Surface dynamics during phase transitions of GaAs(100)

Arsenic-rich GaAs(0 0 1) surface structure

“…Ripalda et al demonstrated that migration enhanced epitaxy (MEE) of GaAs(0 0 1) can also be utilized to produce the two different types of c(4 Â 4) reconstruction (a and b) depending on the As/Ga ratio [95]. Another recent STM study of the initial stage of the transition from the c(4 Â 4) to the (2 Â 4) reconstruction on MBE grown GaAs(0 0 1) favors models of the c(4 Â 4) structure with species intermixing in the first and/or second layer, because the proposed mechanism of a phase-transitioninduced Ga atomic jump would be more likely with Ga located in the topmost layers than with pure As [96].…”

As-rich reconstruction stability observed by high temperature scanning tunnelling microscopy

“…These spots appear larger than mere As-As-dimers, and are likely adsorption sites for Ga-rich clusters. It is possible that the small white spots are in fact hetero-dimers [9,10] which would account for their disordered appearance, since filled-state imaging is sensitive to primarily the group V species, in this case As. Further the excess Ga could be stored in the missing dimer row trenches of the (2 Â 4) reconstruction, where it is known to cluster at low temperature [6], seen in Fig.…”

“…These clusters represent preferred storage sites for excess Ga. In a similar manner incommensurate reconstruction domains have been assumed to correspond to excess group-III storage, namely in the form of hetero-dimers on homo-c(4 Â 4) [9,10] and hetero-a(1 Â 3) during wetting layer formation [11][12][13].…”

Quantitative structure determination of GaAs(001) under typical MBE conditions using synchrotron X-ray diffraction

“…For decades, this surface was thought to consist of three As dimers in the unit cell [7,[21][22][23][24][25][26], although some reports claimed possible intermixing of Ga and As in GaAs(0 0 1)-cð4 Â 4Þ [27][28][29][30]. Recently, a new structure model has been proposed on the basis of STM and RHEED measurements [31], in which the surface dimers are Ga-As heterodimers.…”