Determination of lattice polarity for growth of GaN bulk single crystals and epitaxial layers

Ponce, Fernando; Bour, D. P.; Young, W. T.; Saunders, Martin; Steeds, John W

doi:10.1063/1.118052

Cited by 233 publications

(141 citation statements)

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“…At first a GaN nucleation layer was deposited on the (0001) sapphire substrate. Afterwards a GaN layer of about 1.5 m thickness was grown at an substrate temperature of 1040 C with trimethylgallium (TMGa) and ammonia precursors at a V/III ratio of 2,000 [9].GaN grows in MOVPE on sapphire in the (0001) direction with Ga terminated basal plans (Ga-face) [10].On the base of these substrates we prepare different surface stoichiometries by a variation of the precursor amount in nitrogen carrier gas without deterioration of the surface. In case of an increased Ga supply this can be achieved through short TMGa pulses to avoid Ga droplet formation.…”

Section: Methodsmentioning

confidence: 99%

In‐situ ellipsometry: Identification of surface terminations during GaN growth

Cobet

Schmidtling

Drago

et al. 2003

phys. stat. sol. (c)

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Spectroscopic ellipsometry (SE) is used to determine GaN surface termination during growth with metal-organic vapor phase epitaxy (MOVPE) by a correlation to well known results of plasma-assisted molecular beam epitaxy (PAMBE).The results manifest that in MOVPE under typical growth conditions the surface is not terminated by a Ga-bilayer as suggested for MBE. Moreover, it turns out that ellipsometry can be used to characterize the surface reconstruction in wurtzite GaN similar as reflectance anisotropy does for cubic III -V compounds. The optical spectra for the PAMBE reveal clear differences between growth under Ga-rich and N-rich conditions, which are attributed to the presence of a Ga-bilayer and various N-rich reconstructions on the surface [1].

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Section: Methodsmentioning

confidence: 99%

In‐situ ellipsometry: Identification of surface terminations during GaN growth

Cobet

Schmidtling

Drago

et al. 2003

phys. stat. sol. (c)

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“…39 A similar growth model of nanorod morphology depending on the MBE system geometry was also proposed by Galopin et al 40 In the last 2 years, the polarity of GaN nanorods became an attractive topic. [41][42][43][44][45] To determine the polarity of the GaN nanorods, many methods were employed, for example, convergent beam electron diffraction (CBED), 46,47 electron energy loss spectra (EELS), 48 probe Cs corrected transmission electron microscopy measurement, 49 Kelvin probe force microscopy (KPFM), 50 piezoresponse force microscopy (PFM), 51 coaxial impact-collision ion scattering spectroscopy (CAICISS) analysis, 52 circular photogalvanic effect (CPGE), 53 and wet chemical etching. 54 Most of them are also suitable for polarity measurement of the nanorod structure.…”

Section: B Catalyst-free Gan Nanorod Growthmentioning

confidence: 99%

GaN based nanorods for solid state lighting

Li¹,

Waag

2012

Journal of Applied Physics

492

394

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In recent years, GaN nanorods are emerging as a very promising novel route toward devices for nano-optoelectronics and nano-photonics. In particular, core-shell light emitting devices are thought to be a breakthrough development in solid state lighting, nanorod based LEDs have many potential advantages as compared to their 2 D thin film counterparts. In this paper, we review the recent developments of GaN nanorod growth, characterization, and related device applications based on GaN nanorods. The initial work on GaN nanorod growth focused on catalyst-assisted and catalyst-free statistical growth. The growth condition and growth mechanisms were extensively investigated and discussed. Doping of GaN nanorods, especially p-doping, was found to significantly influence the morphology of GaN nanorods. The large surface of 3 D GaN nanorods induces new optical and electrical properties, which normally can be neglected in layered structures. Recently, more controlled selective area growth of GaN nanorods was realized using patterned substrates both by metalorganic chemical vapor deposition (MOCVD) and by molecular beam epitaxy (MBE). Advanced structures, for example, photonic crystals and DBRs are meanwhile integrated in GaN nanorod structures. Based on the work of growth and characterization of GaN nanorods, GaN nanoLEDs were reported by several groups with different growth and processing methods. Core/shell nanoLED structures were also demonstrated, which could be potentially useful for future high efficient LED structures. In this paper, we will discuss recent developments in GaN nanorod technology, focusing on the potential advantages, but also discussing problems and open questions, which may impose obstacles during the future development of a GaN nanorod based LED technology.

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“…It is almost a surprise, given the differences between the two surfaces, that GaN of reasonable quality could even be grown with both polarities. Recently, the polarity identification problem has attracted the attention of electron microscopists [2] [3] [4], but there have been conflicting results.…”

Section: Introductionmentioning

confidence: 99%

Growth of Ga-face and N-face GaN films using ZnO Substrates

Hellman¹,

Buchanan²,

Wiesmann³

et al. 1996

MRS Internet j. nitride semicond. res.

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We have used plasma molecular beam epitaxy on (0 0 0 1) and (0 0 0 ) ZnO substrates to induce epitaxial growth of GaN of a known polarity. The polarity of the ZnO substrates can be easily and unambiguously determined by measuring the sign of the piezoelectric coefficient. If we assume that N-face GaN grows on O face ZnO and that Ga-face GaN grows on Zn face ZnO, then we can study the growth of both Ga and N faces. The most striking difference is the doping behavior of the two faces. Growth on the Ga-face is characterized by a higher carrier concentration and a lower threshold for Ga droplet formation.

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Determination of lattice polarity for growth of GaN bulk single crystals and epitaxial layers

Cited by 233 publications

References 0 publications

In‐situ ellipsometry: Identification of surface terminations during GaN growth

In‐situ ellipsometry: Identification of surface terminations during GaN growth

GaN based nanorods for solid state lighting

Growth of Ga-face and N-face GaN films using ZnO Substrates

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