultraviolet light-emitting diodes in continuous wave operation with die thinning and encapsulation.
Abstract: In this letter, the achievement of over 60 mW output power from pseudomorphic ultraviolet light-emitting diodes in continuous wave operation is reported. Die thinning and encapsulation improved the photon extraction efficiency to over 15%. Improved thermal management and a high characteristic temperature resulted in a low thermal rolloff up to 300 mA injection current with an output power of 67 mW, an external quantum efficiency (EQE) of 4.9%, and a wall plug efficiency (WPE) of 2.5% for a single-chip device emitting at 271 nm in continuous wave operation.

164 citations


Journal ArticleDOI
TL;DR: In this paper, the light extraction efficiency (LEE) in AlGaN deep-ultraviolet (DUV) light-emitting diodes (LEDs) is investigated using finite-difference time-domain simulations.
Abstract: Light extraction efficiency (LEE) in AlGaN deep-ultraviolet (DUV) light-emitting diodes (LEDs) is investigated using finite-difference time-domain simulations. For flip-chip and vertical LED structures, LEE is obtained to be <10% due to strong DUV light absorption in the p-GaN layer. In flip-chip LEDs, LEE of transverse-magnetic (TM) modes is found to be more than ten times smaller than that of transverse-electric (TE) modes, which explains the decreasing behavior of external quantum efficiency of DUV LEDs with decreasing wavelength. It is also found that vertical LED structures can have advantages over flip-chip structures for increasing LEE in the TM mode.

160 citations


Journal ArticleDOI
TL;DR: In this article, the thermoelectric properties of the carrier-doped chalcopyrite alloys, Cu1-xFe1+xS2 with x = 0.03 and 0.05, and Zn0.03Cu0.97FeS2, were investigated.
Abstract: The chalcopyrite CuFeS2 is a natural magnetic semiconductor, where Fe spins order antiferromagnetically at TN = 853 K. We investigate the thermoelectric properties of the carrier-doped chalcopyrite alloys, Cu1-xFe1+xS2 with x = 0.03 and 0.05, and Zn0.03Cu0.97FeS2. All systems showed characteristic behavior of n-type degenerate semiconductors. The large Seebeck coefficient with a high carrier-density indicates enhanced carrier mass of m* = 3–6m0, where m0 is the electron mass. Consequently, the thermoelectric power factor exceeds 1×10-3 W K-2 m-1 at 400 K. We propose that utilizing magnetic semiconductor can be a new effective strategy to obtain enhanced values of the power factor.

157 citations


Journal ArticleDOI
TL;DR: In this paper, a spin-torque oscillator (STO) was fabricated with a nanopillar-shaped magnetic tunnel junction with perpendicularly magnetized FeB free and in-plane magnetized CoFeB reference layers.
Abstract: We fabricated a spin-torque oscillator (STO) having a nanopillar-shaped magnetic tunnel junction with perpendicularly magnetized FeB free and in-plane magnetized CoFeB reference layers. The perpendicular magnetization of the FeB was stabilized by strong perpendicular magnetic anisotropy induced at both the MgO tunnel barrier/FeB and FeB/MgO cap interfaces. Under a perpendicular field (3 kOe), the STO exhibited a large emission power (0.55 µW), a high frequency (6.3 GHz) and a high Q factor (135) simultaneously, all of which are the largest to date among nanopillar-shaped STOs. The bias voltage dependence of the oscillation property was well explained by the macrospin model.

157 citations


Journal ArticleDOI
TL;DR: In this paper, high-efficiency InGaN light-emitting diodes (LEDs) in the "green gap" range were fabricated on c-face sapphire (0001) substrates.
Abstract: High-efficiency InGaN light-emitting diodes (LEDs) in the "green gap" range were fabricated on c-face sapphire (0001) substrates. Optical properties were enhanced by band engineering of active layers and optimization of growth conditions. Output power and external quantum efficiency of 11.0 mW and 24.7% for a 559 nm green-yellow LED and 4.7 mW and 13.3% for a 576 nm yellow LED with the injection current of 20 mA were achieved, respectively.

145 citations


Journal ArticleDOI
TL;DR: In this article, an effective codopant was used to enhance red persistent luminescence in Cr3+-doped ZnGa2O4 spinel. But the results suggest that Bi2O3 may play a critical role in stabilizing Cr 3+ in Zn Ga 2O4:Cr,Bi phosphors.
Abstract: Bi2O3 was proved to be an effective codopant to enhance red persistent luminescence in Cr3+-doped ZnGa2O4 spinel. The Cr–Bi-codoped ZnGa2O4 phosphors showed about 10 times higher persistent luminescence intensity than the Cr-singly-doped phosphors. The radiance (in mW sr-1m-2) of persistent luminescence in ZnGa2O4:Cr,Bi phosphors was comparable to that in commercialized SrAl2O4:Eu,Dy phosphors. Increases of Cr3+ absorption and photoluminescence were also observed in the Cr–Br-codoped ZnGa2O4 sample. The obtained results suggest that Bi2O3 may play a critical role in stabilizing Cr3+ in ZnGa2O4 spinel.

132 citations


Journal ArticleDOI
TL;DR: In this article, the authors have fabricated Cu2Sn1-xGexS3 thin-film solar cells by cosputtering deposition of Cu and Sn followed by sulfurization in S and GeS2 vapors.
Abstract: We have fabricated Cu2Sn1-xGexS3 thin-film solar cells by cosputtering deposition of Cu and Sn followed by sulfurization in S and GeS2 vapors. The conversion efficiency was significantly improved to be as high as 6.0% compared with the values of Cu2SnS3 solar cells similarly fabricated. Scanning electron microscopy observation revealed that alloying with Ge accelerated the grain growth during the sulfurization process, contributing to the improvement in the conversion efficiency. The bandgap energy of Cu2Sn0.83Ge0.17S3 was about 1.0 eV, which is suitable for bottom cells used in double-junction solar cells.

130 citations


Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate the monolithic integration of green and orange InGaN-based nanocolumn light-emitting diodes (LEDs) on a (0001) sapphire substrate.
Abstract: We demonstrate the monolithic integration of green and orange InGaN-based nanocolumn light-emitting diodes (LEDs). Four nanocolumn LED crystals (LEDs 1 to 4), which consisted of regularly arranged InGaN-based nanocolumns in a triangular lattice of 400 nm lattice constant, were grown on the same GaN template on a (0001) sapphire substrate, with designed nanocolumn diameters D of 150, 190, 230, and 270 nm for LEDs 1–4, respectively. LEDs 1 to 3 operated under DC current injection at room temperature, emitting at 544, 583, and 597 nm, respectively. This experiment paves the way for the monolithic integration of three-primary-color nanocolumn LEDs.

128 citations


Journal ArticleDOI
TL;DR: In this paper, a new type of thermopile consisting of two ferromagnetic materials with anomalous Nernst effects (ANEs) of opposite signs was proposed, where the combination of perpendicularly magnetized FePt and MnGa wires enhances the ANE voltage effectively.
Abstract: We propose a new-type of thermopile consisting of two ferromagnetic materials with anomalous Nernst effects (ANEs) of opposite signs. L10-FePt and L10-MnGa have been chosen as the materials because they show large ANEs with opposite signs. The combination of perpendicularly magnetized FePt and MnGa wires enhances the ANE voltage effectively. The ANE in in-plane magnetized FePt films induced by applying a perpendicular temperature difference shows no variation against the film thickness, which is a promising characteristic for thermoelectric applications because the internal resistance of the thermopile, which determines the extractable electric power, can be reduced by increasing the thickness of ferromagnetic wires.

Journal ArticleDOI
TL;DR: In this article, the reliability and output power of AlGaN-based deep-ultraviolet light-emitting diodes (DUV-LEDs) fabricated on AlN substrates prepared by hydride vapor phase epitaxy are reported.
Abstract: The reliability and output power of AlGaN-based deep-ultraviolet light-emitting diodes (DUV-LEDs) fabricated on AlN substrates prepared by hydride vapor phase epitaxy are reported. TEM analysis revealed that dislocation density in LED layers, except the p-GaN layer, was below 106 cm-2. DUV-LEDs emitting at 261 nm exhibited an output power of 10.8 mW at 150 mA. The lifetime of these LEDs was estimated to be over 10,000 h for cw operation at 50 mA. No significant acceleration of output power decay at higher operation currents was observed. The estimated lifetime at the operation current of 150 mA was over 5,000 h.

Journal ArticleDOI
TL;DR: In this paper, a method for continuously growing large-domain organic semiconductor crystals was developed to fabricate multi-array high-mobility organic transistors, which achieved a mobility of 5-10 cm2 V-1 s-1.
Abstract: A method for continuously growing large-domain organic semiconductor crystals is developed to fabricate multi-array high-mobility organic transistors. An organic semiconductor solution is held at the edge of a moving blade to grow a large-area crystalline thin film. The continuous evaporation of the solvent at around 100 °C, while the solution is supplied at the same rate, allows the organic crystals to grow steadily on the substrate to several inches in size. The performance of the arrays of field-effect transistors based on the large-domain crystal films is excellent, with mobility of 5–10 cm2 V-1 s-1.

Journal ArticleDOI
TL;DR: In this paper, a high-electron-mobility transistors (HEMTs) with a thin channel, a thin InAlAs barrier layer, and a very high gate stem structure have been fabricated and characterized.
Abstract: 60 nm InAs high-electron-mobility transistors (HEMTs) with a thin channel, a thin InAlAs barrier layer, and a very high gate stem structure have been fabricated and characterized. The thickness of the channel, as well as that of the InAlAs barrier layer, was reduced to 5 nm. A stem height of 250 nm with a Pt-buried gate was used in the device configuration to reduce the parasitics. A high DC transconductance of 2114 mS/mm and a current-gain cutoff frequency (fT) of 710 GHz were achieved at VDS=0.5 V.

Journal ArticleDOI
TL;DR: In this paper, single-phase α''-Fe16N2 nanoparticles were synthesized with high reproducibility in gram amounts for the first time and exhibited saturation magnetization (Ms) of 234 emu/g at 5 K and a magnetocrystalline anisotropy constant (Ku) of 9.6×106 erg/cm3.
Abstract: Single-phase α''-Fe16N2 nanoparticles have been synthesized with high reproducibility in gram amounts for the first time. The nanoparticles were obtained through the various kinds of successive procedure starting from the reduction of Fe-oxides, followed by nitriding in an atmosphere with very low moisture and oxygen contents of less than 1 ppm through the entire process. The single-phase α''-Fe16N2 nanoparticles exhibited saturation magnetization (Ms) of 234 emu/g at 5 K and a magnetocrystalline anisotropy constant (Ku) of 9.6×106 erg/cm3. These magnetic properties of this α''-Fe16N2 nanoparticles suggest that a new path for a possible candidate of the rare-earth-free permanent magnet material with a high Ms.

Journal ArticleDOI
TL;DR: In this paper, structural and electrochemical properties of thin film electrodes of cobalt hexacyanoferrate, NaxCo[Fe(CN)6]0.9H2O, against x.
Abstract: We investigated structural and electrochemical properties of thin film electrodes of cobalt hexacyanoferrate, NaxCo[Fe(CN)6]0.902.9H2O, against x. The compound exhibits a high capacity of 135 mAh/g and an average operating voltage of 3.6 V against Na, with a good cyclability. The discharge curve exhibits two plateaus at ≈3.8 and ≈3.4 V, which are ascribed to the reduction processes of Fe3+ and Co3+, respectively. The ex situ X-ray diffraction (XRD) profiles reveal the robust nature of the host framework against Na+ intercalation/deintercalation. Thus, cobalt hexacyanoferrate is a promising candidate for the cathode material of sodium-ion secondary battery (SIB).

Journal ArticleDOI
TL;DR: In this paper, electrical spin injection from a ferromagnet to a bilayer graphene (BLG) through a monolayer (ML) of single-crystal hexagonal boron nitride (h-BN) was demonstrated.
Abstract: We demonstrate electrical spin injection from a ferromagnet to a bilayer graphene (BLG) through a monolayer (ML) of single-crystal hexagonal boron nitride (h-BN). A Ni81Fe19/ML h-BN/BLG/h-BN structure is fabricated using a micromechanical cleavage and dry transfer technique. The transport properties across the ML h-BN layer exhibit tunnel barrier characteristics. Spin injection into BLG has been detected through non local magnetoresistance measurements.

Journal ArticleDOI
TL;DR: In this article, a diamond Schottky barrier diodes with a thick field plate has been developed, and the diamond VSBD with a 30 µm square (8.8×10-6 cm2) electrode shows specific on-resistance and blocking voltage, such as 29.3 mΩ cm2 (3.3 kΩ) and 842 V at room temperature, respectively.
Abstract: Vertical-structured diamond Schottky barrier diodes with a thick field plate have been developed. The diamond VSBD with a 30 µm square (8.8×10-6 cm2) Schottky electrode shows specific on-resistance and blocking voltage, such as 29.3 mΩ cm2 (3.3 kΩ) and 842 V at room temperature, respectively, however, the lower specific on-resistance with a constant blocking voltage such as 9.4 mΩ cm2 (1 kΩ) and 840 V, respectively, have been realized at 250 °C. As a result, Baliga's figure of merit (BVBD2/RonS) is improved from 24.1 to 75.3 MW/cm2. This value is the best in diamond diodes at present. The diamond VSBD with a 1,000 µm square (9.7×10-3 cm2) Schottky electrode shows high forward current and low on-resistance, such as more than 5 A and 10.2 mΩ cm2 (1.04 Ω), respectively, at 250 °C. The estimated parasitic resistance of the SBD is less than 0.04 Ω.

Journal ArticleDOI
TL;DR: In this article, a two-step post structure realized a reduction of series resistance of the RTD, and the oscillation frequency significantly increased with the feed point closer to the center of patch antenna at around 1 THz.
Abstract: Oscillations from 1.02 to 1.40 THz were observed at room temperature from resonant-tunneling-diode (RTD)-based oscillators with integrated patch antennas by improving the mesa structure and tuning the length of the antenna and the feed point location of the RTD. A two-step post structure realized a reduction of series resistance of the RTD, and the oscillation frequency significantly increased with the feed point closer to the center of patch antenna at around 1 THz. Experimental results agreed well with the analysis.

Journal ArticleDOI
TL;DR: In this article, a crack-free AlGaN/GaN high-electron-mobility transistors (HEMTs) are presented on a 200 mm Si substrate by metal-organic chemical vapor deposition (MOCVD).
Abstract: Crack-free AlGaN/GaN high-electron-mobility transistors (HEMTs) grown on a 200 mm Si substrate by metal–organic chemical vapor deposition (MOCVD) is presented. As grown epitaxial layers show good surface uniformity throughout the wafer. The AlGaN/GaN HEMT with the gate length of 1.5 µm exhibits a high drain current density of 856 mA/mm and a transconductance of 153 mS/mm. The 3.8-µm-thick device demonstrates a high breakdown voltage of 1.1 kV and a low specific on-resistance of 2.3 mΩ cm2 for the gate–drain spacing of 20 µm. The figure of merit of our device is calculated as 5.3×108 V2 Ω-1 cm-2.

Journal ArticleDOI
TL;DR: In this paper, a comparative study of sodiated vs lithiated bulk Si, including the effects of Li-Li and Na-Na interactions on dopant mobility, is presented, showing that finite ion concentrations may improve the battery charge/discharge rate.
Abstract: We present a comparative computational study of sodiated vs lithiated bulk Si, including the effects of Li–Li and Na–Na interactions on dopant mobility Both Na and Li prefer to act as interstitial defects located at the tetragonal sites of the Si matrix The migration barrier between tetragonal sites is 054 eV larger for Na than for Li, which is expected to result in a drastically lower diffusion rate The interdopant interactions reduce the barrier for Li and Na diffusion by 016 and 028 eV, respectively, providing ab initio evidence that finite ion concentrations may improve the battery charge/discharge rate

Journal ArticleDOI
TL;DR: In this paper, large hexagonal single-crystalline domains of single-layer graphene are epitaxially grown by ambient-pressure chemical vapor deposition over a thin Cu(111) film deposited on c-plane sapphire.
Abstract: Large hexagonal single-crystalline domains of single-layer graphene are epitaxially grown by ambient-pressure chemical vapor deposition over a thin Cu(111) film deposited on c-plane sapphire. The hexagonal graphene domains with a maximum size of 100 µm are oriented in the same direction due to the epitaxial growth. Reflecting high crystallinity, a clear band structure with the Dirac cone is observed by angle-resolved photoelectron spectroscopy (ARPES), and a high carrier mobility exceeding 4,000 cm2 V-1 s-1 is obtained on SiO2/Si at room temperature. Our epitaxial approach combined with large domain growth is expected to contribute to future electronic applications.

Journal ArticleDOI
TL;DR: In this article, a "sombrero-shaped" nano-contact for a spin torque oscillator based on magnetic tunnel junctions was proposed, which reduced the shunt current through the capping layer, and hence improved the magnetoresistance (MR) ratio to 46% compared with an MR ratio of 3% in conventional nano contact structures.
Abstract: We have developed a new type of nanocontact structure called a "sombrero-shaped" nano-contact for a spin torque oscillator (STO) based on magnetic tunnel junctions. This structure reduces the shunt current, which passes through the capping layer, and hence improves the magnetoresistance (MR) ratio to 46% compared with an MR ratio of 3% in conventional nano-contact structures. It also displays highly stable oscillation (Q=350) with high emission power over 2 µW. This is significant in the development of new spintronic devices such as nanosized microwave generators and highly sensitive nanoscale magnetic field sensors.

Journal ArticleDOI
TL;DR: In this paper, the bulk minority-carrier lifetime of BaSi2 epitaxial films was determined by utilizing a drastic enhancement of lifetime by post-growth annealing at 800 °C, attributed to strain relaxation.
Abstract: We have successfully determined the bulk minority-carrier lifetime in BaSi2 epitaxial films by utilizing a drastic enhancement of lifetime by post-growth annealing at 800 °C, which is attributed to strain relaxation From the film-thickness dependence of lifetime, we reveal that the bulk lifetime is 14 µs, which is long enough for thin-film solar cell applications In addition, the sum of surface and interface recombination velocities is found to be as low as 83 cm/s presumably due to the ionic nature of BaSi2 This confirms that BaSi2 is promising as an absorption-layer material for earth-abundant thin-film solar cells

Journal ArticleDOI
TL;DR: In this paper, the authors systematically investigated the electronic structure of full-Heusler alloys with valence electron counts per formula unit of 24 by using first-principles calculation.
Abstract: We systematically investigated the electronic structure of full-Heusler alloys with valence electron counts per formula unit of 24 by using first-principles calculation. We found various semiconducting full-Heusler alloys with flat bands at the bottom of the conduction band. In terms of low toxicity and low cost, we focused on semiconducting Fe2TiSn and Fe2TiSi. We found that they could possess high thermoelectric power ranging from -300 to -160 µV/K with the electron-carrier concentrations from 1×1020 to 1×1021 cm-3 around room temperature. Our results also suggest that Fe2TiSn1-xSix alloy has a great potential to realize a higher figure-of-merit (Z T) value, compared to conventional full-Heusler alloys.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the charge dynamics and electronic structures of chemical-vapor-deposited monolayer MoS2 films and found that the ground-state exciton binding energy was about 0.48 eV.
Abstract: THz absorption and spectroscopic ellipsometry were used to investigate the charge dynamics and electronic structures of chemical-vapor-deposited monolayer MoS2 films. THz conductivity displays a coherent response of itinerant charge carriers at zero frequency. Drude plasma frequency (~7 THz) decreases with decreasing temperature while carrier relaxation time (~26 fs) is almost temperature independent. The absorption spectrum of monolayer MoS2 shows a direct 1.95 eV band gap and charge transfer excitations that are ~0.2 eV higher than those of the bulk counterpart. The ground-state exciton binding energy is found to be about 0.48 eV.

Journal ArticleDOI
TL;DR: In this article, the optical spectral properties for green semipolar (20) and (201) light-emitting diode (LED) with same indium compositions were studied, and the performance of small-area (?0.144 mm2) and large-scale (10,000 A/cm2) LEDs were compared.
Abstract: We study the optical spectral properties for green semipolar (20) and (201) light-emitting diode (LED) with same indium compositions. Compared to (201) devices, the fabricated (20) micro-LED (?0.005 mm2) showed negligible blue shift and smaller full width at half maximum (FWHM) up to extremely high current densities (10,000 A/cm2). Theoretical simulation indicates that the (20) InGaN quantum well (QW) has reduced polarization-related effects due to combined effects of electric field cancelling and Coulomb screening effect. In addition, the packaged device performance for small-area (?0.144 mm2) semipolar green (20) and (201) LEDs were also discussed. The green (20) LED showed smaller wavelength shift and narrower FWHM than green LEDs fabricated on other planes.

Journal ArticleDOI
TL;DR: In this article, a three-antenna spin-wave logic operation in a ferromagnetic thin film was investigated by using a three antenna device, where the configuration of the RF antenna determined the phase of the input spin wave, which provided a control method of logic operation.
Abstract: Spin-wave logic operation in a ferromagnetic thin film was investigated by using a three-antenna device. Binary output 1/0 signals were realized with the constructive and destructive spin-wave interference signals. It was found that the configuration of the RF antenna determines the phase of the input spin wave, which provides a control method of logic operation in spin-wave devices.

Journal ArticleDOI
TL;DR: In this paper, a top-free-type perpendicularly magnetized magnetic tunnel junctions (p-MTJ) with a synthetic antiferromagnetic (SAF) bottom reference layer consisting of [Co/Pt] superlattice and Ru spacer layers was developed.
Abstract: We developed top-free-type perpendicularly magnetized magnetic tunnel junctions (p-MTJs) with a synthetic antiferromagnetic (SAF) bottom reference layer consisting of [Co/Pt] superlattice and Ru spacer layers. We successfully demonstrated practical properties such as a low resistance–area (RA) product (<3 Ω µm2), ultralow writing voltage (<200 mV) for spin-transfer-torque (STT) switching, and high annealing stability (up to 350 °C) in the same p-MTJ cells. Moreover, the p-MTJs showed clear bi-stable states even at zero external magnetic fields, thanks to the low stray field from the SAF structure. The results are promising for both high integration and ultralow-voltage operation of STT magnetoresistive random access memory (MRAM).

Journal ArticleDOI
TL;DR: In this paper, X-ray diffraction analysis reveals [0001]-oriented hexagonal GaN with (0002) peak rocking curve full width at the half maximum (FWHM) of 544 arcsec.
Abstract: Epitaxial GaN films were grown by metal organic chemical vapor deposition (MOCVD) on functionalized epitaxial graphene (EG) using a thin (~11 nm) conformal AlN nucleation layer. Raman measurements show a graphene 2D peak at 2719 cm-1 after GaN growth. X-ray diffraction analysis reveals [0001]-oriented hexagonal GaN with (0002) peak rocking curve full width at the half maximum (FWHM) of 544 arcsec. The FWHM values are similar to reported values for GaN grown by MOCVD on sapphire. The GaN layer has a strong room-temperature photoluminescence band edge emission. Successful demonstration of GaN growth on EG opens up the possibility of III–nitride/graphene heterostructure-based electronic devices and promises improved performance.