Species intermixing and phase transitions on the reconstructed (001) surfaces of GaAs and InAs

Abstract

Scanning tunneling microscopy has been used to study the transition in surface structure between the As-terminated 2ϫ4 and c͑4ϫ4͒ reconstructions on both GaAs͑001͒ and InAs͑001͒, as a function of surface temperature under an As 2 flux. For both materials, two-phase surface reconstructions exist through the transition regime. On GaAs, the two-phase surface consists of disordered ͑2ϫ4͒-like structures plus a c͑4ϫ4͒-like phase terminating one monolayer below the 2ϫ4 surface. On InAs, a disordered asymmetric 1ϫ3 phase occurs ͕a͑1ϫ3͖͒ in addition to the main phases, one monolayer below each main phase. In both cases, simple addition of As via As-on-As chemisorption cannot account for the formation of the c͑4ϫ4͒ reconstruction from the 2ϫ4 surface. The c͑4ϫ4͒ phase is inherently multilayered, which explains how the structure can form without the addition or removal of the group III component and still maintain its layering registry with the residual 2ϫ4 or a͑1ϫ3͒ phase. One result of this formation process is the necessary intermixing of group III and group V species in the second layer of the c͑4ϫ4͒ reconstruction. Direct evidence of species intermixing on the top layer of the InAs͑001͒-a͑1ϫ3͒ structure is also shown and models for all of these reconstructions are proposed.

Interaction of Mn with GaAs and InSb: incorporation, surface reconstruction and nano-cluster formation

“…Such large-scale migration at these temperatures is consistent with the behaviour of GaAs during the (2 × 4)-c(4 × 4) reconstruction transition [55,56]. It is very difficult to speculate about transient structures present during the local destabilization of the starting reconstructions and so we present the Mn-induced strain argument as a plausible mechanism which could be tested further by detailed DFT calculations.…”

“…In the absence of incident As or Sb flux in our experiments, and given strong evidence for As removal by incident Mn, the formation of new As-rich reconstructions is likely to be hindered. However, structural rearrangements may be mediated both by mobile MnAs clusters (for which diffraction evidence was found by Braun et al [22]) and by mobile Ga atoms liberated by erosion of the As-rich reconstructions [55].…”

InAs/GaAs(001) molecular beam epitaxial growth in a scanning tunnelling microscope

“…From this point on the resolution remains remarkably stable throughout the subsequent images, with a few scan lines and contrast changes due to adatom-tip interaction. The surface slowly undergoes a transformation from (2×4) to c(4×4), with c(4×4) islands forming 1 atomic layer above the (2×4) and pits forming 1 atomic layer below [15]. The resolution of the 150x150nm 2 images is high enough to identify the 2 domains and the 0.8nm spacing of the c(4×4) reconstruction is clearly visible.…”

Interface Magnetic and Electrical Properties of CoFeB /InAs Heterostructures

“…We conclude that the annealing temperature of the substrates before the deposition has significant influence on the magnetic properties of CoFeB/InAs heterostructures, not only the appearance of the UMA, but also the saturation field and coercivity. Previous works show that InAs surface is dominated by the In atoms at low annealing temperatures with surface reconstruction of (1×2) to (2×3) at 330 °C, (2×4) at 380 °C, and (4×2) at 530 °C [26]- [28]. The surface is dominated by the As atoms with no In atoms floating on top above 530 °C.…”