GaN nucleation on 6H-SiC(0001)-(√3×√3)R30°:Ga and c-sapphire via ion-induced nitridation of gallium: Wetting layers

Sidorenko, Alexander; Peisert, Heiko; Neumann, H.; Chassé, Thomas

doi:10.1016/j.susc.2007.04.190

Cited by 8 publications

(4 citation statements)

References 13 publications

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“…Studies have shown, that lateral growth proceeds via a reactive spreading mechanism including an approximately 2 ML thick metallic wetting layer fed by outdiffusion of the metal from the droplets. 51 Regarding the mass transport of Ga in the present study, it can be assumed that the pronounced lateral growth observed here is based on the same mechanism. Characteristic for the discussed GaN film formation process is the presence of voids in the GaN film (see Figs.…”

Section: (Iv) Mass Transport By Low-energy Nitrogen Ion Sputtering Of...mentioning

confidence: 60%

Epitaxial GaN films by hyperthermal ion-beam nitridation of Ga droplets

Gerlach

Ivanov

Neumann

et al. 2012

Journal of Applied Physics

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Epitaxial GaN film formation on bare 6H-SiC(0001) substrates via the process of transformation of Ga droplets into a thin GaN film by applying hyperthermal nitrogen ions is investigated. Pre-deposited Ga atoms in well defined amounts form large droplets on the substrate surface which are subsequently nitridated at a substrate temperature of 630?°C by a low-energy nitrogen ion beam from a constricted glow-discharge ion source. The Ga deposition and ion-beam nitridation process steps are monitored in situ by reflection high-energy electron diffraction. Ex situ characterization by x-ray diffraction and reflectivity techniques, Rutherford backscattering spectrometry, and electron microscopy shows that the thickness of the resulting GaN films depends on the various amounts of pre-deposited gallium. The films are epitaxial to the substrate, exhibit a mosaic like, smooth surface topography and consist of coalesced large domains of low defect density. Possible transport mechanisms of reactive nitrogen species during hyperthermal nitridation are discussed and the formation of GaN films by an ion-beam assisted process is explained

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Section: (Iv) Mass Transport By Low-energy Nitrogen Ion Sputtering Of...mentioning

confidence: 60%

Epitaxial GaN films by hyperthermal ion-beam nitridation of Ga droplets

Gerlach

Ivanov

Neumann

et al. 2012

Journal of Applied Physics

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“…The GaN wetting on the surface effectively proceeded via reactive spreading of metallic gallium supplied in the form of droplets. They confirmed that an excess metallic gallium was useful for the GaN nucleation [8,9].…”

Section: Introductionmentioning

confidence: 75%

Reducing the warpage and dislocation density of GaN template grown by HVPE with gallium droplet treatment

Choi¹,

Oh²,

Kim³

et al. 2010

Phys. Status Solidi (c)

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The warpage of the GaN template grown by a HVPE with gallium droplet treatment (GDT) was 13.8 μm, which was reduced by 80.3% of the warpage for GaN template grown by conventional MOCVD and 43% of the warpage for GaN template grown by HVPE without GDT. The treatment of gallium droplets on sapphire was achieved by thermal evaporator at room temperature. The E2 high peak of GaN template with GDT showed at 566.5 cm‐1, whereas the E2 high peak of GaN template by MOCVD positioned at 569.5 cm‐1 in Raman scattering spectra. According to the frequency shifts of E2 high peak position for each template around 3 cm‐1, the release of compressive stress of GaN template grown by HVPE with GDT was shown. In study of FE‐SEM and Grow discharge spectroscopy (GDS), voids and concentration decline zones of gallium and aluminium in counter direction were formed at the interface between GaN epilayer and sapphire substrate during GaN growth by HVPE. We expected that the decrease of warpage and stress for GaN template with GDT could be caused by the formation of voids and concentration decline zones of gallium and aluminium. Etch pits density of GaN template with GDT was around 8.5x107/cm2. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…Ga 3d5/2 peak is in close proximity to In 3d5/2 peaks. 20,25 The best fitted peak components of the overall profile were separated based on reported results for Ga 3d5/2 and experimental data obtained after a comparison with data from a standard GaP sample (not shown here). The Ga 3d5/2 had two peak components at 18.7 and 19.8 eV corresponding primarily to Ga-N and the Ga-ON x or Ga-O related component.…”

Section: Resultsmentioning

confidence: 99%

“…The XPS peak assignment was based on accepted standard literature reports. [15][16][17][18][19][20][21][22][23][24][25][26] GaP was used as a standard sample to understand the GaN XPS peaks better, since in Ga based compound semiconductor samples, very often there is interference of Ga related XPS and Auger peaks with other elemental peaks over a wide binding energy (BE) range. …”

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confidence: 99%

Wet Etching and Surface Analysis of Chemically Treated InGaN Films

Karar¹,

Opila²,

Beebe

2011

J. Electrochem. Soc.

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This paper discusses the performance of different wet chemical etchants on InGaN. It is shown that certain etchants can be used to chemically etch and remove appreciable amounts of InGaN even though the etch rate is not as high as observed for other III-V materials. The performance of etchants studied here were (i) two different ratios of HF, HNO 3 , (ii) cyclic usage of NH 4 OH followed by HCl, (iii) hot H 2 SO 4 and H 3 PO 4 mixture, and (iv) conc. NH 4 OH. The etched surfaces have then been analyzed by x-ray photoelectron spectroscopy (XPS). Different etch residues were observed on the top surface. These results suggest an alternative to reactive plasma etching or photo-enhanced electrochemical etching of InGaN type materials. Based on the observed performance of the etchants studied, it was also possible to segregate the surface cleaning protocols and etchants. It is well known that in semiconductor materials and device fabrication, the important issues are materials' purity, growth, defect control, lithography, etching, contact formation, and device performance.1,2 Among these, etching is an important process in which the grown material is required to be partially removed using specific patterns for subsequent doping, metalization, device structure formation, etc. In such processes, the rate of material removal has to be fast and repeatable. There is another associated process, in which the top layer of a material is cleaned before subsequent growth by removing a few angstroms and associated top layer contaminants. In this cleaning process, it is essential that the top layers are removed with care and the least amount of material is wasted. Thus, this chemical cleaning process has to be one with a slow material removal rate and with the least amount of interfering residues.Such etching and cleaning may be done by electrochemical, wet chemical methods, reactive ion or sputter ion cleaning.3 Electrochemical processes are not always very selective while removing materials and often require very tight control over bias voltages and currents. Wet chemical etching is a method of removing the top layer of a material in a solvent leading to its dissolution in the reaction medium. Often the etchants are a combination of acids or a combination of bases. In wet chemical methods, with proper calibration, it is possible to retain better material crystalline quality of the etched material and by controlling the concentration of chemicals in the reaction, the material removal rate can also be rigorously controlled. However in all etch steps, residues from etching steps are present; these need to be understood to evaluate the likely effects on the subsequent electrical properties of the device created. Wet chemical etching is thus often the preferred etching mechanism for lithographic process. It has often been seen that the traditional wet chemical or electrochemical processes may also have their other limitations, even though they are quite cost effective. Inability to get high etching rates or reaction induced surface p...

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GaN nucleation on 6H-SiC(0001)-(√3×√3)R30°:Ga and c-sapphire via ion-induced nitridation of gallium: Wetting layers

Cited by 8 publications

References 13 publications

Epitaxial GaN films by hyperthermal ion-beam nitridation of Ga droplets

Epitaxial GaN films by hyperthermal ion-beam nitridation of Ga droplets

Reducing the warpage and dislocation density of GaN template grown by HVPE with gallium droplet treatment

Wet Etching and Surface Analysis of Chemically Treated InGaN Films

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