Novel GaAs surface phases via direct control of chemical potential

We combine droplet epitaxy with low energy electron microscopy imaging techniques to map the surface phase diagram of GaAs(001). The phase patterns produced in droplet epitaxy are interpreted using a simple model which links the spatial coordinates of phase boundaries to the free energy. It is thereby possible to gain important new information on surface phase stability, based on the observed sequential order of the phases away from the droplet edge. This can be used to augment existing T = 0 K phase diagrams generated by density functional theory calculations. We establish the existence of a (3 × 6) phase, and confirm, that the controversial (6 × 6) phase is thermodynamically stable over a narrow range of chemical potential.

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“…Consequently, the entire trail for zero As flux displays the c(8 × 2) reconstruction ( Fig. 3(a)) (see also [30]).…”

Section: B Time-dependent Droplet Epitaxy Phasementioning

confidence: 93%

“…However, µ Ga is difficult to control experimentally since it depends sensitively on temperature [28] and material deposition [29]. Recently, efforts have been made to control µ Ga by slowly varying the substrate temperature in the presence of liquid droplets [30]. This facilitated the study of the phase diagram in the Ga-rich limit.…”

Section: Introductionmentioning

confidence: 99%

Mapping the surface phase diagram of GaAs(001) using droplet epitaxy

Zheng

Hannikainen

Niu

et al. 2019

Phys. Rev. Materials

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“…The sample was then heated above 580°C where we would expect to observe the well-studied cð8 × 2Þ reconstruction, which is widely accepted to be stable under these conditions [13,[17][18][19]. Figure 1 contains snapshots taken from a LEEM movie [20] of GaAs(001) at 598°C, obtained under bright-field imaging conditions at an incident electron energy of 8.6 eV.…”

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confidence: 99%

Surface Phase Metastability during Langmuir Evaporation

et al. 2019

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We have directly imaged the spontaneous formation of metastable surface phase domains on GaAs(001) during Langmuir evaporation. Eventually, these metastable phases transform to the thermodynamically stable parent phase, producing a dynamic phase coexistence with a temperature dependent, time-averaged coverage. Monte Carlo simulations are used to identify the key kinetic processes and investigate the interplay between phase metastability and evolving surface morphology. This is used to explain the measured temperature dependence of the time-averaged coverage.

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On the sensitivity of convergent beam low energy electron diffraction patterns to small atomic displacements

Constantinou

Jesson

2019

Applied Surface Science

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Novel GaAs surface phases via direct control of chemical potential

Cited by 5 publications

References 29 publications

Mapping the surface phase diagram of GaAs(001) using droplet epitaxy

Mapping the surface phase diagram of GaAs(001) using droplet epitaxy

Surface Phase Metastability during Langmuir Evaporation

On the sensitivity of convergent beam low energy electron diffraction patterns to small atomic displacements

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