Structural investigation of sapphire surface after nitridation

Hashimoto, Tadao; Terakoshi, Yoshitami; Ishida, M.; Yuri, Masaaki; Imafuji, Osamu; Sugino, Takashi; Yoshikawa, A.; Itoh, Kunio

doi:10.1016/s0022-0248(98)00255-3

Cited by 37 publications

(28 citation statements)

References 9 publications

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“…The surface morphology of sapphire after nitridation is relatively unchanged as compared to the as-received sapphire, which is contrary to the results obtained in MOVPE 2,7,12 and MBE with a rf nitrogen plasma [19][20][21][22] and a constricted-plasma 18 source. In these studies, high densities of protrusions were observed on the surface.…”

Section: F Surface Morphologycontrasting

confidence: 84%

“…Ex situ measurements have been extensively used to study the nitridation process under different chemical processing conditions. 2,3,7,[10][11][12]15,18,23 …”

Section: Resultsmentioning

confidence: 99%

“…Several nitridation studies in MOVPE have observed the formation of an amorphous aluminum oxynitride (AlN x O 1Ϫx ) layer, 2,7 while other studies presented evidence for the formation of relaxed crystalline AlN on the sapphire surface. 8,9 Studies on sapphire nitridation in a MBE system using a rf nitrogen plasma suggested the formation of AlN and NO molecules on the sapphire, 3,23 as well as an AlN x O 1Ϫx intermediate compound.…”

Section: Introductionmentioning

confidence: 99%

“…18 The surface morphology of sapphire after nitridation was dependent on the nitrogen source and nitridation condition, i.e., the nitridation time and temperature. A high density of protrusions has been observed after long nitrida-tion (Ͻ20 min) in MOVPE 2,7,12 and MBE using both a rf nitrogen plasma [19][20][21][22] and a constricted plasma 18 sources. With the rf nitrogen plasma source, the formation of protrusions also depends on nitridation temperature.…”

Section: Introductionmentioning

confidence: 99%

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X-ray photoelectron spectroscopic study on sapphire nitridation for GaN growth by hydride vapor phase epitaxy: Nitridation mechanism

Dwikusuma

Kuech

2003

Journal of Applied Physics

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The nitridation of c-plane sapphire within the hydride vapor phase epitaxy system was systematically studied as a function of time and ammonia partial pressure using ex situ x-ray photoelectron spectroscopy, reflection high-energy electron diffraction, and atomic force microscopy. During the nitridation process, nitrogen was incorporated into the sapphire surface. There were two different nitrogen chemical bonding states, which can be attributed to N-Al bonds and nitrogen in oxygen-rich environment ͑'N-O'͒. As the nitridation continued, the N 1s intensity increased while the O 1s intensity decreased indicating the growth of a nitrogen-rich layer. The sapphire nitridation process can be modeled as a diffusion couple of AlN and Al 2 O 3 , where N 3Ϫ and O 2Ϫ interdiffuse in the rigid Al 3ϩ framework. Nitrogen diffuses into sapphire and substitutes for oxygen to bond with aluminum. The bond substitution is accompanied by structural changes where the AlN in-plane direction is rotated 30°with respect to the sapphire direction. The replaced oxygen diffuses out to the surface, combines with hydrogen and desorbs as H 2 O. The overall nitridation rate is determined by the slower of the two moving anions. From the x-ray photoelectron spectroscopy data, the chemical diffusion coefficient of nitrogen (D N ) and oxygen (D O ), were estimated. D N was found to be higher than D O , which suggested that the overall nitridation rate was controlled by the diffusion of oxygen to the surface. After nitridation, no protrusions were observed on the surface and no significant changes in the surface roughness were measured when compared to the as-received sapphire.

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Section: F Surface Morphologycontrasting

confidence: 84%

“…Ex situ measurements have been extensively used to study the nitridation process under different chemical processing conditions. 2,3,7,[10][11][12]15,18,23 …”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

X-ray photoelectron spectroscopic study on sapphire nitridation for GaN growth by hydride vapor phase epitaxy: Nitridation mechanism

Dwikusuma

Kuech

2003

Journal of Applied Physics

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“…This system includes the crystalline phase aluminum oxynitride spinel (γ -AlON), as well as amorphous phases. The reports in the literature, wherein aluminum oxynitride is characterized by XPS, usually take one of two experimental approaches in forming AlO x N y : (i) aluminum nitride is oxidized, either by heating in an oxygen-containing atmosphere [14,15,26,27] or by bombarding an AlN surface with Ar + ions in an O 2 environment [16] or (ii) nitridation of aluminum oxide by various means such as plasma-assisted nitridation, [28 -30] ion beam implantation, [6,7,16,31] metal-organic chemical vapor deposition [32] and reactive magnetron sputtering. [33] In most of these reports, the XPS characterization of the resulting AlO x N y consisted of scans of the unsputtered surface only.…”

Section: N1s Peakmentioning

confidence: 99%

XPS analysis of aluminum nitride films deposited by plasma source molecular beam epitaxy

Rosenberger

Baird

McCullen

et al. 2008

Surface & Interface Analysis

281

161

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aTen samples of crystalline aluminum nitride (AlN) film were deposited on sapphire and silicon substrates by a plasma source molecular beam method. The samples were analyzed using X-ray photoelectron spectroscopy (XPS) depth profiling and high-resolution X-ray diffraction. Oxygen levels were observed to decrease exponentially from the surface into the bulk film. Aluminum, nitrogen and oxygen peaks were fitted with subpeaks in a consistent manner and the subpeaks were assigned to chemical states. AlN subpeaks were observed at 73.5 eV for Al2p and 396.4 eV for N1s. An N1s subpeak at 395.0 eV was assigned to N-N defects. No direct N-O bonds are assigned; rather it is proposed that an N-Al-O bond sequence is the source of higher binding energy N1s subpeaks. The observations in this study support a model in which oxygen is bound only to aluminum in the form of Al-O octahedral complexes dispersed or clustered throughout the main AlN matrix or as Al-O bonds on the crystal grain boundaries. The data also suggest that the AlN lattice parameters are related to oxygen content, since the c-axis is observed to increase with increasing oxygen content.

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InN growth on sapphire using different nitridation procedures

Drago¹,

Werner²,

Pristovsek³

et al. 2006

Physica Status Solidi (a)

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We studied optimal sapphire nitridation conditions with ammonia for the metal‐organic vapor phase epitaxy of InN using in‐situ spectroscopic ellipsometry (SE). SE indicates the formation of a complete AlN‐containing layer on top of the sapphire surface during the first 45 s of nitridation. Further nitridation leads to a growth of the AlN‐like layer by nitrogen diffusion and to roughening. Successively, a set of high quality InN films were grown onto sapphire substrates after different nitridation duration. Electronic characterisation clearly indicates optimum InN quality for 45 s of sapphire nitridation, i.e. when only the sapphire surface is nitridated, as determined by in‐situ SE. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Structural investigation of sapphire surface after nitridation

Cited by 37 publications

References 9 publications

X-ray photoelectron spectroscopic study on sapphire nitridation for GaN growth by hydride vapor phase epitaxy: Nitridation mechanism

X-ray photoelectron spectroscopic study on sapphire nitridation for GaN growth by hydride vapor phase epitaxy: Nitridation mechanism

XPS analysis of aluminum nitride films deposited by plasma source molecular beam epitaxy

InN growth on sapphire using different nitridation procedures

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