The investigation of GaN growth on silicon and sapphire using in-situ time-of-flight low energy ion scattering and RHEED

Taferner, W.T.; Bensaoula, A.; Kim, E.; Bousetta, A.

doi:10.1016/0022-0248(96)00020-6

Cited by 13 publications

(7 citation statements)

References 13 publications

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“…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%

“…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. 4 In some cases, a crystalline AlN layer was reportedly formed during sapphire nitridation in MBE using NH 3 , 13,14 an ECR nitrogen plasma, 15,16 and a helicon-wave nitrogen plasma. 17 Using a constricted nitrogen plasma, it was demonstrated that both AlN and AlN x O 1Ϫx compounds were formed during sapphire nitridation.…”

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: Methodsmentioning

confidence: 99%

Section: B Angle-resolved Xpsmentioning

confidence: 99%

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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“…In ours and other groups earlier reports, this technique was used successfully on Ge, sapphire, GaAs, and Si surface studies. [1][2][3] Contrary to secondary ion mass spectroscopy, TOF-MSRI does not require ultrahigh vacuum for operation, and can work with very little loss of sensitivity in a vacuum as low as 10 Ϫ2 Torr. 4 Also, the scattering geometry is such that both ion source and detector will not interfere with the growth source beams.…”

Section: Introductionmentioning

confidence: 98%

Time of flight mass spectroscopy of recoiled ions studies of surface kinetics and growth peculiarities during gas source molecular beam epitaxy of GaN

Kim

Berishev

Bensaoula

et al. 1999

Journal of Applied Physics

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High growth rate GaN thin films were successfully grown by gas source molecular beam epitaxy and studied in situ by time of flight mass spectroscopy of recoiled ions (TOF-MSRI) and reflection high energy electron diffraction (RHEED). We show that TOF-MSRI allows for in situ monitoring and control of sapphire surface chemistry and its nitridation. In the latter case, TOF-MSRI is more sensitive to the surface changes during nitridation than RHEED. Using both RHEED and TOF-MSRI, growth of low-temperature GaN buffer layers was monitored, and their recrystallization and island-like nature were demonstrated. A model describing the probable growth mechanism for gas source molecular beam epitaxy of GaN is suggested. The model explains both the chemical dissociation of ammonia at low temperature and the origin of Ga to N TOF-MSRI peak ratio changes for various Ga and ammonia fluxes. High-resolution transmission electron microscopy studies confirm that GaN films grown with a buffer layer have excellent structural quality without any evidence of interfacial defects. Those without a buffer layer are highly defective.

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“…7 As a high vacuum growth technique, it is also compatible with in situ surface characterization tools such as reflection high energy electron diffraction ͑RHEED͒ and low energy ion scattering. [8][9][10] Despite these advantages, only a few studies have explored the use of CBE for the synthesis of group III nitride materials. 11,12 Here, we present results of the CBE growth of gallium nitride films grown by CBE on Al 2 O 3 ͑0001͒ substrates, using triethyl gallium ͑TEG͒ and ammonia (NH 3 ) as precursors.…”

mentioning

confidence: 99%

Nucleation and growth of chemical beam epitaxy gallium nitride thin films

Kim

Berishev

Bensaoula

et al. 1997

Applied Physics Letters

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Gallium nitride films have been grown on (0001) sapphire substrates by chemical beam epitaxy (CBE) using triethyl gallium (TEG) and ammonia (NH3) precursors. Prior to the CBE epi-GaN layer growth, electron cyclotron resonance plasma-assisted metal-organic molecular beam epitaxy was utilized to deposit a nucleation layer at lower temperatures. The crystallinity of CBE-grown GaN films was found to be strongly growth–temperature dependent. The degree of crystallinity was correlated with the surface carbon composition as measured in situ by mass spectroscopy of recoiled ions. The optimum growth–temperature range for CBE GaN growth was found to be between 800 and 825 °C. Within this narrow window, thin films with streaky two-dimensional reflection high-energy electron diffraction patterns and good photoluminescence properties were obtained. The surface rms roughness, as measured by atomic force microscopy, was as low as 40 Å/1 μm2 for the highest quality thin films; lattice-resolved images supported the deposition of crystalline GaN revealing hexagonal structures with the spacing anticipated for GaN.

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The investigation of GaN growth on silicon and sapphire using in-situ time-of-flight low energy ion scattering and RHEED

Cited by 13 publications

References 13 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

Time of flight mass spectroscopy of recoiled ions studies of surface kinetics and growth peculiarities during gas source molecular beam epitaxy of GaN

Nucleation and growth of chemical beam epitaxy gallium nitride thin films

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