Surface diffusion length of Ga adatoms on (1̄1̄1̄)B surfaces during molecular beam epitaxy

Abstract

The spatial variation of the growth rate on mesa-etched GaAs (1̄1̄1̄)B substrates during molecular beam epitaxy of GaAs is measured from the period of the reflection high-energy electron diffraction (RHEED) intensity oscillation using in situ scanning microprobe RHEED. The surface diffusion length of Ga adatoms on the (1̄1̄1̄)B surface is determined from the spatial variation of the growth rate. The surface diffusion length on the (1̄1̄1̄)B surface increases as the substrate temperature is raised or the arsenic pressure is decreased. The typical value of the diffusion length is about 10 μm at a substrate temperature of 580 °C and an arsenic pressure of 5.7×10−4 Pa, which is an order of magnitude larger than that on the (100) surface along the [011] direction. The activation energy of the surface diffusion length changes with the surface reconstruction. Anisotropic diffusion, as reported for the (100) surface, is not observed on the (1̄1̄1̄)B surface.

Orientation-dependent Ga surface diffusion in molecular beam epitaxy of GaAs on GaAs patterned substrates

“…The interchange of the roles of substrate plane and sidewall between the ͑111͒A and ͑001͒ surfaces, however, might lead to different results since the effective beam fluxes are different between the substrate plane and sidewall ͑as can be understood from the difference in P Ga s and P Ga f in Table I͒, and Ga is affected by such a growth ambience. [1][2][3][4][5][6][7][8]10 The significance of the present results is that we have clearly confirmed for the first time that the experimental evidence obtained on ͑001͒ patterned substrates that Ga (111)A is longer than Ga (001) essentially originates from the crystalline anisotropy and applies to all ͑111͒A-͑001͒ systems.…”

Growth mechanisms of GaAs nanowires by gas source molecular beam epitaxy

“…3. These fits used the adatom diffusion lengths shown in Table 1, which are consistent with typical adatom diffusion lengths measured elsewhere [24,25]. In addition, to successfully fit the model to the data, it was necessary to assume that growth by bulk Fig.…”

Au impact on GaAs epitaxial growth on GaAs (111)B substrates in molecular beam epitaxy

“…32 In our case, the annealing temperature was 550 C, so that strong Ga atoms surface diffusion is expected. Meanwhile, it has been reported that (1) Au may attract a large amount of Ga even at 250 C, 33 and (2) the maximum diffusion length of Ga atoms on GaAs {111} B surface has been estimated at 5 lm at 500 C, 34 so that a significant amount of Ga atoms can be attracted towards to the Au nanoparticles at the annealing temperature of 550 C. It should be noted that, in our study, the Au was deposited on the GaAs buffer layer within the MBE system, the surface of GaAs buffer layer must be clear from possible oxidation, which makes the surface diffusion of Ga atoms much easier. To address the …”