Growth diagram of N-face GaN (0001¯) grown at high rate by plasma-assisted molecular beam epitaxy

Okumura, Hironori; McSkimming, Brian M.; Huault, T.; Chaix, C.; Speck, James S.

doi:10.1063/1.4861746

Cited by 25 publications

(18 citation statements)

References 32 publications

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“…16 For the PA-MBE growth of GaN, a metallic Ga adlayer is beneficial to enhance the migration length of adatoms. 12,17 Here, it enabled extremely smooth surfaces after the MBE growth, exhibiting clear atomic steps with rms roughness of ∼0.35 nm as shown in Fig. 1(b).…”

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confidence: 85%

Single-crystal N-polar GaN p-n diodes by plasma-assisted molecular beam epitaxy

Cho

Nomoto

et al. 2017

Applied Physics Letters

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N-polar GaN p-n diodes are realized on single-crystal N-polar GaN bulk wafers by plasma-assisted molecular beam epitaxy growth. The current-voltage characteristics show high-quality rectification and electroluminescence characteristics with a high on currents ~10 kA/cm 2 , low off currents <10 -5 A/cm 2 , on/off current ratio of >10 9 , and interband photon emission. The measured electroluminescence spectrum is dominated by strong near-band edge emission, while deep level luminescence is greatly suppressed. A very low dislocation density leads to a high reverse breakdown electric field of ~2.2 MV/cm without fields plates -the highest reported for N-polar epitaxial structures. The low leakage current N-polar diodes open up several potential applications in polarization-engineered photonic and electronic devices.

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confidence: 85%

Single-crystal N-polar GaN p-n diodes by plasma-assisted molecular beam epitaxy

Cho

Nomoto

et al. 2017

Applied Physics Letters

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“…Based on the growth diagrams of Refs. [43,49], the effective substrate temperature amounts to (700 ± 10) and (715 ± 10) ℃ for the Ga-polar and N-polar samples, respectively. The difference results from the slightly larger activation energy for desorption of Ga adatoms on the GaN(000 1) surface (3.1 -3.6 eV [49,50]) compared to the GaN(0001) one (2.8 -3.2 eV [50,51]).…”

Section: Experiments and Methodsmentioning

confidence: 99%

“…[43,49], the effective substrate temperature amounts to (700 ± 10) and (715 ± 10) ℃ for the Ga-polar and N-polar samples, respectively. The difference results from the slightly larger activation energy for desorption of Ga adatoms on the GaN(000 1) surface (3.1 -3.6 eV [49,50]) compared to the GaN(0001) one (2.8 -3.2 eV [50,51]). Prior to the first (Al,Ga)N barrier growth, the substrate temperature is nominally fixed and the Ga surplus relative to the N flux is reduced to 30%.…”

Section: Experiments and Methodsmentioning

confidence: 99%

“…Nominal atomic fluxes of 5.7 × 10 14 s −1 cm −2 for N and 8.5 × 10 14 s −1 cm −2 for Ga are used, corresponding to a Ga surplus of 50% relative to the N flux, which should ensure a smooth growth for both polarities [48]. The substrate temperature is constantly tuned to set the growth conditions at the boundary below which Ga droplets would start accumulating on the surface [43,49]. This is checked by monitoring the intensity change of the reflection high-energy diffraction pattern, which dims in the presence of metal droplets.…”

Section: Experiments and Methodsmentioning

confidence: 99%

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Interface recombination in Ga- and N-polar GaN/(Al,Ga)N quantum wells grown by molecular beam epitaxy

Auzelle,

Sinito,

Lähnemann

et al. 2021

Preprint

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We explore and systematically compare the morphological, structural and optical properties of GaN/(Al,Ga)N multiple quantum wells (MQWs) grown by plasma-assisted molecular beam epitaxy (PA-MBE) on freestanding GaN(0001) and GaN(000 1) substrates. Samples of different polarity are found to be on par in terms of their morphological and structural perfection and exhibit essentially identical quantum well widths and Al content. Regardless of the crystal orientation, the exciton decay in the MQWs at 10 K is dominantly radiative and the photoluminescence (PL) energy follows the quantum confined Stark effect (QCSE) for different quantum well widths. A prominent free-to-bound transition involving interface shallow donors is, however, visible for the N-polar MQWs. At room-temperature, in contrast, the exciton decay in all samples is dominated by nonradiative recombination taking place at point defects, presumably Ca or V 𝑁 located at the bottom QW interface. Remarkably, the N-polar MQWs exhibit a higher PL intensity and longer decay times than the Gapolar MQWs at room-temperature. This improved internal quantum efficiency is attributed to the beneficial orientation of the internal electric field that effectively reduces the capture rate of minority carriers by interface trap states.

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“…GaN growth using plasma-assisted MBE has a tendency to produce rough surfaces and a high defect density for low growth temperatures (<750 C) under nitrogen-rich conditions due to small adatom diffusion. 15,16 By enhancing adatom diffusion using metal modulation epitaxy (MME), Trybus et al grew GaN with high crystalline quality at a low growth temperature of 500 C under nitrogen-rich conditions, achieving a high hole concentration of 2 Â 10 19 cm À3 . 17 In contradiction to plasma-assisted MBE, GaN growth using ammonia (NH 3 ) MBE has high crystalline quality under nitrogen-rich conditions without MME.…”

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confidence: 99%

Low p-type contact resistance by field-emission tunneling in highly Mg-doped GaN

Okumura

Martin

Grandjean

2016

Applied Physics Letters

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Mg-doped GaN with a net acceptor concentration (NA-ND) in the high 1019 cm−3 range was grown using ammonia molecular-beam epitaxy. Electrical properties of NiO contact on this heavily doped p-type GaN were investigated. A potential-barrier height of 0.24 eV was extracted from the relationship between NA-ND and the specific contact resistivity (ρc). We found that there is an optimum NA-ND value of 5 × 1019 cm−3 for which ρc is as low as 2 × 10−5 Ω cm2. This low ρc is ascribed to hole tunneling through the potential barrier at the NiO/p+-GaN interface, which is well accounted for by the field-emission model.

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Growth diagram of N-face GaN (0001¯) grown at high rate by plasma-assisted molecular beam epitaxy

Cited by 25 publications

References 32 publications

Single-crystal N-polar GaN p-n diodes by plasma-assisted molecular beam epitaxy

Single-crystal N-polar GaN p-n diodes by plasma-assisted molecular beam epitaxy

Interface recombination in Ga- and N-polar GaN/(Al,Ga)N quantum wells grown by molecular beam epitaxy

Low p-type contact resistance by field-emission tunneling in highly Mg-doped GaN

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