Step bunching on the vicinal GaN(0001) surface

Murty, M. V. R. K.; Fini, P.; Stephenson, G. B.; Thompson, Carol; Munkholm, A.; Auciello, O.; Jothilingam, R.; DenBaars, Steven P.; Speck, James S.

doi:10.1103/physrevb.62.r10661

Cited by 30 publications

(8 citation statements)

References 23 publications

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“…In fact, within that geometry the diffusion coefficient along the ripple ridges is about 6% of the diffusion coefficient across the ripple ridges at T s ϭ200 K. The question concerning the possibility to describe the decay of a periodic pattern generated by growth or ion sputtering with theoretical models dealing with an ideal profile is addressed in Ref. 15. Here the equilibration of a patterned surface which consists of a distribution of wave vectors is illustrated.…”

Section: Discussionmentioning

confidence: 99%

“…11,12,14 However, the presence of a distribution of wavelengths can explain the observed shift. 15 In fact, the amplitudes of the shorter wavelengths are expected to decay away faster than those of the longer wavelengths because of the easier mass transport between adjacent ripples. This leads to a gradual increase in the characteristic length scale.…”

Section: Discussionmentioning

confidence: 99%

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Smoothing of nanoscale surface ripples studied by He atom scattering

et al. 2003

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Thermal energy He atom scattering is used to investigate the recovery of a nanometer-scale corrugation on the ͑110͒ surface of silver. Periodic and remarkably well-ordered rippled structures with ridges oriented along the ͗001͘ and ͗11 0͘ azimuthal directions are grown by ion sputtering at grazing incidence and at a crystal temperature of 210 K. Hence, morphological equilibration of the corrugated surface is investigated in real time in the temperature range between 200 and 230 K. The activation energy for the mechanism driving surface relaxation of ͗001͘, and ͗11 0͘-oriented ripples is measured to be (0.52Ϯ0.09) and (0.43Ϯ0.05) eV, respectively. The same underlying rate limiting process-i.e., adatom detachment from the open ͗001͘ step edge-is suggested. Finally, the ripple amplitude is observed to decay with time following the inverse linear behavior, independently of the ripple orientation and of the substrate temperature. This result disagrees with the predictions of the one-dimensional model by Israeli and Kandel where an exponential decay law is obtained for the case of attachment-detachment limited kinetics.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Smoothing of nanoscale surface ripples studied by He atom scattering

et al. 2003

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“…To reduce structural defects, controlling the smooth surface and interface morphology is of prime importance, and the incorporation of indium in InGaN quantum wells is strongly influenced by the local surface misorientation. It is well-known that flat GaN layers in the step-flow mode can be obtained by both metalorganic vapor phase epitaxy (MOVPE) , and Ga-rich plasma-assisted molecular beam epitaxy (PAMBE) , On the other hand, hexagonal hillocks have been observed in PAMBE − and ammonia MBE , under N-rich conditions. It has also been reported that the surface morphology, such as step-flow and the step-bunching of AlN, can be controlled by growth parameters such as the substrate off-angle and the V/III ratio. , These experimental findings thus imply that the morphology is caused by kinetic effects rather than the static stability on the surface.…”

Section: Introductionmentioning

confidence: 99%

Effect of Step Edges on Adsorption Behavior for GaN(0001) Surfaces during Metalorganic Vapor Phase Epitaxy: An Ab Initio Study

Ohka

Akiyama

Pradipto

et al. 2020

Crystal Growth & Design

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The adsorption behavior of adatoms on stepped GaN(0001) surfaces during metalorganic vapor phase epitaxy (MOVPE) is theoretically investigated on the basis of ab initio calculations. The calculations using vicinal surfaces consisting of single layer step edges along the [11̅ 00] direction reveal that the structure of step edges depends on the growth condition. The vicinal surface with H-terminated N atoms (N ad -H+Ga-H) and that with both H-terminated N atoms and NH 2 (N ad -H+Ga-NH 2 ) are found to be stabilized under the MOVPE growth condition. Furthermore, different adsorption sites and energies of Ga and N adatoms are obtained depending on the atomic configurations of step edges and terraces. The most stable adsorption site of the Ga adatom is located at the step edge irrespective of the reconstructions, but the adsorption energy for the surface with N ad -H+Ga-NH 2 (−3.54 eV) is much lower than that with N ad -H+Ga-H (−2.68 eV). One of the striking results of the adsorption behavior of the Ga adatom is the presence or absence of the Ehrlich−Schwoebel barrier, depending on the structure of step edges. On the basis of the calculated adsorption energies and energy barriers, the adsorption behavior at the step edges on GaN(0001) surfaces depending on the growth condition of MOVPE is successfully explained.

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“…The multiple-layer step structure shown in Figs. 1͑b͒-1͑d͒ differs from the more commonly observed GaN twilled structure caused by the direction-dependent pairing of adjacent monolayer-height steps 14 and the multiple-layer steps that occur near threading dislocations. 15 A three period 20% indium concentration InGaN/GaN MQW structure is shown in Fig.…”

Section: Indium Induced Step Transformation During Ingan Growth On Ganmentioning

confidence: 80%