Phase transition between charge-induced long-period and (2 x 4) reconstructions of GaAs(001) surface

A phase diagram of GaAs(001) with Si delta-doped in the subsurface layer ha s been constructed as a function of temperature and As pressure. The c(4x4) , low-temperature (2x4)/c(2x8), long-period and high-temperature (2 x 4/c(2 x 8) reconstructions occur in order of increasing the surface As coverage. The long-period reconstruction induced by surface charges occurs in the mi ddle of the (2 x 4)/c(2 x 8) phase region, with a narrow range of the As co verage. The formation of an ideal structure of the long-period reconstructi on at a specific As coverage is suggested by the RHEED observation. The pha se transition of the long-period reconstruction has been described in terms of the As dimer row kinks and disappearance of kink ordering which is driv en by the desorption of As. (C) 1999 Elsevier Science B.V. All rights reser ved.