The GaN Growth by a Hot Filament Metalorganic Vapor Phase Deposition Technique

Boufaden, T.; Rebey, A.; Halidou, I.; Chine, Z.; Haffouz, S.; Jani, B. El

doi:10.1002/(sici)1521-396x(199911)176:1<411::aid-pssa411>3.0.co;2-9

Cited by 4 publications

(1 citation statement)

References 12 publications

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“…GaN buffer layers were deposited on (0001) sapphire substrate in a special two-flow horizontal MOVPE reactor working at atmospheric pressure [12,13]. Trimethylgallium (TMG) and ammonia (NH 3 ) were used as Ga and N sources, respectively.…”

Section: Methodsmentioning

confidence: 99%

Annealing Effect on GaN Buffer Layer Surface

Halidou¹,

Boufaden²,

Touhami³

et al. 2001

phys. stat. sol. (a)

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We investigate the effect of annealing parameters (carrier gas, duration) on GaN buffer layers grown by metalorganic vapor phase epitaxy. The samples were characterized in situ by a laser reflectometry (LR) set-up with a He-Ne laser beam and ex situ by atomic force microscopy (AFM). The reflectivity decreases when the temperature is about 1050 C. This fact depends on the hydrogen flow rate in the H 2 þ N 2 gas mixture and the thickness of the buffer layers. The correlation between this observation and the AFM images indicates that H 2 generates a mass transport on the substrate surface and a three-dimensional (3D) mode surface morphology for thick buffer layers. For thin buffer layers this phenomenon is limited and the sample surfaces have a two-dimensional aspect (2D) similar to that obtained under N 2 rich annealing ambient. Under this ambient, no surface transformation is observed for longer annealing duration, which means that all the surface transformations occur during the temperature ramp between 600 and 1050 C.

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Section: Methodsmentioning

confidence: 99%

Annealing Effect on GaN Buffer Layer Surface

Halidou¹,

Boufaden²,

Touhami³

et al. 2001

phys. stat. sol. (a)

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Analysis of GaN decomposition in an atmospheric MOVPE vertical reactor

Fathallah

Boufaden

Jani

2007

Phys. Status Solidi (c)

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The GaN decomposition versus the annealing ambient (H 2 , N 2 + H 2 ) have been investigated in atmospheric pressure metal organic vapor phase epitaxy (AP-MOVPE) vertical reactor. A comparison between the low temperature GaN (LT-GaN) decomposition in a vertical reactor and a horizontal one was discussed in order to explain the failure of high temperature GaN (HT-GaN) growth on Al 2 O 3 using 2D buffer layer under a mixture of H 2 and N 2 in our vertical reactor. Decomposition rates versus temperature and ambient gas were measured using real time laser reflectometry. The surfaces of these films were analyzed using a scanning electron microscopy (SEM). Hydrogen seems to considerably affect the LT-GaN surface morphology by a mass transport, diffusion on the substrate surface and by a decomposition process even in the presence of ammonia and nitrogen. The high decomposition rates of the LT-GaN measured in comparison to that determined for the HT-GaN one is attributed to the amorphous-like structure of the layer and the instability of Ga-N bonds. This favors the appearance of a mirror-like gallium surface in the beginning of this layer decomposition. The presence of liquid gallium catalyzes the decomposition process. HT-GaN SEM analysis revealed that the surface of the "totally" decomposed GaN surface is dominated by gallium droplets. These were removed. The region around and under these droplets is capped by a porous like GaN film. The coalesced gallium droplets may cover some areas of partially decomposed GaN and preserve them from H 2 attack and total decomposition.

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