2D-nucleation on (111)B micro-facet studied by microprobe-RHEED in GaAs MBE for mesa-structure fabrication

2D-nucleation on GaAs (111)B micro-facet was studied by using microprobe-RH EED/ SEM MBE, The RHEED intensity oscillation on the (111)B facet was obser ved only when incident Ga flux was relatively large, and the oscillation di sappeared by reducing Ga flux. It is indicated that, 2D-nucleation on (111) B surface occurs only when incident Ga flux is large enough so that surface Ga adatoms accumulate sufficiently to start ZD-nucleation, otherwise all o f the Ga adatoms Row away by inter-surface diffusion to (001) where they ar e incorporated into the crystal. By using simple rate equations, we show th at it is possible to estimate the critical value of Ga adatom concentration for nucleation and Ga incorporation lifetime on GaAs (111)B surface. (C) 2 000 Published by Elsevier Science B.V. All rights reserved.