Spontaneous Formation of Indium-Rich Nanostructures on InGaN(0001) Surfaces

Chen, Huajie; Feenstra, R. M.; Northrup, John E.; Zywietz, Tosja K.; Neugebauer, Jörg

doi:10.1103/physrevlett.85.1902

Cited by 97 publications

(63 citation statements)

References 11 publications

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“…Based on the present results, we postulate that BSF formation is attributed to partial indium segregation to the growth front, leading to the formation of vacancy islands in the adlayer coverage. 55 Such islands accommodate extra indium atoms at their perimeter. The introduction of I 1 BSFs upon further growth probably also reduces the surface energy.…”

Section: Discussionmentioning

confidence: 99%

Defects, strain relaxation, and compositional grading in high indium content InGaN epilayers grown by molecular beam epitaxy

Bazioti

Papadomanolaki

Kehagias

et al. 2015

Journal of Applied Physics

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Articles you may be interested inStructural anisotropic properties of a-plane GaN epilayers grown on r-plane sapphire by molecular beam epitaxy J. Appl. Phys. 115, 213506 (2014) We investigate the structural properties of a series of high alloy content InGaN epilayers grown by plasma-assisted molecular beam epitaxy, employing the deposition temperature as variable under invariant element fluxes. Using transmission electron microscopy methods, distinct strain relaxation modes were observed, depending on the indium content attained through temperature adjustment. At lower indium contents, strain relaxation by V-pit formation dominated, with concurrent formation of an indium-rich interfacial zone. With increasing indium content, this mechanism was gradually substituted by the introduction of a self-formed strained interfacial InGaN layer of lower indium content, as well as multiple intrinsic basal stacking faults and threading dislocations in the rest of the film. We show that this interfacial layer is not chemically abrupt and that major plastic strain relaxation through defect introduction commences upon reaching a critical indium concentration as a result of compositional pulling. Upon further increase of the indium content, this relaxation mode was again gradually succeeded by the increase in the density of misfit dislocations at the InGaN/GaN interface, leading eventually to the suppression of the strained InGaN layer and basal stacking faults. V C 2015 AIP Publishing LLC. [http://dx

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Section: Discussionmentioning

confidence: 99%

Defects, strain relaxation, and compositional grading in high indium content InGaN epilayers grown by molecular beam epitaxy

Bazioti

Papadomanolaki

Kehagias

et al. 2015

Journal of Applied Physics

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“…Such conditions are needed in order to obtain Incovered surfaces. A detailed description of experimental details and growth conditions can be found elsewhere [8,19,20]. STM images of the two surfaces are shown in Figs.…”

Section: P H Y S I C a L R E V I E W L E T T E R S Week Ending 7 Febrmentioning

confidence: 99%

“…In both Figs. 4(a) and 4(b) the brighter corrugation maxima arise from top layer In atoms which have In atoms positioned in an underlying layer, thereby pushing up the top In atoms by 0:05 A [19,20].…”

Section: P H Y S I C a L R E V I E W L E T T E R S Week Ending 7 Febrmentioning

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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“…This difference can make a significant change in the In composition and crystalline qualities, including point defects such as impurities. Besides actual growth temperature, the density and nature of the threading dislocations may affect the formation of localized states in InGaN QWs, 29,30 which is believed to affect the IQE. Finally, probably the most critical but not very well-known effect is the uniformity effect of FS-GaN on luminescence properties.…”

Section: Green Leds Grown On C-plane Sapphire and Free-standing Gan Smentioning

confidence: 99%

Fundamental Studies and Development of III-N Visible LEDs for High-Power Solid-State Lighting Applications

Dupuis¹

2012

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Spontaneous Formation of Indium-Rich Nanostructures on InGaN(0001) Surfaces

Cited by 97 publications

References 11 publications

Defects, strain relaxation, and compositional grading in high indium content InGaN epilayers grown by molecular beam epitaxy

Defects, strain relaxation, and compositional grading in high indium content InGaN epilayers grown by molecular beam epitaxy

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

Fundamental Studies and Development of III-N Visible LEDs for High-Power Solid-State Lighting Applications

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