Improved quality GaN grown by molecular beam epitaxy using In as a surfactant

Widmann, F.; Daudin, B.; Feuillet, G.; Pelekanos, N.T.; Rouvière, Jean-Luc

doi:10.1063/1.122539

Cited by 154 publications

(97 citation statements)

References 17 publications

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“…3 Surfactants are expected to modify the kinetics of epitaxial growth, therefore choosing the adequate surfactant could result in the improvement of crystal quality by controlling the surface diffusion length of the adatoms. Recently, some experimental reports on In surfactant effects investigated from a viewpoint of optical, 4-6 electrical, 6 and growth properties 7 have been published. All those studies showed positive effects of In, supplied on the surfaces during growth, to improve the crystal quality of GaN.…”

Section: ͓S0003-6951͑99͒00345-9͔mentioning

confidence: 99%

Effect of indium doping on the transient optical properties of GaN films

Kumano

Hoshi

Tanaka

et al. 1999

Applied Physics Letters

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We have investigated the effects of In doping on the optical properties of GaN films grown by gas-source molecular-beam epitaxy. Time-resolved photoluminescence was carried out to study the transient optical properties of the epitaxial films. In comparison to the undoped GaN film, the spontaneous emission lifetime was prolonged from below 20 to 70 ps by doping with In. Under high-excitation density, stimulated emission was observed from both samples. The threshold excitation density was found to be reduced in the In-doped sample. These significant improvements of the optical properties are attributed to the effective suppression of the formation of the nonradiative recombination centers caused by a change of the growth kinetics induced by a small amount of In supplied during growth of the GaN films. © 1999 American Institute of Physics. ͓S0003-6951͑99͒00345-9͔GaN and related III-V nitride materials have recently drawn a great deal of attention mainly because of their possible applications in light emitting devices operating in the green, blue, and ultraviolet wavelength regions. InGaN ternary alloys are widely used as the active layer for practical devices such as blue/green light-emitting diodes 1 and violet laser diodes. 2 A further extension to shorter wavelength requires the GaN or AlGaN as active layers. However, devices realized with these active layers are rare, partly because materials with wide band gaps energy easily suffer from the formation of nonradiative recombination centers which may lead to a deterioration in luminescence efficiency. A solution to this problem may be to use a surfactant. 3 Surfactants are expected to modify the kinetics of epitaxial growth, therefore choosing the adequate surfactant could result in the improvement of crystal quality by controlling the surface diffusion length of the adatoms. Recently, some experimental reports on In surfactant effects investigated from a viewpoint of optical, 4-6 electrical, 6 and growth properties 7 have been published. All those studies showed positive effects of In, supplied on the surfaces during growth, to improve the crystal quality of GaN.In this study, we demonstrate the effect of In doping on the improvement of crystal quality by performing timeresolved photoluminescence ͑TRPL͒ spectroscopy. Because the carrier lifetime reflects the concentration of recombination centers directly, this investigation method provided us with a sensitive probe for detection of nonradiative recombination centers. The excitation density was chosen in the range where the corresponding photogenerated carrier density was around and above the Mott density. This allowed us to explore the optical properties under a high carrier density similar to what is found in commercial devices operating under high carrier injection.In-doped GaN films as well as undoped films ͑both approximately 0.4 m thick͒ were prepared by gas-source molecular-beam epitaxy ͑GS-MBE͒ on low-temperature grown GaN buffer/Al 2 O 3 substrate. Details about the growth procedure can be found in Ref....

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Section: ͓S0003-6951͑99͒00345-9͔mentioning

confidence: 99%

Effect of indium doping on the transient optical properties of GaN films

Kumano

Hoshi

Tanaka

et al. 1999

Applied Physics Letters

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confidence: 99%

“…Only under extreme Ga-rich conditions, close to the onset of Ga-droplet formation, can smooth surfaces be achieved [5,6]. Recent experimental studies indicate that the presence of an In adlayer also leads to a smooth surface morphology and a better crystal quality [7][8][9][10].In order to understand why the presence of In or excess Ga leads to smoother surfaces, it is essential to know how these atoms modify the surface reconstruction and how the modified surface affects adatom kinetics. To address these issues, we performed total-energy calculations and geometry optimizations employing density-functional theory within the local-density approximation (LDA).…”

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confidence: 99%

Adatom Kinetics On and Below the Surface: The Existence of a New Diffusion Channel

et al. 2003

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Employing density-functional theory in combination with scanning tunneling microscopy, we demonstrate that a thin metallic film on a semiconductor surface may open an efficient and hitherto not expected diffusion channel for lateral adatom transport: adatoms may prefer diffusion within this metallic layer rather than on top of the surface. Based on this concept, we interpret recent experiments: We explain why and when In acts as a surfactant on GaN surfaces, why Ga acts as an autosurfactant, and how this mechanism can be used to optimize group-III nitride growth. DOI: 10.1103/PhysRevLett.90.056101 PACS numbers: 68.35.Fx, 68.37.Ef, 81.15.Aa Most known transport mechanisms on semiconductor surfaces have rather high activation temperatures: typically a ratio between activation and melting temperature well above 0.5 is found (T act =T melt > 0:5). Growing at lower temperature typically results in a rough surface morphology. Recently, a number of interesting transport mechanisms having low activation energies have been discussed. One example is the diffusion of transition metal atoms into bulk Si, which may actually be more efficient than diffusion on the surface [1]. Surface morphology changes mediated by bulk vacancy transport [2] and vacancy mediated surface diffusion [3] have also been discussed recently for metals. In this Letter, we discuss a growth mechanism in which the surface transport involves adatom diffusion below a metallic adlayer on a semiconductor surface. Employing state-of-the art first principles calculations and scanning tunneling microscopy, we demonstrate that adatoms may prefer to incorporate and diffuse between the adlayer and the substrate. This mechanism, which we call adlayer enhanced lateral diffusion (AELD) becomes activated already at rather low temperatures, thereby enabling the growth of materials having a high melting temperature even at modest temperatures.The materials system for which this mechanism is demonstrated are the group-III nitrides (GaN, InN, AlN, and their alloys). The members of this technologically important class of materials are strongly bonded and exhibit high melting temperatures. For example [4], GaN has a melting temperature of 2791 K and so the optimum growth temperature is expected to be higher than 1400 K. However, since GaN decomposes in vacuum when the temperature exceeds 1200 K, low pressure growth methods such as molecular beam epitaxy (MBE) can be performed only at temperatures well below the decomposition temperature. One might therefore expect that MBE growth results in a poor surface morphology and indeed, this is found for a large range of possible growth conditions. Only under extreme Ga-rich conditions, close to the onset of Ga-droplet formation, can smooth surfaces be achieved [5,6]. Recent experimental studies indicate that the presence of an In adlayer also leads to a smooth surface morphology and a better crystal quality [7][8][9][10].In order to understand why the presence of In or excess Ga leads to smoother surfaces, it is essential to k...

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“…In the θ-2θ profile of LI1, the strong diffraction peak at 31.3° for the InN (0002) can be observed, implying the highquality InN growth. From the XRCs along the symmetric InN (0002) and asymmetric InN (10)(11)(12)(13)(14)(15), it was found that FWHMs of LI1 were much wider than those of HG2, indicating LI1 had lower structural quality with greater tilt and twist misorientation. In our work, InN films with LT-InN buffer were typically inferior compared with those with HT-GaN buffer.…”

Section: Inn Buffer and (Gan + Inn) Buffermentioning

confidence: 99%

“…freely on the surface, with a greater probability of exploring the possible incorporation site, 14) thus improving the structural quality of InN film. Figure 3 shows the XRD θ-2θ profiles of the samples using IT-GaN buffers (IG1, IG2 and IG3).…”

Section: Jcs-japanmentioning

confidence: 99%

Investigation on buffer layer for InN growth by molecular beam epitaxy

Yao

Sekiguchi

Ohgaki³

et al. 2010

J. Ceram. Soc. Japan

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The effects of various buffer layers on the InN growth were studied by using atomic force microscopy (AFM), X-ray diffraction (XRD), KOH wet etching and photoluminescence (PL). GaN or InN buffers with various temperatures and conditions were prepared for the InN growth by using plasma-assisted molecular beam epitaxy (PAMBE). For GaN buffers, the InN polarity was controlled by the GaN polarity. Namely, high temperature buffers (HT, 765°C-880°C) led to -c polar InN with better quality, while intermediate-temperature buffers (IT, 500°C-650°C) to + c polar InN with lower quality. When InN buffer was used, the quality of main InN was lower than that on GaN buffer. This reason is attributed to the twist misorientation (rotation of InN unit cell along c-axis) in InN/InN-buffer/sapphire structure. This drawback has been effectively suppressed by a longer substrate nitridation, or by inserting a GaN buffer between sapphire and InN buffer. By comparing the InN grown on GaN, InN or (GaN + InN) buffer, we concluded that GaN grown at about 800°C was the optimal buffer because it had atomically flat surface and led to -c polar InN with small misorientation.

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Improved quality GaN grown by molecular beam epitaxy using In as a surfactant

Cited by 154 publications

References 17 publications

Effect of indium doping on the transient optical properties of GaN films

Effect of indium doping on the transient optical properties of GaN films

Adatom Kinetics On and Below the Surface: The Existence of a New Diffusion Channel

Investigation on buffer layer for InN growth by molecular beam epitaxy

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