AlN epitaxial growth on atomically flat initially nitrided α-Al2O3 wafer

Suetsugu, Takumi; Yamazaki, Tsuyoshi; Tomabechi, Shuichi; Wada, Kunihiko; Masu, Kazuya; Tsubouchi, Kazuo

doi:10.1016/s0169-4332(97)80139-0

Cited by 21 publications

(11 citation statements)

References 6 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: 83%

“…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%

“…The normalized concentration of N 1s and O 1s was calculated from the XPS peak area divided by the corresponding atomic sensitivity factor ͑ASF͒ and normalized with the Al 2p peak area. The Al 2p peak was commonly used as a reference in sapphire nitridation studies 4,[11][12][13][14][15][16][17][18][19] since the vapor pressure of aluminum containing species ͑e.g., AlO, Al 2 O, and Al͒ is negligible at 1100°C. 24 The concentration of surface aluminum atoms was assumed therefore to be approximately constant before and after nitridation.…”

Section: Methodsmentioning

confidence: 99%

“…30,31 The Al 2p peak is commonly used as reference for other elemental peaks in previous nitridation studies. 4,[11][12][13][14][15][16][17][18][19] The Al 2p peak serves as a reference since the vapor pressure of aluminum containing species, e.g., AlO, Al 2 O, and Al, is negligible at 1100°C. Thus, the concentration or total amount of surface aluminum atoms were considered constant before and after nitridation.…”

Section: B Angle-resolved Xpsmentioning

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: 83%

“…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: Methodsmentioning

confidence: 99%

Section: B Angle-resolved Xpsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 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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High-temperature transformation of vicinal (0001) Al2O3-? surfaces: an AFM study

Kurnosikov

Van

Cousty

2000

Surf. Interface Anal.

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Development of the morphology of vicinal (0001) surfaces of α‐alumina, induced by annealing in air at 1500 °C, was studied by AFM. Our investigation shows that the resulting surface morphology depends on both the duration of thermal treatment and the surface misorientation relative to crystallographic directions. The whole vicinal surface, which is initially covered by steps of 0.21 nm height, after heating can exhibit two kinds of morphologies due to step bunching or step faceting. Step bunching occurs even after a relatively short annealing time (1 h) and is found to depend on the miscut angle. Further annealing of bunched stepped surfaces leads to the disappearance of bunching, leaving sometimes a new faceted phase. In the general case of facets, the border of faceted steps follows the [10 10] crystallographic direction, and less closely the [11 20] direction, producing zigzags. The faceting process is triggered by the step height exceeding a certain value. The origin of incubation time for the faceting process is discussed. Copyright © 2000 John Wiley & Sons, Ltd.

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